chip utilisé pour le crunch ?

LEDs typically have a forward voltage drop of 1.5V or higher. Si diodes are typically 0.7V.

The gain of a typical TS clipping stage is still substantial, typically around 117 at maximum, so given an input signal of 100mV p-p, the amp will try to make an output of 11.7V p-p, which is impossible with a 9V battery. However, the diodes will limit the output to their forward voltage (in either direction), which for Silicon means a max output voltage of 1.4V p-p. Obviously the op-amp is trying to generate a larger voltage, so the excess is "clipped" by the diode, and you hear the result as distortion.

For LEDs, they will allow a max signal of perhaps 3V p-p, which is quite a lot more. Many guitar signals are less than the 100mV example I gave above, so often you will hear no clipping at all. However, the output level will be higher because a 3V signal is larger than a 1.4V signal. You would hear this as louder but cleaner.

The gain is the same in both situations, which is a good example of how terms come to mean different things in different contexts.

Ok, donc on tourne bien autour d'une TS 808 utilisant des leds plutôt que des diodes.

Je vois que les LEDs ont des voltages différents (et du coup je comprends pourquoi c'est plutôt des diodes utilisés dans les pédales TS et pourquoi il y a peu de pédales en LEDs)