From Axe-Fx II Wiki
The information on this page supplements the official manuals.
- Amplifying a signal with cabinet modeling requires a specific amp/speaker solution: a Full Range Flat Response (FRFR) monitor. This can be a pair of powered studio monitors, a powered FR cab, or a FR wedge/cab with a built-in or separate neutral-sounding power amplifier. Or the FOH mixing console, when there is a PA sound system present (aka 'going direct'). FOH means Front Of House, to distinguish it from a monitor mixer on stage. The FRFR principle: what goes in goes out, with as little tone coloring as possible. Tone shaping is left to the input device, in this case: the Axe-Fx II or AX8. FR(FR) monitors can be active/powered (including a power amplifier) or passive (just a cabinet) and often consist of a speaker and a tweeter, separate or coaxical. FR advantages are portability, no tone coloring, reduced stage volume, consistent tone at all volume levels and venues, ability to work with cab modeling, ability to produce synth and acoustic tones.
- FR in Wikipedia.
- Article in Music Radar.
- The Axe-FX II and AX8 provide a broad frequency range. Because of this it can be used for bass, acoustic instruments, guitars etc. When using a traditional guitar cabinet you won't notice the broad frequency spectrum because the traditional speaker filters the tone. FR(FR) amplification however passes all frequencies. If this bothers you, there are several ways to handle this (source):
- Put a PEQ at the end of the grid and block low and high frequencies, or use the LoCut and HiCut parameters in the Cab block to achieve similar results. Try low-cutting (= high-passing) at around 80-150 Hz and high-cutting (= low-passing) at around 6-10 kHz.
- Put the blocking PEQ (see above) before the Amp block instead of after it. This narrows the signal going into the Amp block. It kind of has the same goal but may sound better subjectively.
- Use the Global EQ.
- Use the tone knob on your guitar.
- Cliff's comments:
- "The Axe-Fx is extremely accurate in duplicating the sound of a mic'd amp. Your monitoring thus becomes an essential part of the chain and accuracy is paramount. Many "FRFR" monitors are neither FR nor FR." source
- "Resist the temptation to add bass and treble. The amp designers knew what they were doing (well most of them). If you are applying heavy EQ then you will be disappointed at gig volumes. What sounds midrangey and bland at low volumes will sound great at high volumes. Do some research on Fletcher-Munson to understand this." source
- "You're not going to hear the same thing through FRFR that you heard from guitar cabs. Your audience will hear something very similar but you won't. What you're hearing through FRFR is a mic'd representation of the cabs. It takes some getting used to. You have to start thinking like a producer/engineer rather than a guitar player. If you start trying to dial out what you call "fizz" and "artifacts" you're going to end up with a tone that doesn't cut. It might sound good to you but it won't fit in the mix. That fizz and sizzle is what makes those classic rock tones work. Listen to some isolated tracks of VH and AC/DC and you'll hear a ton of high-end sizzle. In the mix, however, it's not noticeable. If you remove it then the guitar sounds dead." source
- "The sound of an amp in the "far field" is quite different than what you get with close mic'ing. IR's are made using close-mic'ing and therefore sound nothing like listening to a guitar cab at distance from the cone. Your audience does not hear the far field tone, they hear the close mic'd tone as that's what is put through the FOH. It can be quite an adjustment coming from far field amp tone to close mic'd tone. Some people just never adjust. Fortunately the Axe-Fx was designed to give you the best of both worlds. You can use the FX Loop and Output 2 to a power amp and conventional guitar cab while routing the fully processed tone with IR to the FOH. See the manual for full details. Rather than using your amp you can use a lightweight solid-state power amp and any of the new, lightweight guitar cabs that use Neodymium speakers. This gives you the classic far field amp tone for yourself in a lightweight package and the polished sound for the FOH direct from Output 1." source
- "Close-mic'd IRs typically have a lot more high frequencies than what you hear at a distance and off-axis from the speaker." source
- "All speakers "move air", that's the entire point of their design. Guitar speakers are inherently directional at higher frequencies. So when you stand off to the side you hear less highs. If you have two or four speakers the directivity gets even worse. FRFR speakers have less directivity. This combined with IR technology that almost invariably uses samples of a close-mic'd speaker and you end up with a different listening experience. To confuse the issue further many combo amps have an open back which changes the frequency response at the listening position even more. Now, if you connect your Axe-Fx to a power amp and traditional 1x12, 2x12, etc. then you will get "amp in the room" but the "moving air" statement has no basis in fact." source
- "FRFR is just not the same. Traditional head/cab you hear the sound from a bandwidth-restricted speaker at, say, 10 ft. In a typical modeler setup you are hearing what the "mic heard" when the IR was made and that mic was pushed up against the grill cloth. One approach is to use "far field" IRs which are obtained using a measurement mic at a typical listening distance and angle. These are rare. There are a couple stock far-field IRs. They are indicated by (JM) for Jay Mitchell, who created them. Even then it's still not the same because when you are using a traditional setup you move around while playing and the tone changes based on the angle. With a far-field IR the tone doesn't change with angle. When I was gigging I used a power amp and cab behind me and sent the XLR outputs to FOH. More gear to lug but best of both worlds: traditional backline sound, consistent FOH sound." source
- "You're never going to get a full-range monitor to sound like an amp in the room regardless of the IR used. One reason for this is dispersion. A traditional guitar cabinet has a beam pattern that decreases with increasing frequency. This means less high frequencies when listening off-axis. A full-range monitor will have more highs. Now some will argue that if you capture the traditional cab off-axis in the far field then you'll get the same thing but you won't because the monitor is not interacting with the environment in the same way. The traditional cab will send less frequency content to off-axis which is then reflected off the floor, walls and ceiling. The monitor will send more highs off-axis that are reflected. Our hearing relies a LOT on the spatial cues of reflection and the reflections will not be the same. Compound the above with the fact that 99.9% of IRs are near field captures which sound nothing like the far field. I believe trying to get a monitor to do amp in the room is a lesson in futility. If you really want that sound use a traditional guitar cab." source
- "People often talk about applying low cuts and high cuts. This is because the cabinet models used in modelers are almost always (with a couple exceptions) based on near-field samples of guitar cabinets. IOW, the mic is pushed up against the grill cloth. This just happens to be the way that record producers/engineers mic a cabinet in the studio and the way guitar cabs are mic'd on stage. This is done primarily for isolation reasons. The downside of this approach is that the resulting tone will have a lot more lows and highs than when listening to the amp+cab "in the room". What the mic "hears" when pushed up against the grill cloth is not the same thing that we hear standing 10 feet away. The most common technique to deal with this is to simply cut out the lows and highs using blocking filters, e.g. highpass and lowpass filters. Producers routinely do this when mixing as excessive amounts of lows and highs will cause the guitar tracks to get "lost in the mix". Live sound engineers often do the same thing. The Cabinet block has blocking filters built in for just this very reason. You can also use a couple dedicated filter blocks or a parametric EQ block. For now let's use the Cabinet block. My personal settings are Low Cut around 80 Hz and High Cut around 7500 Hz and Filter Slope set to 12 dB/octave but these are just a starting point. Far-field IRs are available but they are rare due to the difficulty in obtaining them. They require a large facility and special techniques making the process impractical in most cases. So, until an abundant source of far-field IRs are available we need to think like a producer/engineer who is dealing with the mic pushed up against the grill cloth. This means shaping the tone with EQ to remove unwanted frequencies." source
FRFR and "midrange-boost" trick
- Getting accustomed to the FR sound may take some time. It is different. You can apply a mid-boost to FR amplification, recreating the "thump" of a traditional speaker cabinet. Put a PEQ at the end of the grid, set a band (set to Peaking when using the first or last band) to 770 hz, Q at 0.35, Gain between 2 and 4 dB. source
Connecting FRFR amplification
- When using FR amplification, you DO NOT NEED to place a microphone in front of the FR monitor. That wouldn't make any sense because the device already provides speaker and mic simulation to the FR monitor. Going direct is the right way to do it. Run a line from Output 1 (OUT1 is prefererred when using long cables, because it is a balanced connection) or Output 2 to the mixing console. Output 1's XLR and 1/4" outputs can be used simultaneously. Or: use the pass-through connection on your FR monitor, if available.
- Always use a LINE INPUT on the mixing desk to avoid clipping the mixer input with the unit's line level output signal. If only a MIC input is available on the desk, turn down the output level on the front panel of the unit to avoid clipping in the mixer, or turn down gain in the Global EQ.
- Tutorial by AxeFxTutorials.
FRFR monitoring and De-Phase
- The Cab block (Axe-Fx II) provides a De-Phase parameter which adds amp-in-the-room characteristics to the FR sound.
FRFR monitoring and tweeter squeal
- Cliff's comments:
- "Tweeter squeal is magnetic feedback from the speaker's tweeter. Move further away from the speakers. This is a phenomenon unique to FRFR solutions." source
- "Magnetic feedback is an issue unique to FRFR amplification. The tweeter creates a magnetic feedback loop with the pickups. The closer you get to the speaker the more feedback until the point it squeals. The only solution is to move away from the speaker or turn down the gain/volume." source
- "The high-pitched feedback is pickup squeal and is caused by electromagnetic feedback from the speaker to your pickups. FRFR tends to exacerbate this since you have a tweeter feeding back high frequencies. A noise gate can help but the best solution is to move away from the speaker." source
FRFR plus a power amp and guitar speaker
- The Axe-Fx II and AX8 let you combine amplification methods, such as sending a signal with cabinet modeling (FRFR) to Output 1, and a signal without cabinet modeling to Output 2 to feed a power amp and guitar speaker.
- One of the factory presets provides a template for sending a signal to FOH (with cabinet simulation) plus a signal to an external power amp and spaker cabinet (without cabinet simulation).
- More information.
- Tutorial by AxeFxTutorials.