The Electro-Harmonix Big Muff has had many versions during its lifetime. The unit we have here is the V4 one which is associated with Billy Corgan of the Smashing Pumpkins. What most people do not know is, that this pedal works super well with bass guitars too. The unit we demoed uses the EH-1322 board and is all stock. As to sound, try it out for yourself with the bass of your choice using the TonePedia player. The EHX Big Muff Pi V4 was in production for approx two years, so it is relatively hard to find.