Amplifier models list

This page lists all amp models (types) in the current amp modelers, with brief additional information. The information applies to the Axe-Fx II series and AX8 as well for the most part. Many of the amp models are featured in factory presets.

Yek's Guide to the Fractal Audio Amplifier Models provides in-depth information about each amp model. MDProd's Gallery provides additional visuals and info.

1959SLP JUMP (based on 100W Marshall Super Lead Plexi 1959 reissue)

Models:

1. jumpered channels
2. Normal channel
3. Treble (High) channel

Cab: Marshall 4x12 (G12M, G12H)

Volume Normal, Volume Treble, Bass, Middle, Treble, Presence

Fractal Audio:

1. (about the Plexi model in the Standard/Ultra): "One of the first mods people make to real 'Plexi' Marshalls is to "clip the bright cap". The bright cap varied over the years, supposedly depending on what was lying around in the shop. The model defaults to the bright cap in the circuit. If you turn off Bright you're effectively clipping the bright cap. The bright cap in Marshalls can be very bright and harsh. However, if you crank the Master you might find the extra brightness helps compensate for the power amp getting darker."
2. (about fizz) "It's the way a Plexi is supposed to sound. That's due to the cathode follower. That raspiness helps it cut through in a mix. I own three of them and they are that fizzy." source
3. "Don't be afraid to turn the bass all the way down or the treble all the way up. Just like with the actual amp. For example, on the normal channel of a Plexi most people turn the bass way down. Otherwise it's too flubby."
4. "The old one (Plexi 100w model) has a 2.7K cathode resistor on the first stage, the new one (1959SLP) has an 820 ohm." source
5. "I based the SLP on using it with G12H(55) speakers which have a resonance of 55 Hz. When mounted in a typical cab the resonance will be in the low 70s. There is no right or wrong. Whatever sounds best." source
6. "My settings for a "typical" Plexi tone are Bass: 2, Mid: 8, Treble 7.5. Adjust Presence to taste." source
7. "What you are hearing is output transformer high frequency resonance. Old Plexis didn't do this because they had good transformers. New transformers are crappy and resonate at the cutoff frequency because they are underdamped. This causes a raspy, fizzy texture to the distortion. The transformer resonance is adjustable but the parameter isn't exposed to the user. When you turn it up you get that same squishy rasp that you are hearing. For the Plexis I have the damping set to flat with no resonance because that's how our vintage Plexis measure. Our 50W is a little underdamped but people complain about raspy high frequencies so I erred on the safe side." source

Yek's write-up

1987X JUMP (based on 50W Marshall 1987X reissue)

Models:

1. jumpered channels
2. Normal channel
3. Treble channel

Cab: Marshall 4x12 (G12M, G12H)

Volume Normal, Volume Treble, Bass, Middle, Treble, Presence

Notes: see 1959SLP

Fractal Audio:

1. "The 1987x doesn't have the 0.68uF cap on the last triode. Gives it a smoother distortion." source

Yek's write-up

5153 100W BLUE (based on EVH 5150-III)

Models:

1. Blue channel of 100w amp
2. Green channel of 100w amp
3. Red channel of 100w amp
4. Blue channel of 50w amp

Cab: 5150 4x12 or 2x12 (G12H, G12EVH)

Gain, Low, Mid, High, Volume, Presence, Resonance (only on 50w model)

Fractal Audio:

1. "IMO, it's a very good amp. The build-quality is great and the design is very good. It is similar to the previous versions but voiced a bit different. Personally, I think all of the 5150's have more gain stages than necessary which just makes for unnecessary failure points but the "OMG, this amp has sooo many toobz it must sound awesome" marketing makes it understandable. It's incredibly heavy though." source
2. "A 5150 uses a fixed bias with no adjustment. Depending on the tubes used the bias can run from average to cold. The model uses average. Some people like a colder sound. If you prefer your amps biased cold, then reduce the bias parameter to taste." source
3. "The 50W version has a different input network than the 100W version for that channel. The 50W version has about twice the gain as a result. Otherwise things are pretty similar. You can simulate this using the Input Trim knob." source
4. "The red channels (of 50w and 100w models) are identical." source
5. "Some amps have a fixed depth circuit, e.g. 5153, Freidman BE/HBE, Dirty Shirley, TripTik, Tucana, et. al. In these cases the Depth knob will default to a value that corresponds to the fixed circuit." source

Yek's write-up

59 BASSGUY (based on '59 Fender Tweed Bassman, 5F6-A)

Model:

1. Normal channel (engage Bright switch for Bright channel)

Cab: Fender 4x10 (P10R, P10Q)

Bass, Middle, Treble, Presence, Volume Normal, Volume Bright

Fractal Audio:

1. "There is no "High" channel on a 59 Bassman. There is a Normal and Bright channel. The Bright channel model is selected by turning on the Bright switch. The models are based on the higher gain input (the "1" input). To simulate the lower gain input simply set Input Trim to 0.5." source
2. "All the Fender models except the 59 Bassman and 5F8 Tweed don't have cathode followers." source

Yek's write-up

5F1 TWEED (based on Fender Tweed Champ, 5F1)

Model:

1. single channel

Cab: Fender 1x8

Volume

Fractal Audio:

1. "This particular amp exhibits a unique breakup characteristic due to its single-ended design and simple circuit."

Yek's write-up

5F1 TWEED EC (based on Fender EC Vibro-Champ)

Model:

1. single channel

Cab: Fender 1x8

Volume, Tremolo

Fractal Audio:

1. "The circuit is slightly different than the original 5F1. It has cathode bypass caps giving it more gain." source

Yek's write-up

5F8 TWEED (based on Keith Urban's '59 high-powered Fender Tweed Twin, 5F8)

Model:

1. Normal channel (engage Bright switch for Bright channel)

Cab: Fender 2x12 (P12N, but Keith Urban's cab contains Two-Rock speakers)

Presence, Middle, Bass, Treble, Volume Bright input, Volume Normal input

Fractal Audio:

1. "Based on a 1959 Fender Twin Amp. This particular model is based on Keith Urban’s “#1”. Thank you Keith for allowing us the use of your prized amplifier."
2. "All the Fender models except the 59 Bassman and 5F8 Tweed don't have cathode followers." source

Yek's write-up

65 BASSGUY BASS (based on Dweezil Zappa's '65 blackface Fender Bassman, AB165)

Models:

1. Bass channel
2. Normal channel

Cab: Fender 2x12 (Oxford)

Volume Bass, Volume Normal, Bass, Treble, fixed Presence circuit (Presence should be at 10), Bright switch (Normal channel only)

Fractal Audio:

1. "Has a pissed-off Marshall vibe to it." source
2. "The 65 Bassguy was matched to a 65 Bassman that Dweezil sent me. It's a vicious amp that sounds more like a Plexi than a Fender. It's the infamous AB165 circuit which is very crunchy and bright and does not sound like your typical Fender." source
3. "It's a crazy sounding amp, sounds nothing like your typical Fender. It was modded by Roy Blankenship." source
4. "The AB165 uses 7025 preamp tubes (which are relabeled 12AX7). The phase inverter, however, is a 12AT7. The secret to the AB165 is the summing stage. It uses a inverting summing amp to sum the Normal and Bass inputs. This stage clips, because of all the local negative feedback, quite hard." source
5. "It's Dweezil's Blankenship modified Bassman. Dweezil's Bassman has two channels like a regular Bassman. The Normal channel is "normal" and corresponds to the 65 Bassguy Nrml model. The Bass Instrument channel is modified and that's the basis for the new model (Dweezil's B-man). It has a boatload of gain and sounds more like a Plexi than a Fender." source

Yek's write-up

6G12 CONCERT (based on '60 brownface Fender Concert, 6G12)

Model:

1. Vibrato channel

Cab: Fender 4x10 (P10R, P10Q, C10R, Oxford)

Volume, Bass, Treble, Presence, Vibrato

Fractal Audio:

1. "Super 6G4 is a Brownface Fender Super. Concert 6G12 is a Brownface Fender Concert. They are very similar amps and both sound "old". They definitely have that early 60's vibe to them." source

Yek's write-up

6G4 SUPER (based on '60 brownface Fender Super, 6G4)

Model:

1. Vibrato channel

Cab: Fender 2x10 (Jensen P10R, P10Q, Oxford 10K5), Fender 2x12

Volume, Bass, Treble, Presence, Vibrato

Fractal Audio:

1. "Super 6G4 is a Brownface Fender Super. Concert 6G12 is a Brownface Fender Concert. They are very similar amps and both sound "old". They definitely have that early 60's vibe to them." source

Yek's write-up

AC-20 12AX7 BASS (based on Morgan AC20 Deluxe)

Models:

1. EF86 Bass
2. EF86 Treble
3. 12AX7 Bass
4. 12AX7 Treble

Cab: Morgan 1x12 (Alnico Gold, G12H)

Volume, Cut, Sun/Moon switch (= Bright switch), Brilliance switch (= Bass Cut), power scaling (not modeled), EF86/12AX7 switch

Fractal Audio:

1. "The AC-20 model is based on the amp with the power scaling at maximum power which effectively disables it (and sounds best IMO)." source
2. "The AC-20 has power scaling. The Axe-Fx II does not model the power scaling circuit as there is no point in that." source
3. "As with the real amp I dial in quite a bit of Hi-Cut." source
4. "My favorite is the AC-20 Deluxe." source
5. "AC-30's have a poorly designed cathode follower. The bias point is totally wrong and crushes one side of the signal considerably. IMO either the cathode resistor should be 100K or the plate resistor of the preceding stage should be higher, 200K. The clipping is extremely asymmetric. Too much IMO. A little asymmetry is good because it warms things up. Too much causes excessive even-order harmonics which makes things fuzzy and indistinct. The clipping is so asymmetric on an AC-30 that it's almost a half-wave rectifier. You can tweak this by adjusting the Preamp Bias point and/or lowering the Cathode Follower Compression. Or you can lower the Harmonics value which reduces the asymmetric distortion. The downside of that is that it then overdrives the phase inverter causing blocking distortion from excessive bias excursion. Another thing to try is to increase the Grid Clipping value which will add a little headroom. Start with the Bias point. AC-30's are very sensitive to the tube type and part tolerances. A tiny change in the bias point can make a big difference. The default bias point is based on Mullard ECC83 tubes. I prefer the AC-20 because it doesn't have a cathode follower so doesn't suffer from these problems. The cathode follower in an AC-30 doesn't even do all that much. Normally you use a cathode follower to preset a low-impedance source to the tone stack but the tone stack in an AC-30 doesn't present that great of a load anyways." source
6. "One reason I like the AC-20 is that it runs the tubes hotter and exhibits less crossover distortion." source
7. "The Sun/Moon equals the Bright Switch. The Bass/Treble switch would be different amp models. So AC20 EF86 Bass model would be the Bass/Treble switch in the Bass position, the switch on the back in EF86 position and then the Bright switch on the model is the Sun/Moon switch on the amp." source

Yek's write-up

ANGLE SEVERE 1 (based on Engl Savage 120)

Models:

1. Lead channel, Contour Off (boosts lower midrange around 500 Hz)
2. Lead channel, Contour On (boosts from 1200 Hz and cuts lower midrange)

Cab: Engl 4x12 (V30, V60)

Gain (input sensitivity), Lead (degree of distortion), Lead Boost switch, Contour switch, Bass, Middle, Treble, Rough/Smooth switch, Master, Presence, Depth Boost switch

Fractal Audio:

1. "From noon and up it's a presence boost, from noon down it's a presence cut." source

Yek's write-up

ATOMICA HIGH (based on Cameron Atomica)

Models:

1. Low gain input
2. High gain input

Cab: cabinet with G12H speakers

Thump, Presence, Bass, Middle, Treble, Master, Gain, Edge, 3-way Gain Voice switch

Fractal Audio:

1. "The Atomica can tolerate high MV because it is a "Jose-style MV". The Jose-style MV imparts a very high source resistance to the tone stack which causes much more insertion loss and therefore lower drive level into the power amp." source
2. "Cameron amps are basically modified Marshalls. The Atomica is essentially a slightly modified JCM800 with a Jose-style zener clipper." source

Yek's write-up

BAND-COMMANDER (based on '68 silverface/blackface Fender Bandmaster, AB763)

Model:

1. Vibrato channel

Cab: Fender 2x12

Vibrato channel: Volume Bright, Volume Normal, Bright switch, Treble, Bass, Tremolo

Fractal Audio:

1. "The vibrato channel is loaded down by the vibrato circuit. The normal channel isn't. You can probably get close using the vibrato channel model by increasing the MV trim." source

Yek's write-up

BIG HAIR (custom model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "It was a total guess. I just tuned it by ear. It's just my idea of what 80's hair metal might sound like." source

Yek's write-up

BLANKENSHIP LEEDS (based on Dweezil Zappa's Blankenship Leeds 21)

Model:

1. single channel

Cab: 2x10, 1x12, 2x12 (G12M)

Volume, Tone (Axe-Fx II/AX8 model: Treble), Tremolo

Fractal Audio:

1. "Based on a Blankenship Leeds which is a boutique version of an 18W Marshall. This particular amp is known for sounding “big” despite being relatively low power."
2. "The model was matched to Dweezil's amp. He loaned it to me because it was one of his favorite amps and I can see why. It's a really cool amp." source
3. "The amp has no hi-cut circuit therefore the control won't do anything. Neither will the Depth." source
4. "18W Marshalls are kind of a bad design. The phase inverter drives the power tubes too hard whioch results in excessive bias excursion.” source

Yek's write-up

BLUDOJAI CLEAN (based on Bludotone Ojai)

Models:

1. Clean channel with PAB (Pre-Amp Bypass) off
2. Overdrive channel with PAB off
3. Overdrive channel with PAB on

Cab: Bludotone 1x12, 2x12 (G12-65, EVM)

Volume, Overdrive Level, Treble, Middle, Bass, Master, Presence. Switches: Bright, Mid, Rock/Jazz. Footswitchable Pre-Amp Bypass (PAB) which bypasses the tonestack

Forum member AustinBuddy, owner of the original amp: "The model is of a 100w 6L6 BludoDrive Ojai by Bludotone amps, using Fractal's MIMIC process. The Ojai has the same schematic as the famous "Tan" boutique amp played by Robben Ford. It pairs well with the factory Rumble 4X12 cabinet. On the Ojai there is a bright cap on the Master Volume. As you turn the MV down, it will get thinner. This makes the MV even more sensitive than usual since there’s another interaction going on. To get the most range out of this amp, experiment with Master Volume and listen how it interacts with low or high Drive settings, similar to the real amp. The breakup range/tones between is wide and dynamic and can respond to your playing dynamics, getting crunchier as you dig in and cleaner as you play lighter. The amp's Bass response should increase noticeably as you turn up the Master Volume from the default MV position. Pair it with a G12-65H speaker. Cab Pack 17 has many choices (full disclosure, I produced 5 of the 6 Cabs in that Cab Pack). The BludoMix Cab in factory firmware is a 1x12 Alnico dual port cab, and will sound good but perhaps a tad darker (great for Jazz) on clean sounds than the G12-65H will. Now, if you like, put a Zen drive in front on the BludoClean amp....or a boost...and listen to how that clean channel wakes up fast for grittier leads and touch-responsiveness. For BludoLead, take the Lead default amp values. Put the Master Volume on 5. Put drive at 4-5 and Overdrive at 4-5, and experiment with the tone stack swaps above. If you want the amp to feedback effortlessly on a note, raise the overdrive setting higher combined with the gain, provided you have sufficient volume coming out your speakers to hit your guitar pickups in a reinforcing loop, it will do it! Throw a boost or Zen drive on that, if you like..." source

Fractal Audio:

1. "The tone stack in the PAB models is a neutral tone stack which is the same as lifting the ground. Put all knobs at noon if you want authentic." source
2. "The tone stack in the PAB models is a neutral tone stack which is the same as lifting the ground. Put all knobs at noon if you want authentic. Unlike the amp, however, you can actually adjust the tone controls and something will happen. In the virtual realm we can have lifted tone stacks that actually still work." source
3. "Pre, mid and post aren't absolute locations. They're relative to the particular model. In the Lead model there is a buffer and then three gain stages IIRC. Pre means the tone stack is before the three gain stage in this case. Changing it to Mid would put it after the first gain stage. In the Clean model there is only a buffer and one gain stage. In this case mid means the stack is between the buffer and gain stage. Changing it to pre would put it before the buffer. Since there are only two tubes pre would indicate before the buffer which is not what we want. In the PAB model there is no tone stack so I put a neutral tone stack after the gain stages (with a fixed attenuation after the buffer). This allows the most flexibility. The HRM case the neutral tone stack is replaced by a Marshall tone stack." source

Yek's write-up

BOGFISH BROWN (based on Bogner Fish preamp)

Models:

1. Strato channel
2. Brown channel

Strato and Brown channels: Master, Gain, Bass, Mid, Treble

Fractal Audio:

1. "I used the power amp models from the XTC." source

Yek's write-up

BOUTIQUE 1 (based on Matchless Chieftain)

Models:

1. single channel
2. boosted for more gain and high-frequency emphasis

Cab: Matchless 2x12 (G12M and G12H)

Volume, Master, Bass, Mid, Treble, Brilliance

Yek's write-up

BRIT 800 (based on 50W Marshall JCM 800 2204)

Model:

1. single channel

Cab: Marshall 4x12 (G12M, G12H, G12-75, V30)

Pre-Amp, Bass, Middle, Treble, Presence, Master

Fractal Audio:

1. "It is a very bright model. However, it sounds exactly like the amp it was based on. If it is too bright, you can adjust the various tone controls and parameters to reduce the brightness to your tastes. They are designed to be run loud and the brightness decreases as the MV is increased. The sound of 80's hair metal for sure." source
2. "The saturation switch switches in a zener diode clipping stage right before the tone stack. This is the Arrendondo Mod." source
3. "Rips my head off here. I have to turn the presence way down. Check the MV. Too high and will get muddy." source
4. "That "interference" is due to all the treble peaking used in the design. JCM800s have quite a bit of treble boost. When you first attack the string the note is unpitched. It's basically a brief explosion of noise. The treble boosting amplifies the upper frequencies of this noise burst which is what you hear. However, when you playing in a loud mix that treble boosting helps the sound cut. Modern designs use more carefully crafted treble boosting to retain the cut but tame some of the harshness of the attack. This is accomplished typically by putting a capacitor in parallel with the plate resistor(s) which rolls off around a few kHz. This preserves the treble boost in the upper midrange but softens the attack. I believe the SLO100 was one of the first amps to do this. You can see this in the Axe-Fx II as your Triode Freq parameters. You can soften the JCM800 attack by lowering the Triode Freq values. Most modern hi-gain designs use some form of HF rolloff like this. Another reason is that JCM800s use relatively low amounts of negative feedback (which is why they're so loud). This causes a treble boost in the power amp. Increase the Damping parameter to increase the negative feedback." source
5. "Those amps are all designed to get their character from power amp distortion. If you don't push the power amp all you are hearing is the preamp which is voiced to be trebly. The power amp then compresses the highs and the sound gets fatter." source
6. "It's a vertical input Canada export version. I went through several before settling on this one as it was the best sounding by far." source
7. (about moving Master volume to the post phase inverter) "It's called PPI MV or the "Lar-Mar Mod"." source
8. "At low MV the source resistance into the PI is low which raises the highpass frequency due to the coupling cap and raises the lowpass frequency due to the Miller capacitance and snubber. As you increase the MV the source resistance increases which decreases both of these things. As you keep raising the MV the source resistance then starts to decrease as you get above 50% of the pot value." source
9. "Some of them are really dull. We have two 50 watters. One is a Canadian export with bat-handle switches and sounds glorious. All nasty and spitty and full of "artifacts". The other is a "regular" one with the rocker switches. It sounds like it has a blanket over it in comparison. Our model is based on the Canadian one. Oh, and I should add that someone removed the bright cap from the Canadian one. Probably because it's so nasty with it in. I installed a new one to bring it back to it's original glory. The key to JCM800's is to crank the MV to overcome the brightness of the preamp." source
10. "Our reference amp had the bright cap removed by a previous owner. I put it back in. I like it on, even with a bright guitar." source

Yek's write-up

BRIT 800 #34 (custom model, based on Marshall JCM 800 with Santiago #34 modifications)

Model:

1. custom Fractal Audio model

Notes: see Brit 800

Fractal Audio:

1. "Based on the “Santiago #34” modifications."
2. "The Brit 800 #34 does a better Slash than the AFS100 IMO. The AFS100 models are based on the actual amp but I think my version of #34 sounds more like AFD. I based the model on information I've collected over the years about the mods that were done." source
3. "The Brit 800 #34 has a ton of treble boost and will squeal with certain guitars and/or certain IRs and/or certain types of amplification. Nature of the beast. No other amp has anywhere near the amount of treble boost. The AFD100 amp that Marshall produced years later (that was supposed to be a #34 copy) has nowhere near the amount of treble boost and has a huge snubber cap on the PI (which rolls off the treble). My gut tells me that they did this because they feared there would be too many reports of pickup squeal (or the amps would be too unstable at high gain)." source

Yek's write-up

BRIT 800 MOD (custom model, based on modded Marshall JCM 800)

Model:

1. custom Fractal Audio model

Notes: see Brit 800

Fractal Audio:

1. "Based on popular modified Marshall JCM800. These mods make the amp “heavier” and less strident".

Yek's write-up

BRIT AFS100 1 (based on Marshall AFD100SCE)

Models:

1. Mode: #34
2. Mode: AFD

Cab: Marshall 4x12 (V30)

Gain, Bass, Middle, Treble, Presence, Master, #34/AFD switch

Fractal Audio:

1. "I have an actual Slash signature model and spent a lot of time measuring, listening and comparing." source
2. "The Brit 800 #34 does a better Slash than the AFS100 IMO. The AFS100 models are based on the actual amp but I think my version of #34 sounds more like AFD. I based the model on information I've collected over the years about the mods that were done." source
3. "The Brit 800 #34 has a ton of treble boost and will squeal with certain guitars and/or certain IRs and/or certain types of amplification. Nature of the beast. No other amp has anywhere near the amount of treble boost. The AFD100 amp that Marshall produced years later (that was supposed to be a #34 copy) has nowhere near the amount of treble boost and has a huge snubber cap on the PI (which rolls off the treble). My gut tells me that they did this because they feared there would be too many reports of pickup squeal (or the amps would be too unstable at high gain)." source

Yek's write-up

BRIT BROWN (custom "Brown Sound" model)

Model:

1. custom Fractal Audio model

Cab: Marshall 4x12 (G12M, G12H, G12-EVH, V30, JBL D120)

Cliff:

1. "The Brit Brown was built by ear." source
2. "Brit Brown is my personal take on what the ultimate "Brown" plexi should sound like. It's based on a 100W SLP with Arredondo mods and a few little voicing tweaks." source

Yek's write-up

BRIT JM45 (based on Marshall JTM 45)

Model

1. Treble (High) channel
2. jumpered channels

Cab: Marshall 4x12 (G12M, G12H)

Volume Normal, Volume High Treble, Bass, Middle, Treble, Presence

Fractal Audio:

1. "They had no Master Volumes so people rarely got the Drive past 3.00 since it would melt your face. Without the specter of having your skin flayed off as is afforded by a model of the amp, the temptation is to turn the Drive way up. When you do this the low notes get very muddy. Single notes can form an almost perfect square wave which will sound like a synthesizer." source
2. "Our reference amp has a 100 pF bright cap. Many JTM45s did not but I think they sound better with one. A JTM45 with a bright cap is similar to a Superlead. If you want the Channel 1 sound with an Axe-Fx use the Brit JM45 Jump model and turn the Treble Drive knob all the way down." source

Yek's write-up

BRIT JVM OD1 GREEN (based on Marshall JVM410H)

Model:

1. OD1 Green
2. OD1 Orange
3. OD1 Red
4. OD2 Green
5. OD2 Orange
6. OD2 Red

Cab: Marshall 4x12 (V30 and G12H)

Master, Bass, Middle, Treble, Gain, Presence, Resonance, Reverb

Fractal Audio:

1. "IMO, the reason the JVM sounds good is the plate cap on the second-to-last triode. That smooths out the tone considerably. The second-to-last triode is associated with "Triode 1 Freq" in the advanced parameters. You can adjust this to simulate adding a cap to the plate. The other thing that helps the tone is the 220K plate resistor on the last triode. This shifts the bias point down vs. a "classic" Marshall. Unfortunately the bias points aren't exposed to the user." source
2. "The JVM has a huge plate resistor on the cathode follower, the JS does not." source

Yek's write-up

BRIT PRE (based on Marshall JMP-1 preamp)

Model:

1. OD channel

Volume, Gain, Bass, Mid, Treble, Presence, Bass shift

Fractal Audio:

1. "The two channels have preset tone stacks. Then there is a digitally controlled 4-band graphic EQ which is the B/M/T and Presence. This technique gets around the problem of trying to digitally control a tone stack. The Triaxis uses LDRs in place of potentiometers. The Soldano X-99 uses motorized pots. Both techniques being expensive. So the JMP-1 uses a fixed tone stack and then a digitally controlled graphic EQ. The Axe-Fx model of the JMP-1 is "better" in the sense that the tone controls control the tone stack rather than a graphic EQ. You then have the separate graphic EQ to further tailor the sound. What I didn't do, and why people probably feel the model differs, is "normalize" the tone controls so that with B/M/T at noon the tone stacks match. On the Axe-Fx you might need to set the Bass to 3, Mid to 7, etc. to get the tone to match. I just used a standard Marshall tone stack whereas the JMP-1 uses a standard Marshall tone stack but the pots are replaced with fixed resistors but those values don't necessarily correspond to the pots at noon." source
2. "The JMP-1 tone controls have more range than the actual preamp. The preamp has about +/- 8 dB for each tone control while the model has the standard +/- 12 dB."

Yek's write-up

BRIT SILVER (based on 100W Marshall 2555 Silver Jubilee)

Model:

1. Lead channel

Cab: Marshall 4x12 (V30)

Presence, Bass, Middle, Treble, Gain, Master

Yek's write-up

BRIT SUPER (based on Marshall AFD100)

Model:

1. AFD mode

Notes: see Brit AFS100

Fractal Audio:

1. "Brit Super model is based on the Marshall AFD100." source

BUTTERY (custom model, loosely based on Budda Twinmaster)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "I did the Buttery model by ear. I listened to some clips of Buddas (Matchbox 20... excellent!) and tweaked the model until I thought it sounded like one. Screwed around a little with the tube bias points until it had the right balance of harmonics and called it a day."
2. "It's still the "ear tuned" version. I bought the amp but because it was so popular as-is I didn't dare change it." source
3. "Buttery is a virtual amp model that was created by ear. There is no physical, real amp that exists upon which it was based. It's like the FAS models. They exist solely in the virtual world. They all still benefit from the Quantum stuff though as they use the same underlying algorithms for the tube modeling. The amp model, regardless of how accurate it is (and it's probably grossly inaccurate as I never compared it to any actual amp) is very popular and that's why it was never matched to any real amp." source

Yek's write-up

CA3+ CLEAN (based on Custom Audio Amplifiers 3+ SE preamp)

Models:

1. Clean channel
2. Rhythm channel
3. Lead channel

Gain, Bass, Middle, Treble, Master, Bright switch. Active tube EQ: Treble and Bass

Fractal Audio:

1. "The CA3+SE model is basically an OD100." source
2. "An OD100 is the head version of a CAE 3+." source
3. "That's a "James" tone-stack. You can find simulations on-line but typically you would get close using shelving filters with frequencies of 100 and 1000 Hz." source

Yek's write-up

CALI LEGGY (based on Carvin Legacy VL100)

Model:

1. Lead channel

Cab: Carvin 2x12 or 4x12 (V30)

Presence, Treble (11kHz), Mid (650Hz), Bass (80Hz), Drive, Volume

Fractal Audio:

1. "The thing that makes a Legacy unique is the tone stack. It uses a "James" tone stack which is more like hi-fi tone controls." source

Yek's write-up

CAMERON CCV 1A (based on Cameron CCV-100)

Models:

1. (1A) channel 1, less gain
2. (1B) channel 1, more gain
3. (2A) channel 2, Bright1 switch left, Bright2 switch left, Gain Style switch left
4. (2B) channel 2, Bright1 switch left, Bright2 switch right, Gain Style switch left
5. (2C) channel 2, Bright1 switch left, Bright2 switch left, Gain Style switch right
6. (2D) channel 2, Bright1 switch left, Bright2 switch right, Gain Style switch right (source)

Channel 1: Punch (= Resonance / Depth), Presence, Master, Bass, Middle, Treble and Gain, 3-way Voicing switch (resonance), 3-way Dark switch (presence), 3-way Gain Style switch (“Jose Master” gain/clipping), 3-way Bright switch (less noticeable at higher gain settings)

Channel 2: Solo Master, Master, Bass, Middle, Treble, two Gain controls, 3-way Gain Style switch, two Bright switches, Drive switch

Fractal Audio:

1. "The amp was modeled with the Voicing switch in the middle position. The "Dark" switch is the Negative feedback control. Set Negative Feedback to 3.6 to reproduce the switch in the middle position. Set it to 9.8 to reproduce the switch in the right position. 5.0 for left position (default). The amp has a dozen switches and, frankly, there isn't a lot of difference between some of the settings. The Drive switch sounds virtually identical whether left or right. I don't like it in the middle." source
2. (about the Drive knob) "Our reference amp has a linear taper pot so the behavior is very abrupt. The model matches the amp extremely accurately (as do all G3 models)." source
3. "It's a bit of a quirky amp and kind of a one-trick pony but, man, what a trick." source
4. "Yes, it's actually not a very high gain amp. The topology is very similar to a JCM800." source
5. "The key to the CCV sound is the Sat Switch." source

Yek's write-up

CAPT HOOK 1A (based on Hook Captain 34)

Models:

1. (1A) channel 1, EQ and Boost switches off
2. (1B) channel 1, EQ and Boost switches on
3. (2A) channel 2, Edge switch off
4. (2B) channel 2, Edge switch on
5. (3A) channel 3, Edge switch off
6. (3B) channel 3, Edge switch on

Cab: Hook 2x12 or 4x12 (V30, G12H, G12-65, WGS)

Channel 1: Gain (with Pull function), Level, Bass, Mid, Treble, Boost switch, EQ bypass switch, Bright switch. Shared: Presence and Balls

Channels 2 and 3: Gain, Level, Bass, Mid, Treble, Boost switch, Edge switch (changes tone stack). Shared: Presence and Balls

Fractal Audio:

1. "This amp uses a mu follower which yields a complex distortion with smooth decay. To simulate the Boost switch use the Boost switch in the amp block as it has the same amount of gain."​ source
2. "A mu follower is similar to a cascode configuration except the output is off the cathode instead of the plate. So the output impedance is lower." source
3. (to mimic Pull Gain on clean channel) "Just set the Tonestack Type to Hook Clean 2." source
4. "The Capt. Hook's "thing" is that it's basically a JCM800 with the cathode follower replaced by a mu-follower. A mu-follower doesn't compress and distort like a cathode follower does. This results in the amp sounding more open and smoother." source
5. "The Hook Clean 1 is a Fender style tonestack which has a lot more insertion loss than the others." source
6. "The Hook uses a "mu follower" instead of a cathode follower. Cathode followers have low output impedance but distort quite easily. Mu followers address some of the problems of cathode followers." source

Yek's write-up

CAR ROAMER (based on Carr Rambler)

Model:

1. single channel

Cab: Carr 1x12 (Eminence Elsinore)

Volume, Treble, Middle, Bass, Pentode/Triode, Reverb, Tremolo

Fractal Audio:

1. "It's basically a Deluxe Reverb preamp with a cathode bias 6L6 power amp and no negative feedback. Sort of a Fender-meets-Vox thing." source

Yek's write-up

CAROL-ANN OD-2 (based on Carol-Ann OD-2)

Model:

• Overdrive channel

Master, Pre Gain, Drive, Bass, Middle, Treble, Presence, Sparkle, Shift switch

Alan Phillips: "In the real world the OD2 is very very fussy on speaker choice too. The real world speakers of choice are EVM12L in a 1x12 rear ported and 2x12 with Celestion Classic Lead 80's. I found the 12L emulation did a pretty good job. Some of the others sounded so artificial with that model. Like a Rockman. Coupled with the right cab the emulated model does a good job of representing the basic tonal signature of the amp". And: "It's not a competitive model, it's a live demo of an OD2 as tweaked by me. Damn sight better than sound clips for auditioning to guys that haven't got the ability to get to a Dealer. Clearly it doesn't give you the full experience of the full amp, but is a good tonal taster. I repaired a Soldano SLO for him one day and when he came over my house to pick it up we just decided it would be a good idea to put a CA model in there. Having the actual builder involved kind of closes the loop fully. I'm happy to endorse that model because I put a lot of hours testing it and putting together a ton of technical information, fourier analysis graphs, frequency response graphs, schematics etc that would make validation of a mathematical model much easier. In reality even though the power amp and the preamp are modeled the pre-amp got the most effort. As I said in another thread, I tuned that by putting the axe in to the actual power amp of an OD2 and running that side by side with a full OD2. The final tweaks were made like that using parametric eq blocks that were hard coded in to the model. You could call that the icing on the cake and basically put the same level of tuning into the model as I do with a actual OD2. The only difference was I was using a GUI, not resistors and capacitors."

Yek's write-up

CAROL-ANN TRIPTIK CLASSIC (based on Carol-Ann Triptik)

Models:

1. Clean channel
2. Classic channel
3. Modern channel

Cab: Carol-Ann 1x12 (Scholz Classic)

Input Level, Drive on channels 2 and 3, Bass, Middle, Treble, Presence, Master, Classic/Modern voicing switching

Fractal Audio:

1. "This TripTik is badass. Dumble meets Marshall with a sprinkle of 5150 power amp." source
2. "I think what people like about this amp is the same reason people like the BE/HBE. These amps share the same aggressive low-cut on the input and then add bass back in the power amp. This gives clear bass response without getting flubby." source
3. (speaker) "It's a Scholz Classic." source
4. "Some amps have a fixed depth circuit, e.g. 5153, Freidman BE/HBE, Dirty Shirley, TripTik, Tucana, et. al. In these cases the Depth knob will default to a value that corresponds to the fixed circuit." source

Alan Phillips from Carol-Ann (about the Classic mode): "On the real amp, you would set the Input level at 2 O'clock and the Gain at 1 to 2 O'clock to get a great classic rock rhythm tone. It's not overly different in character to the modern setting, less gain and less low end essentially."

Yek's write-up

CAROL-ANN TUCANA CLEAN (based on Carol-Ann Tucana 3)

Models:

1. Clean channel
2. Lead channel

Input Level, Bass, Mid, Treble, Gain (Overdrive channels), Master (all channels), Presence

Carol-Ann:

1. "Now I can only speak for the actual amp, but my preference of speaker is a Celestion Creamback 65, though I gig these regularly with a 2x12 with Celestion T75's. Its pretty forgiving on speakers compared with some models. The foot controller and bias monitor are two of the wonderful features of the actual amp, but are both moot in the model......unless Cliff wants to model the effects of real world mains power fluctuations from place to place, but the 'green zone' of the bias monitor is 62-65% plate idle dissipation power and it measures and compensates for plate voltage and screen power , which means the real amp runs best at a slightly cooler bias. The bias monitor just allows you to set that consistently from venue to venue regardless of the main power." source
2. "It's very very difficult for anyone to get a bad tone out of the real amp. It's designed that way, the range and limits on the controls, even the biasmon system makes it difficult for even a very inexperienced player to FU. The real amp has a more British overtone to it due to the fact I am British and I designed it. The gain staging, overdrive voicing and output stage are night and day to ANYTHING Mesa, any owner of the real amp would attest to that." source
3. "The Tuc 3 is very very tolerant of most cabs and speakers, unlike say the OD2. I feel people need to approach this model very simply. Don't mess with extended parameters, basically don't try and redesign it. Use a reliable Celestion based cabinet model. I have a fantastic 4x12 with 2 old greenbacks and two old v30s that is the best cab I've played the real amp through. In actual levels of gain with the two adjustable gain controls, the amp has a maximum gain level very similar to the Triptik, the setting of these two controls with respect to each other is critical." source
4. "Real world, it has the same amount of actual gain as the Triptik. Way more than most people would need for recording or live playing. Input gain on 10 o clock, gain on 2 o clock is a 70s /80s lead tone, put the input level up to 2 o click and it's a very sustained lead tone or a very modern heavy rhythm tone." source
5. "You don't need to crank the real amp to get a ton of overdrive. I actually designed the original for myself and I play in a rock cover band. There's nowhere I would ever be able to get the amp to the point of pushing the power tubes in to overdrive. You gain stage a design based on its application. For a design that needs a lot of overdrive at a low volume, you do most of that and the harmonic makeup in the preamp. The Tucana falls in to this category. The master volumes in a 500 seat club rarely get above 10 O Clock on the real amp and at that point there's still tons of clean headroom left. Of course the power amp adds to the harmonic content, but it adds very little overdrive. Another interesting point to note is that the Tucana has a high pass filter in the power amp feedback loop, which gives you a nice tight low end because the bass is subjected to more gain. For an amp designed to be pushed hard in to power tube overdrive, this should be omitted as all bets are off in the feedback loop when you hit the rails. In other words that filter requires headroom to function properly, as does the presence control of any amp where it's a component of the feedback loop." source

Fractal Audio:

1. "One of the best amps in the world IMO. I have a Dumble and a Trainwreck and various other boutique amps and the Tucana is better than all of them." source
2. "Some amps have a fixed depth circuit, e.g. 5153, Freidman BE/HBE, Dirty Shirley, TripTik, Tucana, et. al. In these cases the Depth knob will default to a value that corresponds to the fixed circuit." source

Yek's write-up

CITRUS A30 CLEAN (based on Orange AD30HTC)

Models:

1. Clean channel
2. Dirty channel

Cab: Orange 2x12 (V30)

Gain, Master, Bass, Middle, Treble

Yek's write-up

CITRUS BASS 200 (based on Orange AD200B bass amp)

Model:

1. single channel

Cab: Orange bass cab

Volume, Gain, Bass, Middle, Treble

Yek's write-up

CITRUS RV50 (based on Orange Rockerverb 50 MK II)

Model:

1. Dirty channel

Cab: Orange 4x12 (V30)

Dirty channel: Volume, Gain, Treble, Middle, Bass, Reverb

Fractal Audio:

1. "The model is based on a MKII." source
2. "The power amp in a Rockerverb has very little negative feedback so it will boost the highs more than most power amps." source

Yek's write-up

CITRUS TERRIER (based on Orange Tiny Terror)

Model:

1. single channel

Cab: Orange 1x12 or 2x12 (G12H)

Volume, Gain, Tone (High Cut), 7w/15w switch

Fractal Audio:

1. "The actual amp has no tone stack and a single tone control. The tone control is actually a high cut control in the power amp and is therefore replicated by the Hi Cut parameter".
2. "It's inaudible when clean." source

Yek's write-up

CLASS-A 15W TB (based on Vox AC15 Top Boost)

Model:

1. Top Boost channel

Cab: Vox 1x12 (G12M, Alnico)

Volume, Cut, Bass, Treble

Yek's write-up

CLASS-A 30W (based on Vox AC30 Hand-Wired head)

Models:

1. AC-30 (non-Top Boost)
2. AC-30 Bright (non-Top Boost)
3. AC-30HW Hot mode
4. AC-30 Top Boost

Cab: Vox 2x12 (Alnico, G12M)

• AC-30 (not Top Boost): Volume, Bright switch
• AC-30 Bright: Volume, High Cut
• AC-30 Hot: Volume, High Cut, Master
• Top Boost: Volume, Bass, Treble, High Cut
• Hardwired: Hot/Cool switch

Fractal Audio:

1. "Note that the particular AC-30 used for the model has this scratchy high end. This is reflected in the high Dyn Pres value. It's a hand-wired version and that can lead to this type of sound as the parasitics cause boosting of the very high frequencies when the amp is driven hard. The obvious solution is to turn Dyn Pres down." source
2. "I intentionally limited the midrange notch since, IMO, it's a design flaw in that tone stack. But you can recover that behavior by setting the Mid control fully CCW. Modern AC30's don't have this flaw. They use a Fender-style tone stack with a fixed mid resistor." source
3. "The bright cap value is normalized to a Drive pot of 1M. An AC30 has a 500K pot so the value will read out as half the actual value. IOW, it's displaying 60 pF which is equivalent to 120 pF." source
4. "The Hot model models the AC-30HW model set to Hot. This bypasses the EQ for more gain. For authenticity, leave all tone controls at noon."
5. "AC30's have no negative feedback on the power amp. This means the output voltage follows the speaker impedance. Therefore you get a boost at the low frequency resonance of the speaker which causes the low end to get loose when you crank it." source
6. "AC-30's have a poorly designed cathode follower. The bias point is totally wrong and crushes one side of the signal considerably. IMO either the cathode resistor should be 100K or the plate resistor of the preceding stage should be higher, 200K. The clipping is extremely asymmetric. Too much IMO. A little asymmetry is good because it warms things up. Too much causes excessive even-order harmonics which makes things fuzzy and indistinct. The clipping is so asymmetric on an AC-30 that it's almost a half-wave rectifier. You can tweak this by adjusting the Preamp Bias point and/or lowering the Cathode Follower Compression. Or you can lower the Harmonics value which reduces the asymmetric distortion. The downside of that is that it then overdrives the phase inverter causing blocking distortion from excessive bias excursion. Another thing to try is to increase the Grid Clipping value which will add a little headroom. Start with the Bias point. AC-30's are very sensitive to the tube type and part tolerances. A tiny change in the bias point can make a big difference. The default bias point is based on Mullard ECC83 tubes. I prefer the AC-20 because it doesn't have a cathode follower so doesn't suffer from these problems. The cathode follower in an AC-30 doesn't even do all that much. Normally you use a cathode follower to preset a low-impedance source to the tone stack but the tone stack in an AC-30 doesn't present that great of a load anyways." source
7. "The reference AC30 is an AC30HWHD." source

Yek's write-up

COMET 60 (based on Komet 60)

Model:

1. single channel

Volume, Treble, Middle, Bass, Presence, Hi Cut (not modeled), Touch Response (Fast/Gradual)

Fractal Audio:

1. "The Komet is definitely a unique amp. Sort of like a Fender preamp into a Marshall power amp. Unique tone stack." source
2. "The model does not have the hi-cut control." source

Yek's write-up

COMET CONCOURSE (based on Komet Concorde)

Model:

1. single channel

Volume, Treble, Middle, Bass, Presence, Hi Cut (not modeled), Touch Response (Fast/Gradual)

Fractal Audio:

1. "The Komet is definitely a unique amp. Sort of like a Fender preamp into a Marshall power amp. Unique tone stack." source
2. "The model does not have the hi-cut control." source

Yek's write-up

CORNFED M50 (based on Cornford MK50 II)

This model was named "Corncob" in the Axe-Fx II

Model:

1. Overdrive channel

Cab: Cornford 4x12 (V30)

Gain, Overdrive, Bass, Middle (500Hz), Treble, Master, Presence, Resonance

Yek's write-up

DAS METALL (based on Diezel VH4)

Notes: see Dizzy

DELUXE TWEED (based on Fender Tweed Deluxe, 5E3)

Model:

1. single channel

Cab: Fender 1x12 (P12R, C12N, Alnico)

Volume, Tone (Axe-Fx/AX8 model: Treble)

Fractal Audio:

1. "Deluxe Tweed” amp model based on a Fender 5E3 Deluxe. Note that this amp only has a single tone control. This is modeled by the Treble control in the Axe-Fx II. The Bass and Mid controls are functional and recreate the amp when set to noon. Also note that this amp suffers from extreme blocking distortion at or near maximum gain. This is common in very old designs. As it is virtually unplayable like this, the model uses a somewhat reduced level of grid conduction to lower the amount of blocking distortion and make the amp more playable at high Drive settings."
2. "The G3 version of the 5E3 Deluxe Tweed model is a hoot. Totally unpredictable, nasty, gnarly and raunchy. I couldn't stop playing it yesterday. Just like the real amp you have to be careful with your volume control and how you approach the amp so that you keep it right on the edge of playability. So cool." source
3. "The Deluxe Tweed amp model is a 5E3. The 1x12 Deluxe Tweed Mix cab is the IR." source
4. "Yup, that's the key. Crank the treble almost all the way up." source
5. "The actual amp has no grid stopper resistor on the second stage and therefore has LOTS of blocking distortion." source
6. "IMO the designs are poor because... wait for it... they exhibit a papery buzz. The problem with most cathode biased Class A amps is, 1: they aren't really Class A (more like hot Class AB) and 2: They go into Class B operation when they are overdriven. The cathode capacitor charges up and the bias point shifts dramatically. This causes lots of crossover distortion (papery buzz). It's worse on lower notes because lower notes have more energy and charge the cap more. The is probably the reason Leo Fender switched to fixed bias amps with negative feedback. Fixed bias is just that, the bias point is fixed so the amp doesn't shift into Class B operation when overdriven (not as much anyways, depends on the bias circuit, grid stoppers, etc.). Negative feedback linearizes the amp and reduces the crossover distortion (at the expense of gain). That's why the buzzing went away when you increased negative feedback. Crossover distortion is a unique sound. For cleaner sounds it tends to be objectionable. For overdriven sounds some find it desirable. EVH ostensibly liked his amps biased cold to get some crossover distortion. There are even some amps that have circuits to intentionally generate crossover distortion. Some distortion pedals also do this. Lowering the Cathode Resistance reduces the crossover distortion as it keeps the amp in Class A operation longer but the tubes run hotter and don't last as long. This is not a problem with our virtual amps though. I forget the actual values but I'm pretty certain if you look at the Cathode Resistance value for those amps it's pretty high. This means the amps are biased somewhat cold to begin with and shift to very cold as soon as overdriven." source
7. (about fuzzy lows) "That's what those amps do. Always been that way. Just to be sure I just compared the Deluxe Verb model with the reference amp and it's correct. Those are old designs. Simple circuits with minimal frequency shaping. As such there's a lot of bass going into the power amp. That coupled with the resonance magnification of the speaker impedance causes frequencies around the resonance (in the 50-100 Hz region) to distort early. The low E string is 82 Hz so it's right in that zone." source

Yek's write-up

DELUXE VERB NORMAL (based on Fender blackface Deluxe Reverb, AB763)

Models:

1. Normal channel
2. Vibrato channel

Cab: Fender 1x12 or 2x10 (C12Q, EVM 12L, JBL D120, 2x10, C10N, C10Q, P10R)

Volume, Bass, Treble, Reverb, Vibrato

Fractal Audio:

1. "A DR is numbered 1-10 so 3 on a DR is around 2.2 on the Axe-Fx. The model is based on the Vibrato input #1 which has more gain than the normal input. To simulate plugging into the #2 jack (which has half the gain) set Input Trim to 0.5." source
2. "We got our reference Deluxe Reverb out of storage today, hooked it up and measured and compared. Gain measures spot-on and A/B testing sounds identical. With a Suhr Modern guitar with stock pickups both the amp and the model were starting to break up around 3 (which equals 2.2 on the Axe-Fx since the knobs start at zero not one). A Deluxe Reverb breaks up easily since it has 6V6 power tubes. The preamp is virtually identical to a Twin Reverb but 6V6s break up earlier than 6L6s. For a given voltage into the power amp a 6V6 has about 70% of the headroom compared to a 6L6." source
3. "The values for the Deluxe Reverb model are based on measurements of an actual 65 Deluxe Reverb, not some hypothetical values on some spec sheet." source
4. (about fuzzy lows) "That's what those amps do. Always been that way. Just to be sure I just compared the Deluxe Verb model with the reference amp and it's correct. Those are old designs. Simple circuits with minimal frequency shaping. As such there's a lot of bass going into the power amp. That coupled with the resonance magnification of the speaker impedance causes frequencies around the resonance (in the 50-100 Hz region) to distort early. The low E string is 82 Hz so it's right in that zone." source
5. "We have two Deluxe Reverbs, a vintage 1965 Deluxe Reverb that the model is based on and a Reissue. The vintage one sounds great, the reissue doesn't quite sound as good. It's biased too cold. The comparison was between the model and the Reissue because the vintage amp is worth a small fortune and I only use that when actually working on models. It stays in climate controlled storage otherwise." source

Yek's write-up

DIRTY SHIRLEY (based on 40W Friedman Dirty Shirley)

Models:

1. current version of the original amp
2. earlier version of the original amp with some different component values, a little more aggressive than the regular model

Cab: Friedman 4x12 (V30, G12M, G12-65, G12H)

Gain, Master, Bass, Middle, Treble, Presence

Fractal Audio:

1. "If you want more clarity in the low mids (...) reduce Negative Feedback. Friedman's designs are a bit odd in that he takes the feedback off the speaker jack rather than off a transformer tap. (...) The amp will sound tighter and clearer in the low mids." source
2. "The design is weird as the negative feedback is taken off the speaker jack. So if you use a 16-ohm speaker you get more feedback (and much more bass) than if you use an 8-ohm speaker. (...) It's too much bass for me so I turn down the Depth and reduce Negative Feedback a bit." source
3. "At first I didn't like it but for some genres it works. The old version (new model) has a 2.2 nF cap on the cathode follower while the newer version has 4.7 nF. The larger cap smooths out the distortion. The cathode bypass cap values are different as well which changes the midrange response." source
4. "Some amps have a fixed depth circuit, e.g. 5153, Freidman BE/HBE, Dirty Shirley, TripTik, Tucana, et. al. In these cases the Depth knob will default to a value that corresponds to the fixed circuit." source
5. "I always lower the negative feedback. Friedman amps are a bit strange because the negative feedback is taken off the speaker jack instead of one of the transformer taps. The matching cabs are 16 ohms but if you use an 8-ohm cab you'll get 30% less feedback." source

Yek's write-up

DIRTY SHIRLEY 2

Notes: see Dirty Shirley

Fractal Audio:

1. "Based on an earlier version of this amp with some different component values. This model is a little more aggressive than the regular model."

DIV/13 CJ (based on Divided By 13 CJ 11)

Models:

1. non-boosted (volume knob pushed in)
2. boosted (volume knob pulled out)

Cab: Divided by 13 (G12M)

Volume (pull: Boost), Treble, Bass, Master

Fractal Audio:

1. "It is a bassy amp. Works best with single coils." source
2. "You increase the LOW CUT FREQ to reduce the fuzziness on bass notes but then it won't sound like the real thing." source

Yek's write-up

DIV/13 FT37 HIGH (based on Divided By 13 FTR 37)

Models:

1. Low: channel 1 with Mid Gain Boost off
2. High: channel 1 with Mid Gain Boost on

Cab: Divided by 13 (G12H and Alnico)

Volume (pull: Boost), Treble, Bass

Yek's write-up

DIZZY V4 BLUE 2 (based on Diezel VH4)

Models:

1. Blue faceplate, channel 2 Crunch
2. Blue faceplate, channel 3 Mega
3. Blue faceplate, channel 4 Lead
4. Silver faceplate, channel 2 Crunch
5. Silver faceplate, channel 3 Mega
6. Silver faceplate, channel 4 Lead

Cab: Diezel 4x12 (V30, G12-100)

Gain, Volume, Bass, Mid, Treble, Presence (4kHz), Deep (80Hz), Bright switch (not on channels 3 and 4)

Fractal Audio:

1. (Quantum 1.00) "The Dizzy and Herbie models were completely redone as I figured out the secret to the Diezel sound." source

Yek's write-up

DIZZY V4 SILVER 2

DOUBLE VERB NORMAL (based on '66 Fender blackface Twin Reverb)

Models:

1. Normal: based on '66 blackface Fender Twin Reverb, tuned by Andy Fuchs, AB763 circuit, Normal channel
2. Vibrato: based on the Vibrato channel of the same amp
3. Silverface: based on the Vibrato channel of a 1971 100 watts “Silverface”

Cab: Fender 2x12 (Jensen C12N, JBL D120, EVM)

Volume, Bass, Middle, Treble, Bright switch, Reverb, Vibrato

Fractal Audio:

1. To make the Twin cleaner: "Reduce MV (or MV Trim). The biggest reason Silverface Twins were cleaner is because the PI had less gain. Reducing the MV or MV Trim will simulate the lower gain." source
2. (about the original Double Verb model) "The Twin Reverb that the model is based on breaks up like that. The model is MIMIC'd and is extremely accurate. It's a Blackface Twin which breaks up easy compared to later Twins. Furthermore, as with all models, it is modeled on the "Hi" input. If you don't want it to break up as easy turn Input Trim to 0.5 to simulate using the "Low" input, reduce Input Drive and MV as necessary. You may want to turn the Bright Switch off as well. People who want squeaky clean usually turn the Bright Switch off on these amps. However, you'd be surprised that a Twin isn't nearly as clean as you think. It's just so damn loud that you get the sensation that it's clean because a light touch on the strings creates a lot of volume." source
3. "The model is extremely accurate and is based on a 1966 Blackface Twin Reverb. Part of the reason the Blackface era are so sought after is because they distort. They are NOT clean amps by any stretch." source
4. "A Dual Showman with the AB763 circuit has one less gain stage than a Twin Reverb so it will have less gain. There are two gain stages. The Vibrato channel of an AB763 Twin Reverb has three gain stages. An AA769 Dual Showman Reverb on the Vibrato channel will have similar gain as it has three gain stages. The circuit number, i.e. AB763, does not mean that the circuits are identical. It refers to the circa of the design. An AB763 Dual Showman is not the same circuit as an AB763 Twin Reverb." source

Yek's write-up

DWEEZIL'S BASSGUY (based on Dweezil Zappa's modded '65 blackface Fender Bassman, AB165)

Model:

1. Bass channel, modded by Blankenship

Cab: Fender 2x12 (Oxford)

Volume, Negative Feedback, fixed Presence circuit (Presence should be at 10)

Notes: see 65 Bassguy

Fractal Audio:

1. "It's Dweezil's Blankenship modified Bassman. Dweezil's Bassman has two channels like a regular Bassman. The Normal channel is "normal" and corresponds to the 65 Bassguy Nrml model. The Bass Instrument channel is modified and that's the basis for the new model (Dweezil's B-man). It has a boatload of gain and sounds more like a Plexi than a Fender." source
2. "Just finished matching this modded 65 Bassman that Dweezil sent me. It's a crazy sounding amp, sounds nothing like your typical Fender. It was modded by Roy Blankenship." source
3. "The 65 Bassguy was matched to a 65 Bassman that Dweezil sent me. It's a vicious amp that sounds more like a Plexi than a Fender. It's the infamous AB165 circuit which is very crunchy and bright and does not sound like your typical Fender." source
4. "The actual amp has no tone stack so for maximum authenticity all tone controls would be at noon (but don't be afraid to tweak them). In the actual amp the Treble control is re-purposed as a Negative Feedback control. Experiment with different values of Negative Feedback. Lower values are looser." source

Yek's write-up

ENERGYBALL (based on Engl Powerball)

Model:

1. Lead channel

Cab: Engl 4x12 (V30, V60)

Gain, Volume, Bass, Mid-Open, Mid-Focused, Treble, Presence, Punch Depth, Bottom, Open or Focused (boosts 300-500 Hz) mode

Yek's write-up

EURO BLUE (based on Bogner Ecstasy 20th Anniversary)

Models:

1. Blue channel, structure: Vintage
2. Blue channel, structure: Modern
3. Red channel, structure: Vintage
4. Red channel, structure: Modern

Cab: Bogner 2x12 or 4x12 (V30)

Gain, Master, Bass, Middle, Treble, Presence, Bright switch, Structure switch (gain reduction), Old/New Style switch, Excursion switch, Gain switch, Plexi Mode

Fractal Audio:

1. "People think Bogners are dark but they really aren't. The reason they seem that way is the pot tapers. Most people assume knobs should be set somewhere around noon. If you do this on a Bogner it's like turning the treble way down on a Marshall. Close your eyes and adjust the tone controls with your ears. Don't be afraid to turn them way up or way down." source
2. "Human nature is to put the knobs near noon. We are reticent to deviate much from noon. Amp designers exploit this and use different tapers to change the sound of their amps WITH THE KNOBS AT NOON. A prime example are Bogner amps. Everyone says "Bogner amps are dark". No they aren't. But he uses a Log10A taper for the treble pot. It's a standard Marshall tone stack. Usually a linear taper pot is used for the treble. The treble knob at 5.0 (noon) on a Bogner is equivalent to the treble knob at 1.0 on a Marshall. People put the knob at 5.0 and go "wow, this amp is dark". No it isn't. If you turned the treble up to 8 or 9 it would sound a lot like a Plexi but humans are reticent to turn the knobs to extremes. Amp designers know this and exploit it to give their amps a "signature sound"." source
3. "Our reference amp is a 20th anniversary and N is Bright Off, B1 is 150 pF and B2 is 1000 pF for both channels. The models default to B1. Change the Bright Cap value to 1 nF to emulate B2. Or better yet use your ears to select a value that sounds best." source

Yek's write-up

EURO UBER (based on Bogner Uberschall)

Model:

1. High gain channel

Cab: Bogner 4x12 Uberkab (G12-T75 and V30)

Gain, Master, Bass, Middle, Treble, Presence, Depth

Fractal Audio:

1. "People think Bogners are dark but they really aren't. The reason they seem that way is the pot tapers. Most people assume knobs should be set somewhere around noon. If you do this on a Bogner it's like turning the treble way down on a Marshall. Close your eyes and adjust the tone controls with your ears. Don't be afraid to turn them way up or way down." source
2. "Human nature is to put the knobs near noon. We are reticent to deviate much from noon. Amp designers exploit this and use different tapers to change the sound of their amps WITH THE KNOBS AT NOON. A prime example are Bogner amps. Everyone says "Bogner amps are dark". No they aren't. But he uses a Log10A taper for the treble pot. It's a standard Marshall tone stack. Usually a linear taper pot is used for the treble. The treble knob at 5.0 (noon) on a Bogner is equivalent to the treble knob at 1.0 on a Marshall. People put the knob at 5.0 and go "wow, this amp is dark". No it isn't. If you turned the treble up to 8 or 9 it would sound a lot like a Plexi but humans are reticent to turn the knobs to extremes. Amp designers know this and exploit it to give their amps a "signature sound"." source
3. "The feedback circuit is responsible for the behavior of the Presence and Depth controls. Certain Bogners and Diezels have a unique type of feedback circuit. There are no new parameters and nothing to do except twist the Presence and Depth knobs to your desired tone. Note that an Uberschall doesn't have a Depth knob. The default Depth value when you select the Euro Uber model is equivalent to the amp's fixed depth circuit." source

Yek's write-up

FAS 6160 (custom "5150" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "Based on the PVH 6160 model but more open and less fizzy than the original amp. Also, a virtual choke has replaced the resistor found on the original’s power supply filter. This results in a bouncier feel."

Yek's write-up

FAS BASS (custom bass model)

Model:

1. custom Fractal Audio model

Yek's write-up

FAS BROOTALZ (custom model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "This amp was an accident. I was working on the Savage model and accidentally used the input stage from an SLO100. So it's the front end of an SLO100 with the back end of a Savage. It's probably an SLO100 power amp too but I'd have to check." source

Yek's write-up

FAS BROWN (custom "Brown Sound" model)

Model:

1. custom Fractal Audio model

Yek's write-up

FAS CLASS-A (custom "Class-A" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "“Blackface” preamp into a cathode-biased 6L6 power amp with no negative feedback. This was a happy accident when originally modeling the Carr Rambler in the beta version of this release."
2. "A “Blackface” preamp into a cathode-biased 6L6 power amp with no negative feedback. This was a happy accident when originally modeling the Carr Rambler in the beta version of this release. Several mistakes were made in the model prior to MIMIC’ing the amp but the model was so well liked that we decided to make it into its own custom amp model."

Yek's write-up

FAS CRUNCH (custom "Plexi" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "Our take on the ultimate British-sounding amp. More dynamic and open than a Plexi, but with more gain."
2. "My take on the ultimate Plexi." source

Yek's write-up

FAS HOT ROD (custom "modded Marshall" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "FAS Hot Rod is my version of what a modded Marshall should be. I find the BE/HBE a little too boomy and scooped. Bogners are too dark. Splawns don't have enough compression. Etc. So it's my take on a hot-rodded Marshall tone." source

Yek's write-up

FAS LEAD 1 (custom model)

Model:

1. custom Fractal Audio model

Yek's write-up

FAS LEAD 2 (custom model)

Model:

1. custom Fractal Audio model

Yek's write-up

FAS MODERN (custom "metal" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "This model is my interpretation of the ideal modern metal tone. In the digital realm we are not constrained by the limitations that face tube amp designers so we are free to implement designs that would be nearly impossible with a tube amp. The Axe-Fx II modeling includes a variety of general purpose filters that I can place anywhere in the signal path. So I put some second-order filters in there to tighten up the tone. Implementing second-order filters in a real tube amp is difficult and costly so is rarely seen." source
2. "It's loosely based on a Recto but with tighter bass." source

Yek's write-up

FAS MODERN II (custom "metal" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "This is a tighter version of the popular FAS Modern model with a 5150-style bass boost in the tone stack."

Yek's write-up

FAS MODERN III (custom "metal" model)

Model:

1. custom Fractal Audio model

Yek's write-up

FAS RHYTHM (custom "Marshall+Mesa" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "Combines the best features of the British (Marshall) and USA (Mesa) crunch models."

Yek's write-up

FAS SKULL CRUSHER (custom "high gain" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "The nastiest, most brutal amp model to ever escape from the seventh circle."

FAS WRECK (custom "Trainwreck" model)

Model:

1. custom Fractal Audio model

Fractal Audio:

1. "Based on the original WRECKER 1 model from the Axe-Fx Ultra."

Yek's write-up

FOX ODS (based on Fuchs Overdrive Supreme 50)

Model:

1. ODS: Deep switch off, PAB on (Pre Amp Bypass)
2. ODS Deep: Deep switch on, PAB off

Cab: Fuchs 2x12 (Eminence)

Gain, High (pull: mid boost), Mid (pull: gain boost), Low, Input, Brite switch, Deep switch, Rock/Jazz switch, Master, Accent (presence/edge)

Fractal Audio:

1. "Supposedly a Dumble ODS clone but our reference amp has way more gain than our Dumble." source

Yek's write-up

FRIEDMAN BE (based on Friedman BE-100)

Models:

1. BE: based on old Marsha model, BE mode
2. BE C45: based on Mark Day's BE-100, C45 switch engaged
3. BE V1: based on Mark Day's BE-100, voice: right position (less mids)
4. BE V2: based on Mark Day's BE-100, voice: left position (more mids)
5. HBE: based on old Marsha model, HBE mode
6. HBE 2018: based on 2018 BE-100, HBE mode
7. HBE 2018 C45: based on 2018 BE-100, HBE mode, C45 switch engaged
8. HBE V1: based on Mark Day's BE-100, HBE mode, voice: right position (less mids)
9. HBE V2: based on Mark Day's BE-100, HBE mode, voice: left position (more mids)

Cab: Friedman 4x12 (V30 and/or G12M)

Gain, Master, Bass, Middle, Treble, Presence. Switches: FAT (model: FAT), C45 (treble boost), SAT (model: SAT), Voice

Fractal Audio:

1. "The old model is an original, hand-built "Marsha". It's MUCH darker than Mark's newer BE/HBE. In fact it's so dark and boomy I emailed Dave to make sure the amp was built correctly. Turns out the snubber cap is the wrong value. But even with the snubber cap corrected it's still very dark and boomy which made me question as to whether there are other components that are incorrect. So we decided to redo the model based on Mark's amp which is the amp that was the demo model at Tone Merchants." source
2. "The models are based on two different amps. The V1 and V2 are based on Mark Day's BE100. The other models are based on our original "Marsha". Like most boutique amp makers Friedman's designs have evolved over time with changes to the circuit. The original Marsha we have is dark and bassy with lots of lowpass filtering. The newer amp is brighter and tighter. For now note that V1/V2 refer to the newer amp and represent the position of the Voicing switch." source
3. "The BE/HBE has a fixed depth circuit that gives a lot of bass boost. The model defaults the Depth to match this." source.
4. "If you want more clarity in the low mids from the BE/HBE reduce Negative Feedback. Friedman's designs are a bit odd in that he takes the feedback off the speaker jack rather than off a transformer tap. The mating cab for a BE/HBE is 16 ohms which means lots of feedback. But if you connect the amp to an 8 ohm load there is about 30% less feedback. The amp will sound tighter and clearer in the low mids." source
5. "The design is weird as the negative feedback is taken off the speaker jack. So if you use a 16-ohm speaker you get more feedback (and much more bass) than if you use an 8-ohm speaker. The model is based on using the matching cab. It's too much bass for me so I turn down the Depth and reduce Negative Feedback a bit." source
6. "I always lower the negative feedback. Friedman amps are a bit strange because the negative feedback is taken off the speaker jack instead of one of the transformer taps. The matching cabs are 16 ohms but if you use an 8-ohm cab you'll get 30% less feedback." source
7. "C45 is a treble boost on the input." source
8. (Axe-Fx III) "I have one of the very first BE-100s but, on a whim, decided to buy a new one because people said they sound a "little" different. Well... more than a little. They sound very different. I got in touch with Dave to see what he changed and made those two new models." source
9. Discussion about the Bass control
10. "Some amps have a fixed depth circuit, e.g. 5153, Freidman BE/HBE, Dirty Shirley, TripTik, Tucana, et. al. In these cases the Depth knob will default to a value that corresponds to the fixed circuit." source
11. "Same here but when you watch a video Dave himself turns the bass way up. Steve Stevens and Jerry Cantrell turn the bass way up too. If I did that with my guitar it would be a muddy mess. Puzzling to me because the BE has a fixed depth circuit and a significant amount of negative feedback so there is quite a bit of bass boost in the power amp as well." source

Yek's write-up

FRIEDMAN SMALL BOX (based on Friedman Smallbox)

Model:

1. Channel 2

Cab: Friedman 2x12 (G12M)

Gain, Master, Bass, Middle, Treble, Presence, Bright switch (channel 1 only)

Fractal Audio:

1. "The schematic shows a 2.2 nF coupling cap off the first stage but the actual amp has a 4.7 nF. 2.2 nF would mean less bass. I can only assume the amp was built to the latest specs. If an amp model is "G3'd" it is deadly accurate. I go through the amps and check the values of each component, measure the voltages, compare the frequency response to the model, etc., etc., etc. If the model is too bassy for you then you would find the real amp too bassy, or at least our particular reference model." source
2. "If you want more clarity in the low mids (...) reduce Negative Feedback. Friedman's designs are a bit odd in that he takes the feedback off the speaker jack rather than off a transformer tap. (...) The amp will sound tighter and clearer in the low mids." source
3. "The design is weird as the negative feedback is taken off the speaker jack. So if you use a 16-ohm speaker you get more feedback (and much more bass) than if you use an 8-ohm speaker. (...) It's too much bass for me so I turn down the Depth and reduce Negative Feedback a bit." source
4. "I always lower the negative feedback. Friedman amps are a bit strange because the negative feedback is taken off the speaker jack instead of one of the transformer taps. The matching cabs are 16 ohms but if you use an 8-ohm cab you'll get 30% less feedback." source

Yek's write-up

FRYETTE D60 LESS (based on Fryette Deliverance 60)

Model:

1. Less gain
2. More gain

Cab: Fryette 4x12 P50E (Fane F70G)

Gain 1, Gain 2, Volume, Bass, Middle, Treble, Presence, Depth, More/Less switch

Yek's write-up

GIBTONE SCOUT (based on Gibson GA17RVT Scout)

Model:

1. single channel

Cab: Gibson 1x10

Volume, Reverb, Tremolo

Yek's write-up

HERBIE CH2+ (based on Diezel Herbert)

Models:

1. Channel 2- (Plexi)
2. Channel 2+ (JC800)
3. Channel 3 (VH4)

Cab: Diezel 4x12 *(V30, G12-K100)

Gain (not on channel 1), Bass, Middle (1 kHz), Treble, Master, Presence (> 3kHz), Deep (120Hz), Mid-Cut (not modeled), Gain Boost switch (not modeled)

Fractal Audio:

1. (Quantum 1.00) "The Dizzy and Herbie models were completely redone as I figured out the secret to the Diezel sound." source
2. (to reproduce the Mid Cut function) "Use a Peak EQ filter at 400 Hz with a Q of 1.4. Decrease its Gain until the desired scoop is achieved. Play with the Q to set the width of the scoop." source

Yek's write-up

HIPOWER BRILLIANT (based on Hiwatt DR103)

Models:

1. Normal channel
2. Brilliant channel
3. jumpered channels

Cab: Hiwatt 4x12 (Fane)

Volume, Master, Bass, Middle, Treble, Presence

Fractal Audio:

1. "I have a 1974 Hiwatt DR-103. The model is based on that. It is one of the Harry Joyce, Hylight era models. Still has the original tubes. Closet find and sounds glorious." source

Yek's write-up

HOT KITTY (based on BadCat Hot Cat 30R)

Model:

1. High gain channel

Cab: BadCat 1x12 (proprietary Celestion)

Gain, Edge, Level, Bass, Mid-range switch, Treble, Brilliance, Master

Fractal Audio:

1. "Brilliance is their name for Hi-Cut. I set the Edge control to where I thought it sounded best. It essentially does the same thing as the Bright knob though less precise."
2. "The amp has a Hi Cut but it's labeled Brilliance. It's wired backwards so turning it CW gets brighter." source
3. "Those amps make a lot of IMD. The real amp does the same thing but you wouldn't normally use a subwoofer with one." source

Yek's write-up

JMPRE-1 OD1 (based on Marshall JMP-1 preamp)

Models:

1. OD1 mode
2. OD1 mode with Bass Shift engaged
3. OD2 mode
4. OD2 with Bass Shift engaged

Volume, Gain, Bass, Mid, Treble, Presence, Bass shift

Fractal Audio:

1. "The power amp is based on a typical Marshall 100 watts power amp of the same era."
2. "The JMP-1 tone controls have more range than the actual preamp. The preamp has about +/- 8 dB for each tone control while the model has the standard +/- 12 dB."

Yek's write-up

JR BLUES (based on Fender Blues Junior)

Models:

1. Fat switch disabled
2. Fat switch enabled

Cab: Fender 1x12 (Eminence, Jensen C12N, P12R)

Bass, Middle, Treble, Gain, Volume, FAT button (boosts gain and midrange frequencies), Reverb

Fractal Audio:

1. "The Blues Jr. amp has a fixed presence circuit." source
2. "The Eggie is very similar to a Blues Jr. Basically the same preamp with some minor tweaks." source

Yek's write-up

JS410 CRUNCH ORANGE (based on Marshall JVM410HJS)

Models:

1. Crunch Orange: based on a JCM 2203
2. Crunch Red: based on a modded JCM 2203
3. Lead Orange: more gain
4. Lead Red: even more gain

Cab: Marshall 4x12 (V30 and G12H)

Volume, Gain, Bass, Middle, Treble, Master, Presence, Resonance, noise gate, Mid-Shift (around 650hz off and around 500hz on)

Fractal Audio:

1. "Joe said he puts all the tone controls at around 10:00." source
2. "The JVM has a huge plate resistor on the cathode follower, the JS does not." source

Yek's write-up

JAZZ 120 (based on Roland Jazz Chorus 120)

Model:

1. single model

Cab: Roland 2x12 ("silver" AlNiCo)

Volume, Bass, Mid, Treble, Bright switch, Distortion, Chorus, Reverb

Yek's write-up

LEGATO 100 (based on Steve Vai's Carvin Legacy VL100)

Model:

1. Lead channel

Cab: Carvin 2x12 or 4x12 (V30)

Lead channel: Presence, Treble (11kHz), Mid (650Hz), Bass (80Hz), Drive, Volume

Fractal Audio:

1. "The thing that makes a Legacy unique is the tone stack. It uses a "James" tone stack which is more like hi-fi tone controls." source
2. "Adds the "Legato 100" model based on Steve Vai's Legacy 100. This model is unique in that it uses a Baxandall (sometimes called a "James") tone stack. More often used on tube hi-fi gear the controls are less interactive than a typical guitar amp tone stack and impart a different tonal quality." source
3. "The Legato 100 is based on a one-of-a-kind version owned by a certain Californian guitar player. It is a very dark amp. Part of this is due to the tapers on the tone pots. With everything at noon the tone stack looks like a highshelf with a good amount of high frequency cut. The tone stack is a Baxandall which is more common in hi-fi gear than guitar amps. It lends a unique character to the tone." source
4. "SV's personal settings are: Drive: 7.5, Bass: 6, Mid: 4, Treble: 8, Presence: 8. I had to increase the Mid control on the model to about 5 to match the amp which indicates the mid pot on the amp was greater than spec. This is not unusual. Typical consumer-grade pots have pretty poor tolerance in both end-to-end resistance and resistance at the midpoint." source

Yek's write-up

MATCHBOX D-30 (based on Matchless DC-30)

Model:

1. Channel 1 (12AX7) with Master Volume bypassed

Cab: Matchless 2x12 (25w G12M and 30w G12H)

Channel 1: Volume, Bass, Treble. Shared: Cut and bypassable Master

Channel 2 (not modeled): Volume, Tone. Shared: Cut and bypassable Master

Fractal Audio:

1. "The DC-30 is basically an AC-30 copy. The voltages are a bit different but the topology is nearly identical. However, IMO, it does sound better. Not sure why. Perhaps the better quality components. AC-30's have kind of crappy OTs." source
2. "My favorite "Class-A" amp model by far." source
3. (about channel 2) "The switch selects the coupling capacitor between the EF86 and the volume pot." source

Yek's write-up

MR Z HWY 66 (based on Dr. Z Route 66)

Model:

1. single channel

Cab: Dr. Z 2x12 (V30 and G12H)

Volume, Bass, Treble

Yek's write-up

MR Z MZ-38 (based on Dr. Z Maz 38 SR)

Model:

1. single channel

Cab: Dr. Z 1x12 (G12H)

Volume, Master, Bass, Mid, Treble, Cut, Reverb on some models

Fractal Audio:

1. "Dr. Z is the quintessential country amp." source"
2. "IMO the designs are poor because... wait for it... they exhibit a papery buzz. The problem with most cathode biased Class A amps is, 1: they aren't really Class A (more like hot Class AB) and 2: They go into Class B operation when they are overdriven. The cathode capacitor charges up and the bias point shifts dramatically. This causes lots of crossover distortion (papery buzz). It's worse on lower notes because lower notes have more energy and charge the cap more. The is probably the reason Leo Fender switched to fixed bias amps with negative feedback. Fixed bias is just that, the bias point is fixed so the amp doesn't shift into Class B operation when overdriven (not as much anyways, depends on the bias circuit, grid stoppers, etc.). Negative feedback linearizes the amp and reduces the crossover distortion (at the expense of gain). That's why the buzzing went away when you increased negative feedback. Crossover distortion is a unique sound. For cleaner sounds it tends to be objectionable. For overdriven sounds some find it desirable. EVH ostensibly liked his amps biased cold to get some crossover distortion. There are even some amps that have circuits to intentionally generate crossover distortion. Some distortion pedals also do this. Lowering the Cathode Resistance reduces the crossover distortion as it keeps the amp in Class A operation longer but the tubes run hotter and don't last as long. This is not a problem with our virtual amps though. I forget the actual values but I'm pretty certain if you look at the Cathode Resistance value for those amps it's pretty high. This means the amps are biased somewhat cold to begin with and shift to very cold as soon as overdriven. Then there's shared vs. split cathode. If you look at the schematics on the web the Maz-38 is shared cathode. I could never get the model to sound exactly like our reference amp. Finally I traced the entire circuit and our particular amp is a split cathode. As soon as I changed the model to split cathode it was spot on. This is not exposed to the user though (there's a hidden shared/split switch). Our particular amp says "Humbucker" inside the chassis. Not sure if the difference in the cathode circuit is because Dr. Z likes split cathode for humbucking guitars or what." source

Yek's write-up

MR Z MZ-8 (based on Dr. Z Maz 8)

Model:

1. single channel

Cab: Dr.Z 1x12 (G12H)

Volume, Master, Bass, Mid, Treble, Cut, Reverb, Pentode/Triode switch

Fractal Audio:

1. "Dr. Z is the quintessential country amp." source

Yek's write-up

NUCLEAR-TONE (based on Swart Atomic Space Tone)

Model:

1. single channel

Cab: Swart 1x12 (Mojotone BV-25m)

Volume, Tone (model: Treble), Reverb, Tremolo

Fractal Audio:

1. "It's unique character comes from the PI. It's a cathodyne phase inverter so it doesn't drive the grids as hard." source
2. "The real amp is known for it's tremolo so that's why we used the bias trem on the preset. Bias trem works by modulating the power tube grid bias. One of the side-effects is that the effect becomes less pronounced as you play harder which makes it basically "auto ducking". Also since it's modulating the bias it gives an almost Univibe like effect since the phase changes a bit too." source

Yek's write-up

ODS-100 CLEAN (based on Dumble OD Special)

Model:

1. Clean: based on HRM circuit, Clean channel
2. Ford: based on schematics of Robben Ford's #102 Dumble, Overdrive channel, with Pre Amp Boost (PAB) disengaged
3. Ford Mid-Boost: idem, Overdrive channel, with PAB engaged and Mid switch engaged
4. Ford PAB: idem, Overdrive channel, with PAB engaged and Mid switch disengaged
5. HRM: based on HRM circuit, Overdrive channel, Mid switch disengaged
6. HRM Mid: based on HRM circuit, Overdrive channel, Mid switch engaged

Cab: Dumble 2x12 or 4x12 (G12-65, EVM)

Volume (Clean), Bass, Middle, Treble, Overdrive Level, Ratio, Volume (Overdrive), Master Volume, Presence, Bright switch, Mid boost switch, Jazz/Rock switch, Pre Amp Boost (PAB)

Fractal Audio:

1. "The ODS100 has two drive controls, one is right at the input, the other is in the lead boost section."
2. "I hate to admit it but there is something special about a real Dumble. I don't know what it is but there is something in the voicing. The various clones I have are cool and have their own thing going but they don't sound like the Dumble. Hard amp to play though. Very unforgiving but tremendous clarity." source
3. "They call HRM "Hot Rubber Monkey" but what it really means is "Hot Rod Marshall"." The HRM Dumbles have a fixed Marshall tone stack at the output of the lead channel. This gives a little scoop to the mids." source
4. "My Dumble is S/N 0213 IIRC. It's an EL-34 ODS HRM." source
5. "The ODS-100 Ford 2 model is not based on the HRM model with the HRM tonestack removed. Whether or not the model matches any particular Dumble is unknown as we have not been able to procure a non-HRM Dumble yet. The model is based on schematics that were given to us that supposedly accurately represent Robben Ford's Dumble. Whether or not the schematics are accurate I do not know. The voltage divider at the output of V1B is set to 0.078 which is based on the values that are indicated on the schematic for the set-point of the trimmer. As no two Dumbles are identical it stands to reason that one person's interpretation of the ideal Dumble voicing may not agree with another's. Since V1 is running clean you can get more gain by simply increasing Input Trim. It will have basically the same effect as increasing the trimmer."
6. "A signal divider, which is more correctly called a voltage divider, is calculated by taking the resistance to ground divided by the sum of the resistances. In this case the voltage divider would be 26.7/317 = 0.084. This is very close to the values that we were given (which yield 0.078). Our model also uses local feedback on V1B (which is about 2-3 dB less gain) and accounts for the voltage divider's affect on the AC load line. In fact all stages in a Dumble typically have an AC load-line that's different than the DC load-line due to the load resistance being significant in relation to the plate resistor. Since V1A and V1B run clean (linear) Input Trim will accomplish the same thing as increasing the trimmer into the drive stages. This is because a linear system is commutative (see any introductory Signals and Systems text for properties of linear systems). The commutative property is where A x B = B x A. Therefore it does not matter if the gain is before or after the linear stages."
7. "The Mid switch, sometimes labeled "Deep", shorts out the 390 pF cap in the tone stack (which is in series with a 2 nF cap). All that is left then is the 2 nF cap. With PAB active this lowers the lowcut frequency." source
8. "Maybe the best clean model IMO. You have to really crank the MV though (just like the real amp)." source
9. "The only amps with a bright cap on the MV are Dumbles and their various clones/derivatives. This was/is done to compensate for the lack of a buffer for the fx loop. The loop send is taken right off the MV which means the output impedance is very high. Any significant length of cable will then attenuate the highs due to the cable capacitance. The bright cap boosts the highs to compensate. It's the same idea as a bright cap on your guitar's volume knob. Crude. FWIW, this is a terrible loop design but "it's a Dumble" so it's all part of the mystique. Dumble then released the "Dumbleator" which is nothing more than a buffer and recovery in an external box. Dumble fanatics, of course, claim that to have the true Dumble experience you MUST use the Dumbleator which is just another load of BS." source

Yek's write-up

PVH 6160 BLOCK (based on Peavey "Block Letter" EVH 5150)

Model:

1. Lead channel

Cab: Peavey 4x12 (Sheffield 1200)

• Pre and Post Gain, Low, Mid, High, Resonance, Presence, Bright and Crunch switches (Rhythm channel only)

Fractal Audio:

1. "I have a "holy grail" Block Letter 5150 (supposedly). It sounds way better than most 5150s for some reason which is a good thing for you guys. I think it's partly due to the fact that it has a bias mod so it's biased a bit warmer than a stock version." source

Yek's write-up

PVH 6160+ LEAD (based on Peavey 6505+ / EVH 5150-II)

Models:

1. Rhythm channel, Crunch and Bright switches pressed "in"
2. Rhythm channel, Crunch and Bright switches "out"
3. Lead channel

Cabs Peavey 4x12 (V30)

Rhythm channel: Pre (gain), Bright switch (6dB at 2kHz), Crunch switch, Low, Mid, High, Post (Master), Resonance, Presence

Lead channel: Pre (gain), Low, Mid, High, Post (Master), Resonance, Presence

Fractal Audio:

1. "Chris Quigley's 6505 was the reference amp. It's my amp now. It's a very good sounding one." source
2. (about channel 1) "Someone was looking for that amp model recently so I dug our 6505+ out and was surprised at how nice that channel sounds." source
3. "A 6505+ is identical to a 5150 except it has no bright cap. Use the 5150 model and turn off the bright switch." source

Yek's write-up

PLEXI 100W 1970 (based on Marshall Plexi)

Models:

1. 1970 100 watts, EL34
2. 1969 100 watts, High Treble channel
3. 1969 100 watts, jumpered channels
4. 1969 100 watts, Normal channel
5. 1972 50 watts, 6550 power tubes, jumpered channels
6. 1981 50 watts JMP with master volume
7. 1972 50 watts, EL34, High Treble channel
8. 1972 50 watts, EL34, High Treble channel (2nd triode stage has a 0.68uF cathode bypass capacitor, which was added in the early 70’s and gives a slightly brighter tone)
9. 1972 50 watts, EL34, jumpered channels
10. 1972 50 watts, EL34, Normal channel

Cab: Marshall 4x12 (G12M, G12H)

Volume (jumpered channels: Volume Normal and Volume Treble), Bass, Middle, Treble, Presence, Master (Plexi 2204 only)

Fractal Audio:

1. "1970 Marshall 1959SLP 100 has a darker, smoother sound than earlier Plexis."
2. "One of the first mods people make to real 'Plexi' Marshalls is to "clip the bright cap". The bright cap varied over the years, supposedly depending on what was lying around in the shop. The model defaults to the bright cap in the circuit. If you turn off Bright you're effectively clipping the bright cap. The bright cap in Marshalls can be very bright and harsh. However, if you crank the Master you might find the extra brightness helps compensate for the power amp getting darker."
3. "It's the way a Plexi is supposed to sound. That's due to the cathode follower. That raspiness helps it cut through in a mix. I own three of them and they are that fizzy." source
4. "Don't be afraid to turn the bass all the way down or the treble all the way up. Just like with the actual amp. For example, on the normal channel of a Plexi most people turn the bass way down. Otherwise it's too flubby." source
5. "My settings for a "typical" Plexi tone are Bass: 2, Mid: 8, Treble 7.5. Adjust Presence to taste." source
6. "Try the Plexi 100W 1970 with Factory Cab 54. Be sure to dial it in like you would in 1970, i.e. turn the Mid, Treble and Presence way up; turn Norm Drive and Bass down a bit." source
7. About Plexi Normal: "The topology of that model does not support a bright cap and the actual amp has no bright cap." source
8. (about getting the Boston/Rockman sound) "Plexi Jump. Everything on 7. Put a Filter block in front: Type: Peaking, Freq: ~800 Hz, Q: 0.707, Gain 12 dB." source
9. (favorite classic Plexi) "50w 6550." source
10. (Plexi 100w 1970) "I've never cared for that model nor the actual amp. IMO it doesn't have enough feedback (100K off the 4-ohm tap). Some amps of that era had 47K off the 4-ohm tap. Some had 47K off the 8-ohm tap. Some had 100K off the 8-ohm tap and some even had 47K off the 16-ohm tap! IOW all over the map. Bottom line: try adjusting Negative Feedback. I always raise it up a bit with that model. Around 4 or so." source
11. "What you are hearing is output transformer high frequency resonance. Old Plexis didn't do this because they had good transformers. New transformers are crappy and resonate at the cutoff frequency because they are underdamped. This causes a raspy, fizzy texture to the distortion. The transformer resonance is adjustable but the parameter isn't exposed to the user. When you turn it up you get that same squishy rasp that you are hearing. For the Plexis I have the damping set to flat with no resonance because that's how our vintage Plexis measure. Our 50W is a little underdamped but people complain about raspy high frequencies so I erred on the safe side." source

Forum discussion about the Plexi 2204 model

Yek's write-up

PLEXI 2204

Fractal Audio:

1. "Based on a 1981 JMP 50W Master Volume head."

PLEXI 50W HIGH 2

Fractal Audio:

1. "Similar to Plexi 50W High 1 except the second triode stage has a 0.68uF cathode bypass capacitor. The second bypass capacitor was added in the early 70’s and gives a slightly brighter tone."

PORTA-BASS (based on Ampeg Portaflex bass amp)

Model:

1. single channel

Cabs SVT 8x10

Notes: See SV Bass

Compression, Limiter, Gain, Bass, Mid, 5-way Midrange Frequency switch, Ultra Hi and Ultra Lo switches, Treble, Master Volume

PRINCE TONE 5F2 (based on Fender Tweed Princeton, 5F2-A)

Model:

1. single channel

Cab: Fender 1x10 (C10n)

Volume, Tone

Yek's write-up

PRINCE TONE AA964 (based on Fender silverface Princeton without reverb, AA964)

Model:

1. single channel

Volume, Bass, Treble

Fractal Audio:

1. "Based on a Fender AA964 Princeton. This particular amp is an early CBS “Silverface” but still using pre-CBS design and components."

See above

PRINCE TONE REVERB (based on '66 Fender blackface Princeton with reverb, AA964)

Model:

1. single channel

Volume, Bass, Treble, Reverb

Fractal Audio:

1. "A Princeton Reverb has an extra gain stage due to the reverb recovery. Hence it has more gain." source

RECTO1 ORANGE MODERN (based on Mesa's two-channel Dual Rectifier)

Models:

1. Recto1: Orange channel (two modes) and Red channel of the original two-channel Rectifier
2. Recto2: Orange and Red channels, both in Vintage and Modern mode, of the newer three-channel Rectifier

Cab: Mesa 4x12 (V30)

Gain, Master, Bass, Middle, Treble, Presence

Fractal Audio:

1. "For an amp like the Recto you want the Master below 5.0." source
2. "The reason you're hearing the highs rolled off is because the Master is too high. As you increase the Master the highs get muffled. 7.02 for the Recto Master is ridiculous and will sound like crap." source
3. "Note that the Orange Modern and Red Modern models have no negative feedback and therefore the Presence control is a Hi Cut control." source
4. "A typical Recto cabinet has a resonant frequency a little over 100 Hz." source
5. "The unique thing about a Dual Recto tone stack is that the Presence control is part of the tone stack. So the Recto tone controls also interact with the presence control." source
6. "Rectos don't have a Depth control and even if they did it wouldn't do anything in Modern Red mode since that mode has no negative feedback. When you put a Recto into Modern Red mode it opens a relay which removes the NFB." source
7. "Real Rectos are bassy/fizzy beasts but that tone works great for certain genres." source
8. "If you are using the Modern modes be very careful with the MV. If you turn it up too high it will flub out really quick. If in doubt reduce the MV. Compensate with the Level control." source
9. "The Modern mode in Rectos has no negative feedback so there's a huge bass boost from the speaker impedance. Fortunately you can reduce this by reducing the LF Resonance on the Spkr tab which is something you can't do with the real amp without trying different speakers or cabinet." source
10. "Depth works by varying the negative feedback at low frequencies. There is no NFB in the Modern Red mode so the Depth knob won't do anything. NFB is set to 0.01 just to fool the GUI into displaying Presence instead of HiCut below the left knob." And: "When you put a Recto into Modern Red mode it opens a relay which removes the NFB." source And: "That is intentional. It's a software trick to force the model not to use Hi Cut but Presence instead. That amount of feedback is inaudible." source
11. "All passive tone controls interact and all the Axe-Fx tone stacks replicate this behavior. The unique thing about a Dual Recto tone stack is that the Presence control is part of the tone stack. So the Recto tone controls also interact with the presence control." source
12. "If you are using the Modern mode then it's all about the Spkr page. Since that mode has no negative feedback the speaker resonance has a tremendous effect on the sound. Adjust LF Res, Freq and Q to get desired response." source
13. "Another thing with the Modern modes is that the power amp distorts early (again since there is no negative feedback and, therefore, the power amp has a lot more gain). At 9:00 on the Master the power amp is distorting (it's probably a linear taper pot for the ol' "Wow, this amp is loud bro!"). The taper of the Axe-Fx Master Volume is not the same and you have to turn it up higher to get the same amount of virtual power amp distortion. Another thing is that if you put ANYTHING in the loop of a Recto it changes the tone significantly. Even just a short cable. All the models were made with the loop off. And another thing is that Rectos changed a lot. I have three of them and they all sound completely different. One of them has a different value Gain pot than the others. One of them has a different value bright cap than the one with the same Gain pot. Since the gain pot and bright cap interact this makes a HUGE difference. Experiment with the Bright Cap value. The Recto1 models are based on our Rev. F (IIRC, whatever the desirable ones are). The Recto2 models are based on the latest version." source
14. "We have three of them, a single and two duals." source
15. "If you want that Recto crunch but not so flubby and fizzy try the SOLO models." source

Yek's write-up

RUBY ROCKET (based on Paul Ruby Rocket)

Models:

1. Bright switch on
2. Bright switch off

Cab: 1x12 (Alnico, G12M)

Volume, Bass, Treble, Cut, Bright switch

Fractal Audio:

1. "The Ruby Rocket is not the same as an actual Trainwreck Rocket. There are topology differences and the amps don't sound the same." source
2. "Ruby Rocket is based on a Paul Ruby Rocket which is based on a TW Rocket but with some notable differences." source
3. "The Bright switch changes a coupling cap and the treble cap in the tone stack. This cuts the bass, shifts the midrange and lowers the gain slightly. That's why there are two separate models. Otherwise you would just engage the Bright switch under the Treble knob."
4. "The Ruby Rocket has a bright switch but it's actually a channel select (selects the bright channel)."

Yek's write-up

SV BASS 1 (based on Ampeg SVT bass amp)

Model (in the Axe-Fx III):

1. Fractal Audio's SV Bass model prior to the change in firmware Ares 2.05 and later for the Axe-Fx III
2. Based on a 1970 Ampeg SVT with 6550 power tubes and the midrange switch in position 3

Notes: on the Axe-Fx II (firmware Ares) these models are reversed. source

Cab: SVT 8x10

Volume, Bass, Mid (and Mid Frequency), Treble, Master, Ultra Lo / Hi switches

Yek's write-up

SHIVER CLEAN (based on Bogner Shiva 20th Anniversary)

Model:

1. Clean channel
2. Lead channel

Original controls:

• Shared: Master, Presence, Excursion, Boost switch
• Clean channel: Volume, Bass, Treble, Bright switch
• Lead channel: Gain, Volume, Bass, Middle, Treble, Shift EQ, Bright switch, Mode switch

Cab: Bogner 1x12 or 2x12 (Classic 80, V30)

Cliff:

1. "People think Bogners are dark but they really aren't. The reason they seem that way is the pot tapers. Most people assume knobs should be set somewhere around noon. If you do this on a Bogner it's like turning the treble way down on a Marshall. Close your eyes and adjust the tone controls with your ears. Don't be afraid to turn them way up or way down." source
2. "Human nature is to put the knobs near noon. We are reticent to deviate much from noon. Amp designers exploit this and use different tapers to change the sound of their amps WITH THE KNOBS AT NOON. A prime example are Bogner amps. Everyone says "Bogner amps are dark". No they aren't. But he uses a Log10A taper for the treble pot. It's a standard Marshall tone stack. Usually a linear taper pot is used for the treble. The treble knob at 5.0 (noon) on a Bogner is equivalent to the treble knob at 1.0 on a Marshall. People put the knob at 5.0 and go "wow, this amp is dark". No it isn't. If you turned the treble up to 8 or 9 it would sound a lot like a Plexi but humans are reticent to turn the knobs to extremes. Amp designers know this and exploit it to give their amps a "signature sound"." source
3. "The original Shiva models were based on a borrowed amp. We now have a 20th Anniversary Shiva (with KT88s) and the new models are based on that amp. We did notice that this amp has less gain than the one used originally but the model is faithful to the amp." source

Yek's write-up

SOLO 100 CLEAN (based on Soldano SLO-100)

Model:

1. Normal channel: Clean mode
2. Normal channel: Rhythm mode
3. Overdrive channel

Cab: Soldano 4x12 (Eminence)

Original controls:

• Gain, Bass, Middle, Treble, Master, Presence, Bright switch (Normal channel only), Depth (with Depth mod)

Cliff:

1. "The SLO-100 is the loudest amp I've ever used. It feels like there's a small nuclear explosion going off inside when ever you hit a power chord. It's a wicked amp but not something I would recommend for anything but large gigs. If you like the SLO-100 model you might want to try the Recto models too. It's not widely known but the Rectifier preamp is a derivative of the SLO-100. Some minor changes but the basic topology is identical."
2. "I have a really good SLO-100. An original black faceplate version. Pristine condition. That amp was one of the primary amps used in the G2 modeling development. It was by studying that and a really nice JCM-800 that I finally figured out the secret to cathode follower." source
3. "Mine doesn't have the depth mod but I used the values from the schematic I have and I believe the schematic is correct." source
4. "SLOs are brittle at low volumes. When you crank them up it smooths out. The problems is at cranked volumes they can kill small animals." source
5. "The key to an SLO100 is to run the MV high so that the mids thicken up. Otherwise it's a shrill mess. In certain contexts with the right IR it can be a cool sound." source
6. "Note that the knobs on '5' on the Axe-Fx correspond to '6' on an SLO because they go to 11. 'Noon' on an SLO isn't actually the knobs at half-way. The range of the knobs is like 8:00 to 6:00 as opposed to 7:00 to 5:00. They're biased clockwise." source
7. "Another caveat when comparing amps: many times the knobs aren't "centered". IOW if you put the Treble knob at noon it isn't actually at 50%. You can see this by turning the knob all the way down and all the way up. It may not be symmetrical. This happens when the pots don't have a flat spot and/or the pot is rotated within the mounting hole. Or in the case of an SLO100 it is intentional. On an SLO100 all the way down is around 8:00 and all the way up is 6:00 so 50% is around 1:00 not noon." source
8. "Many people find SLOs too bright. The "Warren Haynes" mod is a popular mod to reduce the brightness." source
9. "Those amps are all designed to get their character from power amp distortion. If you don't push the power amp all you are hearing is the preamp which is voiced to be trebly. The power amp then compresses the highs and the sound gets fatter." source
10. "If you want that Recto crunch but not so flubby and fizzy try the SOLO models. They're much brighter so I turn the treble down quite a bit." source
11. "SLO 100s are NOT smooth amps. They are nasty, aggressive things that you have to crank the MV." source

Yek's write-up

SOLO 88 CLEAN (based on Soldano X88R preamp)

Model:

1. Clean channel
2. Rhythm channel
3. Lead channel

Original controls:

• Gain, Bass, Middle, Treble, Volume, Bright switch (Clean and Rhythm channels)

Cliff:

1. "Solo 88 RHY is based on an X88R since the rhythm channel of an X99 is identical to an SLO-100. FWIW, I have two X88Rs and the model agrees with both." source

Yek's write-up

SOLO 99 CLEAN (based on Soldano/Caswell X99 preamp)

Model:

1. Clean channel
2. Lead channel

Original controls:

• Gain, Bass, Middle, Treble, Volume, Bright switch

Cliff:

1. "The rhythm channel of an X99 is identical to a SLO 100." source
2. "Power amp: same as SLO100." source

Yek's write-up

SPAWN NITROUS 1 (based on Splawn Nitro)

Model:

1. Overdrive channel in OD-1 (Rhythm) mode
2. Overdrive channel in OD-2 (Lead) mode

Firmware release notes: "Based on a Splawn Nitro with KT-88 power tubes".

Cab: Splawn 4x12 (G12M, G12-65, V30)

Original controls:

• Resonance, Presence, Bass, Middle, Treble, Master, Gain

Yek's write-up

SPAWN Q-ROD OD1-1 (based on Splawn Quickrod)

Model

1. Overdrive channel, Rhythm mode, 1st gear (Plexi)
2. Overdrive channel, Rhythm mode, 2nd gear (hot-rodded JCM 800)
3. Overdrive channel, Rhythm mode, 3rd gear (super hot-rodded 800)
4. Overdrive channel, Lead mode, 1st gear
5. Overdrive channel, Lead mode, 2nd gear
6. Overdrive channel, Lead mode, 3rd gear

Cab: Splawn (G12M, G12-65, V30)

Original controls:

• Presence, Bass, Middle, Treble, Volume, Gain, Mode

Cliff:

1. "The reason Splawns sound weird is because the tone stack is plate driven. You lose the cathode follower compression and the high source resistance of the plate alters the tone stack frequency response. The plate driven tone stack in the Splawn reduces the highs considerably. You can see this is you run Tone Stack Calculator for the Marshall tone stack and increase the source resistance." source
2. "OD2 switches in a cathode bypass cap which increases the gain of that stage." source
3. "The Quick Rod is a bit odd in that the Drive pot is linear taper. Most amps use an audio taper pot. This means that at noon the amp is nearly at full gain. Not sure why they did it that way but it is what it is." source

Yek's write-up

SUHR BADGER 18 (based on Suhr Badger 18)

Model

1. single channel

Cab: Suhr 1x12 or 2x12 (V30, G12M)

Original controls:

• Bass, Middle, Treble, Gain, Power (controls Power Scaling), Drive (acts as Master with Power at 10)

Cliff:

1. "The Badgers were MIMIC'd with power scaling at full. The knobs are a bit confusing on a Badger. The knob closest to the input jack is labeled "Gain". It is equivalent to the Drive knob in the Axe. The knob labeled Drive is the Master Volume." source
2. "IMO the designs are poor because... wait for it... they exhibit a papery buzz. The problem with most cathode biased Class A amps is, 1: they aren't really Class A (more like hot Class AB) and 2: They go into Class B operation when they are overdriven. The cathode capacitor charges up and the bias point shifts dramatically. This causes lots of crossover distortion (papery buzz). It's worse on lower notes because lower notes have more energy and charge the cap more. The is probably the reason Leo Fender switched to fixed bias amps with negative feedback. Fixed bias is just that, the bias point is fixed so the amp doesn't shift into Class B operation when overdriven (not as much anyways, depends on the bias circuit, grid stoppers, etc.). Negative feedback linearizes the amp and reduces the crossover distortion (at the expense of gain). That's why the buzzing went away when you increased negative feedback. Crossover distortion is a unique sound. For cleaner sounds it tends to be objectionable. For overdriven sounds some find it desirable. EVH ostensibly liked his amps biased cold to get some crossover distortion. There are even some amps that have circuits to intentionally generate crossover distortion. Some distortion pedals also do this. Lowering the Cathode Resistance reduces the crossover distortion as it keeps the amp in Class A operation longer but the tubes run hotter and don't last as long. This is not a problem with our virtual amps though. I forget the actual values but I'm pretty certain if you look at the Cathode Resistance value for those amps it's pretty high. This means the amps are biased somewhat cold to begin with and shift to very cold as soon as overdriven. One reason I like the AC-20 is that it runs the tubes hotter and exhibits less crossover distortion. The worst amp in this regard is the Badger 18. The cathode resistors are very large and the amp shifts into Class B operation early causing a spitty, buzzy distortion quality. This amp, however, is liked by many so that just goes to show that some people like that. It's like fuzz pedals. Some people like that spitty sound. I personally don't like it. Then there's shared vs. split cathode. If you look at the schematics on the web the Maz-38 is shared cathode. I could never get the model to sound exactly like our reference amp. Finally I traced the entire circuit and our particular amp is a split cathode. As soon as I changed the model to split cathode it was spot on. This is not exposed to the user though (there's a hidden shared/split switch)." source
3. "The Badger doesn't have a Bright switch."source

Yek's write-up

SUHR BADGER 30 (based on Suhr Badger 30)

See above

SUPER VERB NORMAL (based on '64 Fender Super Reverb, AB763)

Model:

1. Normal channel
2. Vibrato channel

Cab: Fender 4x10 (C10R, C10Q, P10R)

Original controls:

• Volume, Bass, Middle (Vibrato channel only), Treble, Bright switch, Reverb, Vibrato

Cliff:

1. "I modeled the Super with V1 pulled as most people pull V1 so the amp has more grunt. Turn down the MV to make it cleaner"
2. "The Super Reverb model is based on the amp with V1 removed (which is a common mod). This increases the level into the power amp by about a factor of two." source
3. "The Super Reverb model is "Diaz Modded". IOW, I pulled V1. This gives the amp a lot more gain so it's not surprising you're getting breakup at around 1.5. You can un-mod the model by turning down the MV Trim to around 0.5." source
4. "A Pro Reverb is basically identical to a Super Reverb except for the speakers (and faceplate)." source And: "The Blackface Pro Reverb, model AA165, was virtually identical to the AB763 Super Reverb except for the speakers and tone stacks. If you use the Super Verb model and set the Tone Stack type to Blackface you'll basically have a Pro Reverb. Set the Mid control fairly high to emulate the fixed 6.8K mid resistor. I'd say around 7 or 8." source
5. (about blackface versions) "Not a huge change with the Silverfaced versions. They're a little cleaner and brighter but the topology is the same. Some minor circuit changes here and there. Same transformers. The biggest change, IMO, was changing the PI resistors to 47K which gives you a little less gain in the PI." source
6. "The Super Reverb is really just a 50W version of a Twin Reverb with different speakers." source

Yek's write-up

SUPERTWEED (custom "Tweed" model)

Model:

1. custom Fractal Audio model

Yek's write-up

SUPREMO TREM (based on Supro 1964T)

Model:

1. single model

Cab: Supro 2x12

Original controls:

• Volume, Tone

Yek's write-up

TEXAS STAR CLEAN (based on Mesa Lone Star Classic)

Model:

1. Clean channel
2. Lead channel

Cab: Mesa 2x12 (C90)

Original controls:

• Drive, Gain, Treble, Mid, Bass, Presence, Master, Voicing

Yek's write-up

THORDENDAL MODERN (based on Mesa Dual Rectifier)

Model:

1. Modern mode
2. Vintage mode

See Recto

Cliff:

1. "What happened was this: the old Recto models weren't terribly accurate. When G3 came out the models were accurate but Fredrik contacted me and said something like "ahhhhh, I loved the old Recto model". So I took the old Recto models and made them "Thordendal" models." source

Yek's write-up

TREMOLO LUX (based on blackface Fender Tremolux, AA763)

Model:

1. Normal channel
2. Vibrato channels

Cab: Fender 2x10

Original controls on Vibrato channel:

• Volume, Bright switch, Treble, Bass, Tremolo controls

Yek's write-up

TUBE PRE

Model:

1. single model

Cliff:

1. "The Vintage tone stack is a passive EQ model but it has a flat response when the controls are at noon. If you want "active" EQ you need to set the type to Active." source
2. "If you only need power amp modeling, for example when using an external pre-amp through the Axe-Fx, use the Tube Pre model. It uses the Vintage tonestack which is flat when the tone controls are at noon."
3. "The "Vintage" tone stack is flat. The Tube Pre model uses the Vintage tone stack." source

Yek's write-up

TWO STONE J35 (based on Two-Rock Jet 35)

Model:

1. Lead mode, Preamp Bypass (PAB) engaged
2. Lead mode, Preamp Bypass off

Cab: Two Stone 2x12 (G12-65)

Original controls:

• Treble, Mid, Bass, Gain, Master, Lead Gain, Pull Bright

Cliff:

1. "Yes, it's very smooth but there's this unique chirp or something that I've never heard in an amp before. When you hit the note there's this blast of high end that rapidly decays so it has an almost vocal quality. The frequency shaping is very different than most other amps." source
2. "The Two Rock is the most unique amp I've ever modeled. Almost like a violin but with this really cool chirp on the pick attack." source

Yek's write-up

USA BASS 400 1 (based on Mesa/Boogie Bass 400 bass amp)

Model:

1. Bass Shift disabled
2. Bass Shift engaged

Cab: Mesa bass cab

Original controls:

• Bass, Middle, Treble, Pull Bright, Bass/Mid/Treble Shift, 7-band GEQ

Yek's write-up

USA CLEAN (based on Mesa/Boogie Mark IV)

Model:

1. Rhythm 1 channel
2. Rhythm 2 channel
3. Lead channel, Voicing: Harmonics, Pull Bright engaged
4. Lead channel, Voicing: Mid Gain, Pull Bright engaged
5. Lead channel, Voicing: Harmonics, Pull Bright off
6. Lead channel, Voicing: Mid Gain, Pull Bright off

Cab: Mesa 1x12 (C90, V30)

Original controls:

• Gain, Lead Drive, Treble, Bass, Mid, Presence, Master. Pull Bright: Rhythm 1 and Lead channel. Pull Fat: Rhythm 2 and Lead channel. Presence Shift: Rhythm 2 and Lead channels, graphic EQ, Pentode/Triode switch, Class-A/Simul-Class switch, Voicing switch (Mid Gain / Harmonics), Variac

Cliff:

1. "The MK V is basically a compendium of previous Mesa amps. There may be minor differences in tone due to circuit layout but nothing a few tweaks to the EQ can't fix." source
2. "Having owned multiple Mark IV's, multiple Triaxis's and a variety of other Boogie products, I can tell that the Mark series in general are a bitch to dial in. Once you figure them out though they are great amps. IMO, the key to a MKIV is to use the TMB to get the feel and the EQ to get the tone."
3. "If it isn't Mid Gain then it's Harmonics." source
4. "The Depth knob is inactive on that amp model. The real amp doesn't have one either." source
5. "Fat and Presence shift work as the real amp." source
6. "USA Clean is based on the MKIV." source
7. "With the presence control at noon it's roughly neutral. Turn it down and you are actually boosting bass and reducing treble." source
8. "I have a Mark IIC+, a Mark IV, a Mark V and a Triaxis. They're all completely different. Mesa always says things like "sounds the same as a IIC+" but the circuits are different and, probably most important, the knob tapers are completely different." source
9. "The key to a good Boogie sound, IMO, is the Fat Switch. This is the treble Pull Shift on the IIC+ and the Pull Fat on the Mark IV. Mesa knew this and the Lead 2 modes on the Triaxis all had the treble shift engaged by default." source
10. "There isn't any way to run the virtual power tubes in triode mode... but you can change the Power Tube Type to "300B" which is a triode. When you run a pentode (or beam tetrode) in triode mode you connect the screen to the anode which effectively defeats the screen. This lowers the output impedance of the plate significantly which, in turn, lowers the output impedance of the amp itself making the voltage output less dependent on the speaker impedance. Using the 300B tube type should get you pretty close." source
11. (about the GEQ) "The range of the sliders is the same as the amp. The taper is not. The amp is much more abrupt since it uses linear taper (should use 'S'-taper)." source
12. (about the difference between the "JP Green" and "USA Clean") "JP has less gain and a much larger midrange potentiometer." source

Yek's write-up

USA IIC+ (based on Mesa/Boogie Mark IIC+ without GEQ)

Model:

1. Lead Master Pull Bright engaged
2. Lead Master Pull Bright off
3. Lead Master Pull Deep engaged
4. Lead Master Pull Deep off

Cab: Mesa 1x12 (C90, EVM)

Original controls: Volume (pull: Bright), Treble (pull: Shift = Fat), Bass (pull: Shift, not modeled), Middle, Presence, Master rhythm (pull: Deep), Lead Drive and Master Lead (pull: Bright)

Cliff:

1. "The mode in the Mark V is based on the later SimulClass version." source
2. "If you want the sound of the non-SimulClass version set Triode 1 Plate Freq to 1350 Hz." source
3. "The Pull Bright on the Volume knob is the classic "Bright Cap" which engages a capacitor across the potentiometer. This is already modeled in the Axe-Fx via the Bright Switch. The Pull Bright on the Lead Master knob engages a 0.22uF cap on the cathode of the last triode in the overdrive circuit. As there is no switch for this in the Axe-Fx it requires a separate model. Cathode caps are very common in tube amps. If the value is large the stage has more gain and the response is relatively flat. If the value is small the stage has more gain at higher frequencies. Amp designers use cathode caps to shape the frequency response. Caps in the range of 0.1 to 1.0 uF are commonly used to reduce bass response. A cathode cap works by decreasing the amount of negative feedback through shunting higher frequencies to ground. This reduced negative feedback increases the gain (and reduces linearity). FWIW the Axe-Fx is the only modeler of which I'm aware that actually models triodes using a feedback technique. Other modelers use static waveshapers. The Axe-Fx triode models incorporate feedback so if there is a virtual cathode cap the stage is less linear in addition to having more gain." source
4. "The IIC+ does not have a gain boost and doesn't need one. There is plenty of gain. The Pull Deep switch engages a large cathode cap on the final triode stage. With Pull Deep off there is actually a shelving response into the power amp (bass is reduced)."
5. (to emulate Pull Shift on the Bass) "Put a Tilt EQ before the amp block with a frequency of 320 Hz and a gain of -3 dB. Set the Level to +3 dB". source
6. "I have a Mark IIC+, a Mark IV, a Mark V and a Triaxis. They're all completely different. Mesa always says things like "sounds the same as a IIC+" but the circuits are different and, probably most important, the knob tapers are completely different." source
7. "The key to a good Boogie sound, IMO, is the Fat Switch. This is the treble Pull Shift on the IIC+ and the Pull Fat on the Mark IV. Mesa knew this and the Lead 2 modes on the Triaxis all had the treble shift engaged by default." source
8. "I always used the Fat switch with the real amp." (IIC+) source
9. "On a Mark IV (at least on our reference amp) all three controls have a Log10A taper. On a Mark V the tapers are different so you get more midrange and treble for the same settings. Channel 3 on a Mark V is virtually identical to the Mark IV Lead channel except for the pot tapers." source
10. "The IIC++ amp model is the same as the IIC+ with different tapers." source

Tips from Cliff: (source)

1. "I begrudgingly dragged the amp out of storage today (as it weighs a metric ton) and repeated the measurements and did some A/B tests. As expected the models are extremely accurate. That being said it is a bear to dial in. Here are some tips:
2. The old version of the model incorrectly referenced the Mark IV tone stack. These tone stacks are identical except for the taper of the mid pot. The IIC+ has a linear pot and the Mark IV has a Log10 pot. I had it backwards in my earlier comments. My guess is that Mesa found that turning the midrange down sounds best (and it does) so they changed the pot taper to do this automatically since noon on a Log10 pot is equal to a 1.0 on a linear pot.
3. Commensurate with (1) I found myself turning the midrange down as well as the bass and turning the treble up.
4. I think the default Master Volume value is a bit high so you may want to turn that down. I've reduced the default for Quantum 2.03.
5. Turn the bright switch on. Every bit of information I've found says that people typically used the Pull Bright on the Volume knob. This is equivalent to the Bright switch under the Treble control on the model. I always turn it on and I've set it on by default for Q2.03.
6. USE THE EQ. The tone stack is pre-distortion which is atypical for a high-gain amp. Tone stacks are almost always post-distortion. Since the tone stack is pre-distortion you need to do your post distortion tone shaping using the EQ. The tone controls set the feel and the distortion texture, the EQ shapes the final tone. I like to do a gentle V-curve.
7. These were my settings for a killer high-gain tone: Model: USA IIC+ / Input Drive: 8.1 / Overdrive: 9-10 / Bass: 1.0 / Midrange: 1.8 / Treble: 8.9 / Presence: 4.5 / MV: 4.0 / Level: -20 dB / Bright Switch ON / 80 Hz: 4.8 / 240 Hz: 2.6 / 750 Hz: -4.5 / 2200: -0.2 / 6600: 0."

Yek's write-up

USA IIC++ (based on James Hetfield's Mesa/Boogie Mark IIC+)

USA JP IIC+ Green (based on Mesa/Boogie JP-2C John Petrucci signature model)

Model:

1. Green: channel 1
2. Red: channel 3
3. Yellow: channel 2

To emulate the “Shred” mode, turn the High Treble control to approximately 3-4 dB (or adjust to taste, you are not limited by a single switch).

Cliff:

1. "The JP amp has a fixed input gain control. The "Gain" control on the amp is actually an Overdrive control. If you use Authentic controls there is no Input Gain on "Gain"." source
2. "Presence Shift is Presence pull. Tone stack effectively has fat switch on." source
3. (about the difference between the "JP Green" and "USA Clean") "JP has less gain and a much larger midrange potentiometer." source
4. "I'm not at liberty to say anything more but JP himself gave the models his stamp of approval." source

USA PRE CLEAN (based on Mesa/Boogie TriAxis preamp)

Model:

1. Rhythm Green
2. Lead 1 Red (TX-4 board)
3. Lead 2 Green
4. Lead 2 Red
5. Lead 2 Yellow

Original controls:

• Drive, Lead Drive, Treble, Middle, Bass, Presence, Master, Dynamic Voice (EQ)

Cliff:

1. "I used a Triaxis for, shoot, I dunno, over a decade before designing the Axe-Fx. I have two of them. So I'd say I'm pretty familiar with the tones. To my ears (and my measurement equipment), the Axe-Fx models are spot-on."
2. "I can nail the sound of my Triaxis now by setting it (Bright) around 9:00 - 10:00." source And: "10 on the Triaxis would be 0 dB on the Bright parameter. Anything below 10 is equivalent to less than noon on the Bright parameter. The "Presence" control on a Triaxis is always a hi cut, it never boosts. The Bright parameter is not an exact match to the Triaxis Presence control though. It is a fixed shelving filter. The Triaxis Presence control is passive so the center frequency changes with the amount of cut. It also changes the load on the plate which distorts the frequency response a bit too. The Presence parameter should be set to 5.00, which is neutral (see the manual for details)."
3. "I have a Mark IIC+, a Mark IV, a Mark V and a Triaxis. They're all completely different. Mesa always says things like "sounds the same as a IIC+" but the circuits are different and, probably most important, the knob tapers are completely different." source
4. "The key to a good Boogie sound, IMO, is the Fat Switch. This is the treble Pull Shift on the IIC+ and the Pull Fat on the Mark IV. Mesa knew this and the Lead 2 modes on the Triaxis all had the treble shift engaged by default." source
5. "Mesa claims it's based on the IIC+ but it's different. The bright cap is different, the mid resistor is much greater, the source impedance of the drive "pot" is different, etc., etc, etc." source
6. (firmware Quantum 7) "The USA Pre models now all use a MarkIV power amp model. The 2:90 power amp is basically the same as a MarkIV and does have a presence shift but it's accessed through a jack on the back (Voicing)." source
7. "I gigged with a Triaxis for years. I never put Dynamic Voice above 1.0. Despite it's name, DV is just an EQ. It's the 5-band graphic EQ from the mark series with the potentiometers replaced by LDRs. It's really just a bunch of EQ presets and it interpolates between them as you increase the value." source
8. "I have two of them. Both with the Lead 1 Red board." source

Yek's write-up

USA PRE LD1 RED (TX-4 board)

Firmware release notes: "Based on the Lead 1 Red mode of a Mesa Triaxis preamp with the TX-4 board".

USA SUB BLUES (based on Mesa/Boogie Subway Blues)

Model:

1. single channel

Cab: Mesa 1x10 (Eminence Black Shadow)

Original controls:

• Volume, Bass, Mid, Treble, Reverb. Bright and FAT voicings are available through separate inputs or through a switch

Yek's write-up

VIBRA-KING (based on custom Fender Vibro-King)

Model:

1. Fat switch engaged
2. Fat switch off

Original controls:

• Volume, Treble, Bass, Middle, Fat switch, Tremolo, Reverb

Cab: Fender 3x10

Cliff:

1. "The model is based on the custom version which has higher plate voltages which causes more overdrive on the power tubes."

Yek's write-up

VIBRATO LUX (based on '62/'63 brownface Fender Vibrolux)

Model:

1. Bright channel (turn off Bright for Normal channel)

Cab: Fender 2x10 or 1x12

Original controls (Vibrato channel):

• Volume, Bass, Treble, Vibrato

Cliff:

1. "Early Dire Straits tone is a Vibrolux (Vibrato Lux model). The Vibrato Lux model is based on the same model and year amp used on the eponymous album. There's a cab in there too." source
2. "It's a Vibrolux. That IR is from my personal 1962 Vibrolux. This is the amp used on Dire Straits eponymous album." source
3. "It's a Brownface." source

Yek's write-up

VIBRATO VERB (based on Fender Vibroverb)

Model:

1. old model, ported from the Axe-Fx Ultra

Cab: Fender 1x15 (Jensen C15N, JBL D130, Eminence)

Original controls:

• Volume, Bass, Treble, Bright switch, Reverb, Tremolo

Cliff:

1. The Transformer Matching value for the CS model is based on the output transformer in the actual amp. Legend has it that SRV used a Bassman transformer which would lead to significant overmatching. To replicate this increase Xfrmr Match to around 1.8.

Yek's write-up

VIBRATO VERB AA (based on '64 blackface Fender Vibroverb, AA763)

Model:

1. single model (Cliff's personal amp)

See above

VIBRATO VERB AB (based on Fender Vibroverb, AB763)

Model:

1. single model

See above

VIBRATO VERB CUSTOM (based on Fender Vibroverb Custom Reissue)

Model:

1. single model

See above

Cliff:

1. "The Transformer Matching value for the CS model is based on the output transformer in the actual amp. Legend has it that SRV used a Bassman transformer which would lead to significant overmatching. To replicate this increase Xfrmr Match to around 1.8."

WRECKER EXPRESS (based on Trainwreck Express)

Model:

1. Wrecker Express: bright switch on original amp in center or top position
2. Wrecker Express Bright: bright switch on original amp in bottom position

Original controls:

• Volume, Bas, Mid, Treble, Presence, Bright switch (center: off, top: clarity and sparkle, bottom: jangly highs)

Cliff:

1. "The secret to a Trainwreck is the output transformer. The impedance ratio is about twice that of other amps. I.e. typical 50W Marshall has a primary impedance of about 3200 ohms. A Trainwreck is about 6500 ohms. The causes the power tubes to clip much sooner." source
2. "Real Trainwrecks are very spitty amps. This is because the last stage heavily overdrives the phase inverter. 7.02 is faithful to the actual amps whereas previous firmwares were more idealized. As was indicated in the release notes you can dial out this behavior by decreasing the PI Bias Shift. If you set it to zero it will be like 6.xx." source
3. Cliff's Tech Note: "A real Trainwreck Express is a fizzy, spitty amp. Some people like this. The same people who like fuzz pedals and that quasi-half-wave rectified sound. Personally I like more clarity. The reason the Express is like this is primarily due to the last triode stage before the phase inverter (PI). This stage is biased very cold and drives the PI very hard due to the lack of any limiting resistor (grid stopper) between the triode and PI. The lack of a grid stopper resistor and large coupling capacitor create significant bias excursion (blocking distortion). It appears the designer attempted to minimize the bias excursion by biasing the triode cold which limits its positive excursion and therefore limits the PI grid conduction. Despite the cold bias point the PI grid is still heavily overdriven resulting in massive blocking distortion. The Axe-Fx allows you to reduce the amount of block distortion via the PI Bias Excursion parameter. Simply turn this down and the spittiness will go away. You can then also rebias the triode via the Preamp Bias parameter. Values closer to zero result in a more symmetric waveform." (...) "Turn PI Bias Excursion to 0. Set Preamp Bias to -0.15 or so. (source)"
4. "The reason they clean up when you back off the volume is because the OT is so overmatched. It's about twice the optimum value." source
5. "The real amp is a nasty thing. Very spitty as one would expect given the lack of a grid stopper resistor between the last triode stage and the PI." source

Yek's write-up

WRECKER LIVERPOOL (based on Trainwreck Liverpool)

Model:

1. single channel

Original controls:

• Volume, Bas, Mid, Treble, Presence, Bright switch

Cliff:

1. "The secret to a Trainwreck is the output transformer. The impedance ratio is about twice that of other amps. I.e. typical 50W Marshall has a primary impedance of about 3200 ohms. A Trainwreck is about 6500 ohms. The causes the power tubes to clip much sooner." source
2. "Just because a power amp is "Class A" doesn't mean it can't have negative feedback. True that the majority do not but this particular amp has quite a bit of NF." source
3. "Uses a Vox-style phase inverter." source
4. "Real Trainwrecks are very spitty amps. This is because the last stage heavily overdrives the phase inverter. 7.02 is faithful to the actual amps whereas previous firmwares were more idealized. As was indicated in the release notes you can dial out this behavior by decreasing the PI Bias Shift. If you set it to zero it will be like 6.xx." source
5. Cliff's Tech Note: "A real Trainwreck Express is a fizzy, spitty amp. Some people like this. The same people who like fuzz pedals and that quasi-half-wave rectified sound. Personally I like more clarity. The reason the Express is like this is primarily due to the last triode stage before the phase inverter (PI). This stage is biased very cold and drives the PI very hard due to the lack of any limiting resistor (grid stopper) between the triode and PI. The lack of a grid stopper resistor and large coupling capacitor create significant bias excursion (blocking distortion). It appears the designer attempted to minimize the bias excursion by biasing the triode cold which limits its positive excursion and therefore limits the PI grid conduction. Despite the cold bias point the PI grid is still heavily overdriven resulting in massive blocking distortion. The Axe-Fx allows you to reduce the amount of block distortion via the PI Bias Excursion parameter. Simply turn this down and the spittiness will go away. You can then also rebias the triode via the Preamp Bias parameter. Values closer to zero result in a more symmetric waveform." (...) "Turn PI Bias Excursion to 0. Set Preamp Bias to -0.15 or so. (source)"
6. (about the Tech Note) "Applies to the Liverpool because the preamp is almost identical to the Express." source
7. "The reason they clean up when you back off the volume is because the OT is so overmatched. It's about twice the optimum value." source

Yek's write-up

WRECKER ROCKET (based on Trainwreck Rocket)

Model:

1. single channel

Original controls:

• Volume, Treble, Bass, Cut

Cliff:

1. "The secret to a Trainwreck is the output transformer. The impedance ratio is about twice that of other amps. I.e. typical 50W Marshall has a primary impedance of about 3200 ohms. A Trainwreck is about 6500 ohms. The causes the power tubes to clip much sooner." source
2. "The Rocket has a different preamp (than the Express) with the tone stack before the PI. This reduces the signal level substantially and lessens the amount of blocking distortion." source
3. "The reason they clean up when you back off the volume is because the OT is so overmatched. It's about twice the optimum value." source

Yek's write-up