I ran across an easy mod using a pair of diodes on the outer lugs of a gain pot at David Barber's website. http://www.barberelectronics.com/compression.htm It's called his vintage compression mod.

Should this work the same way on any gain/drive pot? Anyone try something like this on one of their pedals?

Look at the Ibanez tube screamer circuit, it's the same as that.

try some schotkyz  that will blow your gord..

The mod is somewhat specific to the Direct Drive...  for example, if you made this mod to your TS-9 clone you would hear absolutely no difference.

More mods for the Barber Direct Drive are at http://www.barberelectronics.com/Tweaks%20page.htm

regards, Jack

Also check out the simple mods page on from my main page.

I'm still curious about Fred Nachbauer's passive compression scheme in his Dogzilla amp. That one uses a series of diodes with a bunch of parallel resistors determining how much voltage drop there is for signals of different amplitudes.  From what I gather, that arrangement is not intended to produce obvious clipping (although any sort of diode arrangement would likely induce *some* minimal coloration).

i remeber readin about that mark but at the time i didn't think too much about it. now ya got me interested...