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Amp and Cab modeling for beginners

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Virtual preamps

  • The Axe-Fx II and AX8 are guitar preamps. They model more than hundred real amps such as heads, combos and racked preamps. You can also use its many other effects, use it to reamp a dry signal, create tone matches of real amps and recordings (Axe-Fx only), create impulse responses (Axe-Fx only), use it for mastering (Axe-Fx only), etc.

Virtual power amps

  • The Axe-Fx II and AX8 have built-in power amp simulation which means that you can listen to the sounds of the modeled amps through headphones and neutral amplifiers, and connect the device to a mixer or record it without needing a separate power amp. You can switch off power amp simulation in Hardware menu: Global.

Using a real power amp

  • To amplify the Axe-Fx II or AX8 through a speaker, you need a power amp. Either a standalone tube power amp designed for guitar, a head or combo (through its effects loop), or a so-called neutral power amp. You can also use studio monitors and monitor wedges with built-in amplifiers (aka "active" or "powered" monitors).

Playing through a guitar speaker

  • You can use the Axe-Fx II and AX8 with a traditional guitar speaker, in combination with a power amp. This will give you the familiar amp-in-the-room tone. It does limit their possibilities, because any sound you will create will go through that speaker and therefore will be colored by it.

Using FRFR amplification

  • You can opt for FRFR amplification sound reproduction. This requires a FRFR speaker and an external or built-in neutral (power) amp. Studio monitors are FRFR, as well as some wedges / cabs.

Cabinet modeling and IRs

Listening through FRFR amplification

  • It's very important to realize that when you're using FRFR with cabinet modeling, you'll be listening to the sound of a mic'd speaker, as opposed to an amp-in-the-room. A cab model always represents the tone of a speaker that as captured using one or more microphones, mostly positioned very close to the speaker. That's totally different from listening to a guitar speaker at some distance. FRFR has more lows, more highs and has the coloring of the used microphone baked in. It takes a while to get accustomed to FRFR tone, but it's the tone the audience hears, through the FOH system or when listening to recorded music. More information.

Being heard in the mix

  • Important in general, but especially when playing through FRFR amplification: the Fletcher-Munson curve. This is the scientific name for the fact that human ears perceive sound at low volume levels differently than at higher levels. At low volume level people often turn up treble and bass. The Loudness switch on older home stereo systems does just that. At higher volume levels those controls need to be turned down again because, in a live environment, tones with too much treble and bass are prone to get lost in the mix (the guitar will compete with cymbals and bass guitar and will loose). Even turning up the volume level often won't help. Remember that the guitar is a "mid frequency" instrument. So: always dial in your live guitar tones at gig level.

Solving clipping

  • Setting levels: be aware that input clipping is something totally different than output clipping.
  • It's okay for the LED to "tickle" the red. If it happens all the time, decrease Input Level in Hardware menu: I/O. Be aware that this is not a real input level control, the control controls the signal-to-noise ratio only and does NOT affect signal level or gain or tone (except at the lowest and highest settings).
  • The output clipping LED light indicates that the signal level in the effects chain is too hot. Adjusting Input Level does NOT solve this. Decrease the level somewhere in the chain, preferably using Level in the Amp block.

Creating and editing sounds

  • Read the Owner's Manual for editing instructions. The Axe-Fx manual includes a 60-Second Edit Guide and an overview of shortcuts.


  • Axe-Edit and AX8-Edit — load and save presets from/to disk, edit sounds, rearrange presets and user cabs.
  • Fractal-Bot — backup or restore your device, load and save presets and user cabs, upgrade the firmware.
  • Cab-Lab — mix IRs, convert IRs, create an IR of your guitar cabinet (IR Capture).
  • Note: you need to install a driver first before you can connect the Axe-Fx to a computer. Download it here.

Questions or issues?