Big Muff tone bypass

[Mark Hammer]

I was repairing an op-amp Big Muff for a buddy the other night.  Actually sounded pretty decent to me.

Whomever he got it from has miswired the tone bypass switch, so after some detective work, I figured out where the wires were supposed to go to, wired it up and fired it up.  What's interesting is that, since the traditional BMP tone control eats signal level via passive bleed, going directly from the clipping stage output to the volume control allowed for the unit to be a lightly coloured boost.  That is, even with the Sustain control way down, there was still enough signal level when the tonestack was removed, to push the amp hard if you wanted to.

The other thing that was interesting, although I suppose it may be well-known to others, is that the tonestack on this issue provides negligible midscoop in the middle position.  So, flicking the bypass switch essentially keeps the tone, if the control is set to midpoint, and boost the output.

You know, now that I think of it, I neglected to keep a DC-blocking cap between clipping stage output and volume pot in the unit I repaired.  I better tell my buddy to hold off on using it just yet.