Dist OPAMP-21 effect is based on the legendary Tech 21 SansAmp Classic guitar processor from 1989, which emulates various tube amplifiers. The original device was designed as an ordinary pedal and allowed you to plug your guitar directly into the line input, bypassing bulky tube amps. This feature is commonplace now, but at the time it seemed revolutionary.
Like all modern Dist effects OPAMP-21 can work in both stereo and Mid/Side modes. Among the additions is separate equalisation of the signal before (Pre-Drive) and after all processing (Post-Drive). The input trim filters operate at a fixed 24dB per octave and, for creative solutions, allow a very narrow bandwidth to be left for processing. There is also an additional Curve setting that slightly reduces distortion in the low frequency region. The output uses a three-band parametric EQ with frequency and quality control. For additional visual control, the EQ has a spectrogram of the signal and allows you to clearly see the changes being made.
The virtual version of the Dist OPAMP-21 pedal works very well and helps to achieve that authentic colour in the sound. Flexible plug-in settings allow you to use the effect not only with guitar, but also with a wide variety of sources, including synthesised timbres.
