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Amp and cab modeling for beginners

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Virtual preamps and power amps

The Axe-Fx series and AX8 are "virtual" guitar preamps. More than hundred heads, combos and racked preamps have been modeled. These processors also provide power amp simulation. This means that you can listen to the sounds of the modeled amps through headphones, a DAW, a PA system, studio monitors, etc.

They also contain many other effects (list), are able to reamp a recorded dry signal, create Tone Matches of real amps and recordings (Axe-Fx only), capture impulse responses (Axe-Fx only), and more.

Read more about the Amp block

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Playing through a guitar speaker or FRFR amplification

You can use the Axe-Fx and AX8 with a traditional guitar speaker. This will give you the familiar "amp-in-the-room tone". It does limit the possibilities, because any sound you will create will go be colored by guitar speaker, instead of using flexible cabinet modeling with its unlimited possibilities.

To amplify the processor's sound through the guitar speaker, a hardware power amp is required. Either a guitar-oriented power amp, head or combo (this requires disabling power amp modeling in the processor), or a so-called "neutral" power amp (with power amp modeling enabled in the processor).

Alternatively, you can opt for FRFR sound reproduction: Full Range Flat Response. This requires a FRFR speaker and an external or built-in "neutral" (power) amp. Studio monitors are FRFR by nature, as well as some monitor wedges / cabs, and high-quality PA-systems.

FRFR systems and direct recording require speaker cabinet modeling because there's no real cabinet in the routing. The Axe-Fx and AX8 have many built-in cabinet models. They also allow loading additional cabs, known as impulse responses (IRs) or user cabs.

It's important to realize that when you're using an FRFR sound system with cabinet modeling, you'll be listening to the sound of a miked speaker, as opposed to a traditional guitar speaker. An IR / cab model almost always represents the tone of a speaker that was captured using one or more microphones placed very close to the speaker. That's an different sound than that of a guitar speaker at a distance. FRFR has more lows (due to the proximity of the mic to the speaker), more highs and has the characteristics of the microphone baked in. It takes a while to get accustomed to FRFR tone, but it's the same tone the audience hears through the venue's sound system and when listening to recorded music.

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Cutting through the mix

Important in general, but especially when playing through FRFR amplification: 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 levels people often turn up treble and bass. The Loudness switch on older home stereo systems does just that. At higher levels those controls need to be turned down again to prevent harsh and boomy tones and to prevent the guitar from getting lost in the mix (a guitar that competes with cymbals and bass guitar will loose). Even turning up the volume won't help. Remember that the guitar is a "mid frequency" instrument. Always dial in your live guitar tones at gig levels!

Solve clipping

Be aware that input clipping is something totally different than output clipping.

It's okay for the Input LED to "tickle" the red. If it happens all the time, adjust Input Level/Pad in the I/O menu. Be aware that this control is NOT a gain control, it controls the signal-to-noise ratio only and does NOT affect signal level, amp gain or tone.

The Output LED indicates that the signal level in the effects chain is too hot. Adjusting the input level will NOT solve this. Decrease the level somewhere in the chain, preferably using Level in the Amp block.

More about settings levels

Fractal Audio software

  • Axe-Edit / AX8-Edit / FX8-Edit — load and save presets from/to disk, edit sounds, rearrange presets and user cabs and much more.
  • 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 with IR Capture.

Note: you may need to install a driver first before you can connect the device to a computer. Download it here.

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Questions or issues