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Amp and Cab modeling for beginners

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Preamp and power amp

Amp block.PNG

Most traditional guitar amplifiers consist of a preamp and a power amp. The preamp is responsible for tone and gain, the power amp makes things loud (real amplification) and may add some distortion and character of its own.

Fractal Audio's amp modelers provide "virtual" equivalents of these preamps and power amps, combined in Amp models. Many heads, combos and racked preamps have been modeled by FAS.

The processors also provide many other effects. And depending on the processor, they can "reamp" a recorded dry signal, create Tone Matches of real amps and recordings, capture Impulse Responses, and more.

More about the Amp block...

Amplification through traditional guitar speaker or Full Range Flat Response (FRFR)

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An amp (real or virtual) needs a speaker (real or virtual) to sound good. Amplification is required to make things loud. Usually this means using either a traditional guitar cab with a power amp, or a so-called FRFR monitor / cab.

  • Traditional guitar cab and power amp

A traditional guitar speaker will give you the familiar, fairly easy to set up, "amp/cab in the room tone". This does limit possibilities, because any sound you will create will be colored by that particular guitar speaker.

When using a traditional cabinet, the preset shouldn't use a Cabinet model. If it does, disable it or disable Cabinet Modeling in the processor's Setup menu.

A hardware power amp is required to provide a loud signal to the speaker. This can be a guitar-oriented power amp, head or combo, which will add its own coloring to the sound and decrease the possible tonal variations. This usually sounds best with Power Amp Modeling disabled in the processor's setup menus.

More popular is a so-called "neutral" power amp. This relies on the virtual power amp of the modeler, so keep Power Amp Modeling enabled in the Setup menu.

More information...

  • FRFR

Alternatively, you can use FRFR sound reproduction and amplification: 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 are some monitor wedges and cabs, high-quality PA-systems, and headphones.

FRFR systems (including direct recording) require Cabinet Modeling because the signal doesn't go through a traditional guitar cab. Fractal Audio's amp modelers provide many built-in cabinet models. They also allow loading external cabs, known as Impulse Responses (IRs).

Important: when using an FRFR sound system with cabinet modeling, you're listening to the sound of a miked speaker. That's a different sound than that of a guitar speaker cabinet. A virtual cab (almost always) represents the sound of a speaker that was captured using one or more microphones placed very close to the speaker (referred to as "nearfield" or "close-miking"). The sound of a guitar speaker at a certain distance is referred to as "far-field". Because of the close proximity of the recording mic to the speaker, the FRFR sound has more highs and lows, and has the characteristics of the microphone baked in. It can take a while to get accustomed to the FRFR sound, but just realize it's the same tone you hear at a concert or when listening to recorded music.

More information...

Cutting through the mix

Many players who start using a digital modeler and take it to rehearsals and gigs, using FRFR amplification, find it difficult to cut through the mix. Turning up the volume doesn't solve this. This is caused by two things:

Input and output clipping


Clipping means that a signal exceeds the limits. While analog clipping can sound pleasing, digital clipping sounds horrible, something that you'll want to avoid.

Clipping can occur at various stages in the device.

  • Input clipping

Input clipping means that the incoming signal (guitar > processor) is too hot.

Real input clipping doesn't happen in Fractal Audio's Devi ces, because a soft limiter kicks in before that. Still, you'll want to optimize the input signal, using the Input LED for this.

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

  • Output clipping

The Output LED indicates that the signal level in the effects chain is too hot for the digital-to-analog converter at the end. Adjusting the Input Level will not solve this. Decrease the digital level somewhere in the chain, preferably using Level in the Amp block, or in the Output block.

More about levels...

Parameter paralysis

The sheer number of parameters and possibilities in Fractal Audio's processors can easily dazzle and confuse users. Sometimes it's handy to be able to fall back on a reference tone.

The Band-Commander (clean tone) and Friedman BE (dirty tone) amp models, both at completely default settings, provide great baseline tones. Combine with cab model Legacy 103 at default settings. Listen with headphones or through studio monitors.


Start here:

Many more tutorials are available from various sources, such as Leon Todd's YouTube channel.

Also, always read the Owner's Manual and don't overlook the FAQ.