Axe-Fx II (legacy)

Axe-Fx II hardware in the owner's manual

• Axe-Fx II: 2.1 The Front Panel; 2.2 The Rear Panel; 3.2 The PEDAL Jack; 3.4.11 Axe-Fx II- One Possible Big Rig; 4.3.1 Quick Control ABCD; 4.4 X/Y Switching; 8 Global Parameters; 9 Input/Output Parameters; 9.6 X/Y Quick-Jump Assign; 10 Utilities; 11 Tuner; 12 Tempo; 16.12 Humbuster Technology; 17 Specifications; Input/Output Hardware and Parameters Guide.

Axe-Fx II manufacturing details

• Cliff: "Our current production model is to source the chassis from China. The PCAs are made in USA and final assembly and QC are done in USA. The MFC-101 is fully made in China. The EV-1s are fully made in China except for the pots which are made in USA as nothing in China or Japan met our lifespan requirement (1 million rotations minimum)." source
• Manufacturing information.

Axe-Fx II hardware parts, weight, dimensions

• Cliff's comments about parts:
  1. "The Axe-Fx II is a no-compromise product and that is reflected in the price. Most, if not all, manufacturers use, for example, TL074 op-amps for the analog I/O. Those are inexpensive, quad, FET input op-amps with okay performance. They cost about a ten cents each. We use high-end Analog Devices products that cost about a dollar for a dual. These are reference-grade amps. We use film capacitors where possible in critical signal path locations. Again, much more expensive but reference-grade performance. The A/D and D/A converters are reference-grade. Even the circuit board has gold-plated pads as compared to tin." source
  2. "We use the flagship Cirrus converters along with Analog Devices "Butler" op-amps. Film caps where possible. All I/O to the converters is balanced to provide optimum SNR and distortion performance. One of our op-amps costs ten times what is commonly found in other products." source
  3. "I'd be willing to put the converters and circuitry up against the best names in the industry." source
  4. "It uses better converters than a Metric Halo. That said, many converters color the sound and people interpret that as "better". The Axe-Fx DACs are designed to be completely neutral." source
  5. "The Axe-Fx II, FX-8 and AX-8 use heavy-duty steel chassis, audiophile-grade op-amps, "flagship" converters, full-differential analog paths, PPS (poly-phenylene sulfide) film caps, ENIG (electroless nickel, immersion gold) circuit boards, etc." source
  6. "One of the Axe-Fx's DSPs is more powerful than both DSPs combined in the Helix. Our tests show that the TigerSHARC DSP used in the Axe-Fx is over twice as fast as the DSP used in the Helix clock-for-clock . Now add that our DSP is clocked 50% higher the net power is about three times greater. So a single TigerSHARC is about 50% faster than both DSPs combined on the Helix. Yes, if we decided to use both DSPs for effects then you would be able to run more effects. 99% of our customers buy the unit for amp modeling so it doesn't make sense to invest the time and resources to making this possible. Our algorithms are studio-quality and use more processing power than competing products. We've always been about quality over quantity. For example, our variable delay algorithm (chorus, flanger, etc.) uses poly-phase interpolation. EVERY competing product I have tested uses simple linear interpolation (or occasionally polynomial interpolation) which is far less computationally intensive but doesn't sound as good. This is demonstrable and measurable." source
  7. "We do not use "China parts". Our Contract Manufacturer (who is located in the USA) buys the parts we specify from domestic distributors. Typically Arrow, Avnet, Mouser, Digi-Key, etc. Many of those parts ARE made in China as well as Mexico, Taiwan, Vietnam, etc. There are virtually zero electronic component factories in the US. All the major electronic manufacturers have set up factories outside the US because labor is far cheaper and tax laws are more favorable. We also specify premium grade parts unlike most manufacturers in this market space. I challenge anyone to compare the components used in our products to the components used by other manufacturers. We always use reference-grade converters, op-amps, film caps, etc. because it matters and you can hear it. We don't choose the lowest bidder, we choose the best quality. Our sheet metal and related chassis components are sourced from China as there are really no good sources of sheet metal fabrication left in the US. It's also the most labor intensive part of production but has no bearing on the sound quality." source
  8. "The input circuit of Fractal products mimics the input of a tube amp very accurately: (see graph)". source
• Power supply:
  1. Power supply specifications
  2. Cliff: "The power supply is quite over-spec'd. The unit only requires about 25W but I spec'd a 40W supply to ensure longevity under difficult operating conditions." source
• Dimensions: 17" x 12.93" x 2.87" (433.4mm x 328.5mm x 73mm).
• Weight: 10lbs (4.5 kg). source
• Fan:
  1. Cliff: "The fan was changed to 80mm quite some time ago. The XL and XL+ have the fan mounted to the motherboard which eliminates the coupling into the cover which further reduces noise. The XL and XL+ are nearly silent." source
• Battery:
  1. The Axe-Fx II Mark I and II use a battery, expected to last over 10 years. When the battery dies, presets will get corrupt and disappear. Install a fresh CR2450 Lithium battery.
  2. Cliff: "Replacing the battery does not void the warranty". source
  3. Cliff: "The XL and XL+ have a battery. It's a CR2032 IIRC." source
• Encoder wheel:
  1. If your encoder (value wheel) behaves erratically, it may be broken.
  2. "The XL and the XL+ both use optical encoders. The Mark I and Mark II have mechanical encoders." source
• Accidentally plugging USB into CAT5 connector:
  1. Cliff: "Mark II, XL and XL+ models have a PTC fuse on the jack to protect against this." source
• LCD display:
  1. 160x80 Brilliant Green.
  2. If there's a display problem, check the ribbon cable inside the Axe-Fx.
  3. Cliff: "An occasional flicker when hooked up to USB is not unusual. This is due to the screen redraw being interrupted by the USB thread." source
  4. Cliff: "Display flickering on the tuner is normal. Some do it more than other. It's just the nature of the display. The display uses a ping-pong buffer. One page is updated while the other is displayed. Then the pages are switched. Some flickering can occur during the page switch. The reason it is noticeable more on the tuner is that the display is updated more frequently." source
  5. The Axe-Fx II XL+ has an updated LCD display and display controller.
• Output level knobs:
  1. Cliff: "We test the output to be flat within +/- 1 dB over the range of the knob. In fact I'd be surprised if there were any measurable variation at all." source

Axe-Fx II hardware test

• Cliff: "One way you can test the I/O is to use the synth block. Set the oscillator to pink noise and route it to the various outputs. Be sure to set the filter to 20 kHz (default is 10). Check the spectrum with your analyzer plug-in. It should be flat. You can then route the output of the synth to Output 2 and then jump Output 2 to the Inputs and route the inputs to Output 1 to make sure the inputs are working properly. Route it directly to the Output to test Output 1. Route it only to the FX Loop block to test Output 2. Then run a short cable from Output 2 to the front panel Input to test the input. Run a line of shunts from the input to the output." source

Axe-Fx II power cycling

• Use the front panel knob to switch the unit on or off. Or just disconnect the power as often as you want, it doesn't hurt the Axe-Fx II. Remember that presets need to be saved first. All other changes are saved automatically. More information
• Possible issues when cycling power:
  1. If you use a power conditioner, try powering up the Axe-Fx II AFTER switching on the power conditioner.
  2. If a corrupt preset causes the Axe-Fx II to freeze during startup, hold Recall while powering up. This make the Axe-Fx II skip that preset and start with an empty one. If this doesn't help, verify that the preset doesn't link to a corrupt user cab.
  3. Cliff about low voltage: "Modelers are like synths in that regard. They will sound the same but if the voltage gets too low they may start acting weird, shutting down, etc. Modelers are really just specialized computers. If the voltage gets too low they can malfunction." source
  4. If the Axe-Fx won't boot anymore, contact Fractal Audio Support. You may need an emergency EPROM which you can use to boot the Axe-Fx II (Mark I or II). The Axe-Fx II XL has a built-in emergency EPROM: hold down Page Left and Page Right while cycling power.
  5. To avoid the "pop" when powering up, start the Axe-Fx II before the amplifier. And vice versa when shutting things down. The XL+ surpresses the "pop" at startup.
• About power conditioners:
  1. http://forum.fractalaudio.com/axe-fx-ii-discussion/70810-why-use-power-conditioner.html
  2. http://forum.fractalaudio.com/lounge/72318-power-conditioners-snake-oil.html
• Cliff: "The power supply has an on-board fuse." source

Axe-Fx II ABCD Quick-Control knobs

• The ABCD knobs on the front panel work as modifiers in the Control > Manual screen.
• Knob A is used to switch scenes when in the Recall screen or Layout menu.
• The ABCD knobs can be used as tone and gain controls (Drive, Bass, Middle, Treble) in the AMP block's first page. An easy way to get quick acces to these, is to assign "X" on the front to the AMP block in the I/O menu. A quick press on X will then take you to the page with tone controls and you can use ABCD for quick editing.
• The ABCD knobs on the AMP block's Type page can be used to control certain parameters. However, when modifiers are attached to those parameters, the ABCD knobs will control the modifers. source

Axe-Fx I flutter noise when adjusting levels

• Cliff: "That's normal. The output "pot" is actually a ladder of discrete resistors that is remotely controlled by the knob on the front panel. Other products simply reduce the digital signal going into the D/A converter but this is sub-optimum as you reduce your dynamic range when doing this. The Axe-Fx II strives to keep the signal into the D/A as high as possible for optimum dynamic range and then controls the output level using a programmable output gain. The downside of this approach is that you will hear a small noise when the output switches between the resistors in the ladder." source

Axe-Fx II frequency response and aliasing

• The frequency response of the Axe-Fx is flat. Frequency response in Wikipedia
• Aliasing tests and discussion

Axe-Fx II latency

• Latency is the delay between what you do or play and what you hear. The Axe-Fx II's latency is so low that it is equivalent to standing just a few feet away from an amp.
• Cliff's comments:
  • "Should be around 2ms. If not using the amp block it's around 1.3 ms."
  • "The Axe-Fx II has the same latency as the old Axe-Fx. The amp block in the II, however, has an additional 0.3 ms latency due to shuffling the data back and forth between the master and slave DSPs." source

Axe-Fx II Bypass mode

• When the Axe-Fx II is put into Bypass, the signal is routed directly to the D/A converters after A/D conversion. Inbetween there's no signal processing. It's like a row of just shunts on the grid. There's still signal but it is less loud and sounds "dry". Bypass mode is indicated on-screen. So if your sound suddenly is gone, there's no amp distortion to be heard and no effects, always check if the Bypass button hasn't been pressed by accident.
• There's a 6dB volume level difference between Bypass and non-Bypass mode. This is by design.
• For an explanation of the different Bypass states of effect blocks, see Effect Level, Mix and Bypass.
• The MIDI CC for putting the Axe-Fx into Bypass mode is CC 13.
• If pressing the Eff.Bypass button on the front panel doesn't bypass an effect block , its Bypass parameter probably is attached to a modifier. In that case the modifier has total control over the block’s bypass switch and Eff.Bypass will not work. Utilize the modifier or remove it.

Axe-Fx II racking

• The Axe-Fx II is a 19” 2U device. It can be mounted in a rack or rackbag. If necessary combined with a racked power amp, a power conditioner, a custom front panel, a controller such as the RAC12, etcetera. Rear rack rails are not required or supported. It's about two inches deeper than the Standard and Ultra.
• If you are looking for a custom rack panel to bring the rear inputs and outputs to the front, try Vafam or BTPA.
• The rack ears at the front are removable if you need the space.
• You can put the rack or bag on a amp stand. Example
• Cliff: "From the rack ears to the back of the chassis is only 13". You should allot a couple inches for plugs and cables though." source

Axe-Fx II Mark II

• The original model has been replaced with a Mark II model in October 2012. The main change is the addition of an EtherCon jack, replacing the standard RJ45 port for connecting an MFC-101. This is in line with the MFC-101 Mark II version. EtherCon offers built-in strain protection to guard against damage from CAT5 cable pulls or jolts. It's backward compatible with standard Ethernet cables, however EtherCon is recommended for harsh environments. Another change is that Mark II models are protected against inserting the ethernet cable into the USB port. source
• Cliff's comments:
  • "The connectors are backward and forward compatible. The problem was that people were breaking the connectors, especially on the MFC. So we changed them to more durable connectors." source
  • "The only difference between MK I and MK II are some vents in the chassis, larger fan and an Ethercon jack instead of an Ethernet jack. Otherwise the hardware is identical. I can see the XL possibly sounding a bit better and the XL+ sounding even better than the XL but there should be negligible difference between a Mark I and a Mark II." source
• The Mark II model has been discontinued.

Axe-Fx II XL

• Announced in January 2014 and available from March 2014.
• The Axe-Fx II XL has the same DSP and amp modeling capabilities as the Axe-Fx II Mark II, but offers expanded memory, new I/O ports, and other upgrades detailed below:
  • Built-in FASLINK port for connection to MFC-101 Mark III over conventional XLR cables.
  • Dedicated MIDI IN, OUT, and THRU jacks (vs. shared OUT/THRU in the Mark II).
  • Two onboard PEDAL jacks (vs. one in the Mark II).
  • Primary VALUE entry via (powered) optical encoder with a lifespan of 1,000,000+ rotations.
  • “Secret Sauce III” instrument input features an even lower noise floor.
  • 128 Mb of non-volatile Super-FLASH memory allows for storage of up to 512 presets (increased in later firmware) and 512 user cabinets (increased in later firmware) with copious reserves for future expansion.
  • Double-capacity preset size allows for expanded functionality including X/Y switching on more blocks and more instances of effects.
  • Built-in backup firmware allows recovery in the event of complications during update.
  • Backward compatibility with Axe-Fx II Mark I/II presets via Axe-Edit software.
• Cliff source:
  • "The primary impetus for the XL was the FASLINK port. Since I had to develop a new mainboard to support this I figured why not put in some of the other requests we get from the power users.
  • The additional memory is FLASH which is EPROM not RAM. This will not increase the looper time as the amount of RAM has not changed.
  • The type of FLASH memory is "Super-FLASH" which is an expensive, high-reliability memory. It can be erased hundreds of thousands of times without wearout or slowdown. This prevents the need to wear-level the memory and the dreaded "Tuning Memory" stuff.
  • There is no longer any SRAM for preset storage. All presets are stored in FLASH.
  • There is still a small SRAM for storage of system information that requires a battery. You can still back your system up to FLASH. If the battery dies you won't lose your presets and hopefully you've backed up your system.
  • There is enough FLASH memory to store 1024 presets and 1024 user cabs but I'm reserving half the memory for future upgrades.
  • The "Special Sauce III" uses a combination of things to get a lower noise floor. One of these things is new, premium Burr-Brown op-amps in the signal path which have extremely low noise and distortion (and are very expensive). As always I don't design stuff to be cheap, I design it to be good.
  • The optical encoder requires power and therefore can not be retrofitted into a Mark I/II. Also the shaft and bushing size are different so it doesn't fit anyways.
  • Ultra-Res is not specific to the XL.
  • All algorithms will be identical between the Mark I/II and XL. They all share the same code base. Any enhancements/improvements will benefit all models except when aforementioned features are not available."
• Cliff: "The MFC-101 stores 384 presets. The Axe-Fx II Mark I/II also store 384 presets. The XL stores 512 presets (firmware 15.04: 768) and maybe someday 1024. Many MIDI controllers only store 128 presets. There is no correlation between the number of presets on a MIDI controller and the device being controlled. This is not a bug, mistake or deception." source
• The XL can import presets from the Axe-Fx II/Mk II but not vice versa.
• The Axe-Fx II XL has 159 stock cabs.
• The XL model has been discontinued.

Axe-Fx II XL+

• Available from March 2015.
• Minor revision of the XL: other LCD display/controller, and slightly lower noise.
• Announcing the Axe-Fx II XL Plus
• Cliff's comments:
  • "The XL+ has semi-automatic pop suppression. It's automatic on power on. If you turn down the Output Level knob before turning the power off it will activate the power off suppression. Even if you don't the pop is somewhat suppressed as the there are output clamps that activate when the voltage drops below a certain threshold." source
  • "The XL+ is slightly quieter. It has some minor improvements to the front end electronics. It's not a difference we feel is worth crowing about as the XL is already very quiet. The data bus is also slightly improved which yields a small reduction in base CPU usage. And finally there is power up/down pop protection on the outputs. We could've made a big deal about these things but they're minor and not significant improvements over the previous models. They're just little tweaks. We had to redesign the board for the new LCD so we took the opportunity to tweak a few things." source
  • "Pop protection on power off requires turning the Level knob(s) all the way down. If you don't you'll still get a little pop but not enough to damage speakers." source

Axe-Fx II model differences

• Mark II:
  • Addition of an EtherCon jack (replacing the standard RJ45 port for connecting an MFC-101).
  • Protection against inserting the ethernet cable into the USB port.
  • Some vents in the chassis.
  • Larger fan.
• XL:
  • Built-in FASLINK port for connection to MFC-101 Mark III over conventional XLR cables.
  • Dedicated MIDI IN, OUT, and THRU jacks (vs. shared OUT/THRU in the Mark II).
  • Two onboard PEDAL jacks (vs. one in the Mark II).
  • Primary VALUE entry via (powered) optical encoder with a lifespan of 1,000,000+ rotations.
  • “Secret Sauce III” instrument input features an even lower noise floor. The "Special Sauce III" uses a combination of things to get a lower noise floor. One of these things is new, premium Burr-Brown op-amps in the signal path which have extremely low noise and distortion (and are very expensive).
  • 128 Mb of non-volatile Super-FLASH memory allows for storage of up to 512 presets (increased in later firmware) and 512 user cabinets (increased in later firmware) with copious reserves for future expansion.
  • Double-capacity preset size allows for expanded functionality including X/Y switching on more blocks and more instances of effects.
  • Built-in backup firmware allows recovery in the event of complications during update.
  • Backward compatibility with Axe-Fx II Mark I/II presets via Axe-Edit software.
  • No SRAM for preset storage. All presets are stored in FLASH.
  • 159 stock cabs.
• XL+:
  • Other LCD display/controller.
  • "Semi-automatic pop suppression. It's automatic on power on. If you turn down the Output Level knob before turning the power off it will activate the power off suppression. Even if you don't the pop is somewhat suppressed as the there are output clamps that activate when the voltage drops below a certain threshold. Pop protection on power off requires turning the Level knob(s) all the way down. If you don't you'll still get a little pop but not enough to damage speakers."
  • "The XL+ is slightly quieter. It has some minor improvements to the front end electronics. It's not a difference we feel is worth crowing about as the XL is already very quiet. The data bus is also slightly improved which yields a small reduction in base CPU usage. And finally there is power up/down pop protection on the outputs. We could've made a big deal about these things but they're minor and not significant improvements over the previous models. They're just little tweaks. We had to redesign the board for the new LCD so we took the opportunity to tweak a few things."
  • "The XL+ uses slightly less CPU because of a more efficient video path." source

Axe-Fx II: (un)balanced audio

• See Balanced and unbalanced audio.

Axe-Fx II: FASLINK

• See FASLINK communications.

Axe-Fx II: Humbuster

• See Humbuster cables.

Axe-Fx II original circuit board