freestompboxes.org

Hullo.
I've been putting together my own od circuit when I noticed something a bit odd: when I added the master pot (I tried 22K, 100K, 500K and 1M) it actually acts as a volume pot of a tube amp (meaning that u have to crank it to get overdrive). Well, I know this is a common thing and in most analog fxs I used or built it is so. But in this particular case the impact on the sound is huge! I get little to no overdrive with the master at low levels even when the circuit's gain is at max. Then, when I bring the master level to 10/10 I get the full ammount of distortion... yes, that's ok, but the volume gets too high and basicly makes the thing unusable in an fx chain.

Is there a way to make a proper master controll without it acting as a gain pot at the same time?

PS: just screwing around I measured my amp's input impedence, it' 1M. And then I realized that by putting any master pot at the fx's output the impedence is 0 ohm at min level and would go as high as 500K if I used a 1M pot for instance. The circuit is at it's best when there is no master pot at all and the signal is fed to the amp straight from the output cap... hmmm hmmm

That probably means that the overdrive sound you're getting is because, well, *ejem*, you're over-driving your amp input.
So your circuit is really working as a booster (mainly amplifying the guitar signal without overdriving it much by itself) but as the output of the circuit is really hot, it makes the preamp in the amplifier to distort.

Can you post a schematic? Regards

Juanro

• Q1 2N5088
  Q2 2N5088
  
  R1 33K
  R2 2M2
  R3 470R
  R4 100K trim
  R5 100K
  R6 2M2
  R7 470R
  R8 1M
  R9 100K trim
  
  C1 10n
  C2 22u
  C3 100n
  C4 47u
  C5 100n

Collector voltage set at 4.5V. Trims should be substituted with pots and the Vc range would be from 2 to 7V (low Vc = high gain)