Volume Drop in pedals AFTER the Fuzz

[Bassmanfox]

Hey,
Well I'll keep it simple.  I made a Pedal similar to the Big Muff for bass.  I liked it a lot, but it needed some "tweaks"  I added a switchable diode section and a switchable tone cap.  Plus I made the last transistor a Mpsa13 and tweaked it to give more gain.  The only problem is now when I engage the fuzz then engage another pedal down the line, there is a significant volume drop, but once I disengage either pedal the volume drop goes away.  Down the line from the fuzz I have a Octave, Univibe and delay, each seem to do it, especially the vibe.  the weird thing is it didn't do this before when I had the "untweaked" fuzz.   Also I have another opamp fuzz and that doesn't cause a volume drop with ANY of the pedals down the line.  I have a feeling it has something to do with impedance, but I dunno, any suggestions?  Thanks ahead of time...

[BlueToad]

What did you change in the last stage? If you dramatically increased Rc on the final gain stage, that would increase the output impedance. If you then connect that to a device with a low input impedance, such as a univibe, there's effectively a voltage divider formed between Zout of the muff and Zin of the vibe or whatever. You might consider adding a buffer after the final stage, either a simple emitter follower with another BJT, or the discrete or opamp buffers from GGG. The latter options would save you from having to redo any of the layout. That's the first thing I would try. Actually, I don't know that I'd have the guts to try to increase the gain of a BMP, but to each his own
Carl