ZVex '59 Sound

[mordechai]

I was really impressed with the demos I've seen for this new pedal from ZVex.  I'm going to buy one because I just like supporting the work of innovative designers, but I'm curious about what's going on under the hood.  Vex suggested that it is a modified Box of Rock, so I am guessing the topology of the circuit is similarly 3-MOSFET based.  But where is this probably tweaked?  I am assuming the values on the tone stack, but where else?  Input cap? gain resistors of the second and thirds stages?   it does a very nice job emulating the tweed Bassman when overdriven (from what I've seen so far) , so I'm curious to hear your thoughts.

[Plexi]

You're right.
Here's an schematic:
http://www.pedalpcb.com/docs/TweedSound.pdf

Talking with Kennt and comparing schematics, get the conclussion that the differences are:
- R9: 270R, less gain (100R on bor)
- C8: 100nf, more bass (10nf on bor)
- C2 and C4 are smaller