Fulltone Bassdrive Mosfet

And the bass version.  This is based on the guitar version but with the passive changes to match the filters in the bass version.  The diodes seem to have changed often in this, some with symmetrical mosfet/germanium combinations with a 1N34A in both directions and some with asymmetrical as shown here.  Some with more than one 1N4001 (or 4005) or asymmetrical on the silicon side with 2 x 1N4001 and 1 x 1N914.  So I'm just leaving the clipping as per the guitar version, and you can put your favourite combination in there if you choose.

Info about the discontinued original:

Bassists need dirt too! But no one, until now, has given you something that works, with all the full, rich bottom-end that you deserve, damn-it! BTW, many guitarists use and prefer the Bassdrive for Guitar!

The Bass-Drive is a lot like its cousin the Full-Drive2, but voiced with an extra octave of bass coverage... still giving a natural, uncolored FATNESS to your thang.

From just adding a little grind, to replicating a raging SVT, to sounding like Jack Bruce in Cream. (He's got one already!)

THIS WILL DO IT!

Here is another version seen in one schematic and confirmed by John K based on values noted in ones he repaired.  This one based on symmetrical clipping with the mosfets using 2 x 1N4001 in that section.  If you prefer to use the asymmetrical mosfet clipping with a germanium diode shown in the first layout, then just use the V1 layout as a base and change the capacitors to the alternative values mentioned in John's post:

1) 100n input coupling cap is 22n
2) 10p input cap to ground is 51p
3) 51p cap between pins 1 and 2 is 100p
4) 220n at pin 2 is 330n
5) 220n at pin 5 is 68n