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Difference between revisions of "Amp and Cab modeling for beginners"

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Revision as of 16:31, 5 March 2018

The information on this page supplements the official manuals.


Virtual preamps

The Axe-Fx series and AX8 are guitar preamps. More than hundred heads, combos and racked preamps have been virtualized.

They also provide many other effects, reamp a dry signal, create tone matches of real amps and recordings (Axe-Fx only), create impulse responses (Axe-Fx only), and more.

Virtual power amps

The Axe-Fx and AX8 have built-in power amp simulation which means that you can listen to the sounds of the modeled amps through headphones, mixers and neutral amplifiers. You can turn it off in the Global menu.

To produce amplified tones, an additional hardware power amp (solid-state or tube) or powered monitor is required.

Play through a guitar speaker

You can use the Axe-Fx 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 the possibilities, because any sound you will create will go through that guitar speaker and therefore will be colored by it, instead of using cabinet modeling with its unlimited possibilities.

To amplify the Axe-Fx or AX8 through a guitar speaker, you need a power amp. Either a guitar-oriented power amp, head or combo (with power amp modeling disabled), or a so-called neutral power amp (with power amp modeling enabled in the AX8 or Axe-Fx).

Use FRFR amplification

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, as well as some monitor wedges and cabs.

An FRFR system and direct recording require speaker cabinet modeling. This means that the sound of a virtual speaker cabinet is added. 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 if you're using an FRFR sound system with cabinet modeling, you'll be listening to the sound of a mic'd speaker, as opposed to a traditional guitar speaker. A cab model almost always represents the tone of a speaker that was captured using one or more microphones, positioned very close to the speaker. That's different from listening to a guitar speaker. 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 venue's sound system or when listening to recorded music.

Cut through the mix

Important in general, but especially when playing through FRFR amplification: Fletcher-Munson curves. 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 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 level often 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 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, amp gain or tone.

The Output LED light indicates that the signal level in the effects chain is too hot. Adjusting Input Level/Pad does NOT solve this. Decrease the level somewhere in the chain, preferably using Level in the Amp block.

Create and edit sounds

Read the manuals for editing instructions.

Fractal Audio software

  • Fractal Audio's software editors — 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 may need to install a driver first before you can connect the Axe-Fx to a computer. Download it here.

Questions or issues