MUSITRONICS: Mu-Tron Micro V

The Musitronics Mu-Tron Micro V is a cool old auto-wah / envelope filter from the seventies - I feel I need to be wearing a valour tracksuit, possibly with a half-unzipped jacket exposing generous chest hair with a gold dangler to really play this properly.  Maybe a moustache too...   

I've used a LM13700 instead of the near impossible to find CA3080 (real ones that is).  In the thread on DIY Stompboxes there's a reference to changing the 1M resistor on the collector of Q2 to 470k / 500k for a better sweep (I have not tested this yet).

If you're interested in how envelope filters work and have some spare time to read and wrap your head around this, here's an excellent reference by Mark Hammer.

MU-TRON MICRO V  - VERO LAYOUT

This one is verified.  Note the two sides of the LM13700 are tied together.  I'm yet to test them being split.  In the thread, they say that it just sounds a bit sweeter with both sides running together, so I'll probably leave it that way.

It did take some filing to make it fit, but I did manage to fit it in a smaller than planned enclosure.

ORIGINAL SCHEMATIC 

VIDEO DEMO