Three software developers currently offer amp-modeling plug-ins for Digidesign's Pro Tools TDM systems. Each has its own approach to the modeling process and provides different parameter controls, resulting in tonal characteristics unique to each. (Two of the three, Bomb Factory SansAmp PSA-1 and McDSP Chrome Tone, also run native. SansAmp PSA-1 also runs under RTAS and AudioSuite, and Chrome Tone under RTAS.)
Bomb Factory SansAmp PSA-1 (Mac/Win, $395) is a software emulation of the Tech-21 SansAmp PSA-1 and functions in much the same way. Overdrive is achieved in two separate stages: the Pre-Amp gain control simulates overdrive in the preamp stage, and the Drive knob controls power-amp distortion. In addition to Low and High tone controls, the output stage features a makeup level control.
All of the control knobs have an indent mark representing unity gain. The SansAmp PSA-1 also sports knobs marked Buzz, Punch, and Crunch, which control the amount of overdrive in the low, mid, and high frequencies respectively (see Fig. A). Different combinations of overdrive can yield a wide variety of sounds — from fat sustain to power shred (see Web Clip 1). The factory presets are useful, and the PSA-1 sounds great on other instruments as well. It uses relatively little DSP power.
Line 6 Amp Farm (Mac/Win, $595) bases its design on emulations of classic guitar amps (see Fig. B). It offers models ranging from vintage Fenders and Marshalls (see Web Clip 2) to modern Soldano and Mesa/Boogie amps. Each of the program's 13 amp heads is an accurate representation of the corresponding hardware version, complete with graphic representations of tone controls and switches specific to the selected make and model.
Amp Farm offers a range of speaker-cabinet simulations based on hardware models such as the Vox AC30 and Fender Deluxe, combined with several mic-placement options. Mixing and matching amp heads and cabinets can achieve a wide variety of tones. Whether used on input or as a mixdown effect, Amp Farm makes it easy to dial-in authentic-sounding guitar-amp tone.
McDSP Chrome Tone (Mac, $495) is a suite of plug-ins providing amp simulations and effects. The amplifier module is extremely flexible, featuring six preset levels of distortion combined with compression, gating, and EQ (see Fig. C). The distortion section has an Amount control coupled with single-band (200 Hz to 2 kHz) Frequency and Drive controls to tune the overdrive tone, followed by an output level control. The compressor offers threshold, response (attack), sustain, and release controls.
In addition to a noise gate, you get a 3-band parametric equalizer for further tone sculpting. The output stage includes a spring reverb, a level control, and four speaker simulations.
Chrome Tone's amp module is formidable as a standalone simulator, but it can also run in Stack mode with other included effects such as wah (see Web Clip 3), tremolo, tape echo, and chorus. The depth and modulation of these effects can be triggered by a range of input types (sidechain-audio input, MIDI notes, and so on), making the application very flexible and musical.
Chrome Tone currently runs only on Mac Pro Tools systems, but McDSP says that a Windows version should be available by the time you read this. In addition, a version called Chrome Tone Amp is available as a plug-in for the VS8F-3 plug-in expansion board for Roland VS recorders.