Redoptor is a high quality Vintage Tube Distortion emulator.
The popularity of tube distortion units are as a result of their superiority over the solid-state fuzz distortions which are based on transistor clipper circuits.
Tubes produce even and odd harmonics and naturally compress the signal. Transistors produce only odd harmonics and limit the sound.
In ordinary fuzz, when a signal goes over the threshold level it goes through the clipper circuit. As the signal volume falls back below the threshold (as the sound reaches its release stage), the harmonics added by clipping suddenly disappear. If the volume of a signal oscillates above and below the threshold, the clipping harmonics will appear and disappear with the signal level. This sounds unnatural and is unpleasant to listen to.
This does not happen in Redoptor. As the sound source falls in volume in its release phase, the harmonics (which were created by the sound being initially above the clipper threshold), gently disappear with the original sound. This creates a very sonically pleasing distortion.