Help With A Schematic

Swap the 4k7 and 470 ohm resistors on the collector of the second transistor, though that may give TOO much signal.

Play with it. What will it do, distort? How will you know?

GG

You beat me to it, but I was going to suggest moving the output capacitor from the two resistors' node to the resistor-collector connection. This gives it that extra fraction of a dB output level.

You may not know whether it's that circuit or the one that it's driving that's distorting, but as long as the user is happy with it, who cares? I wonder about the low input impedance of that thing, the 22k resistor is too low by itself, but there's also the forward-biased base-collector junction of that first stage. With the highly inductive output of standard guitars, this can cause reduction in higher frequencies. OTOH, some may find that desirable, and a buffer on the input would make them say "you ruined it, now it sounds too twangy." Sometimes a "good" electronics designer can't win for losing, and the guy that make a piece of crap ends up selling millions of units.

I'd put a 10k pot in for the 10k. Doesn't it control the gain of the second transistor?

second

I think the circuit has all the gain it can have. The gain of the second stage is huge (4k7 in C against 10uF in E), so if you need more output, change the ratio of the 470 and the 4k7 resistor on the collector of T2. Replace it with a 5k pot and you probably can produce 9V square waves.

Meindert

It appears to me that you could just move the output capacitor to the collector of the second transistor. After you do that, you could probably also ditch the 470-Ohm resistor.

Good luck.

--Mac