VOX: Tone Bender MKIII With Treble N Bass Boost

This has absolutely nothing in common with a regular MKIII Tone Bender - literally nothing - well, apart from the name and the enclosure used.  

The Vox Tone Bender MKIII with Treble 'n' Bass Boost is a tone control, followed by a Fuzz Face style fuzz, set to full fuzz.  There's only two knobs - volume and treble n bass.   

The original switching only turned the fuzz section on and off, and adjusted the gain from the first stage.  It left the tone control in the signal path at all times....  but why?   Definitely not true bypass.   Perhaps this is why they never really caught on.

A history lesson can be found here - fuzzboxes.org

VOX TONE BENDER MKIII WITH TREBLE N BASS BOOST - VERO LAYOUT

This is quite close to the original, I did take a couple of liberties to make it slightly less difficult to build, and I did completely ignore the ridiculous switching on the original.

Note that I probably could not have done this without using the schematics and layout done by Sonic VII on the D*A*M forum and the photos posted on fuzzboxes - so credit where credit is due.

POTS

The pot values have been listed as unconfirmed in a few posts - looks like 100k and 5k.  The 5k is a bit weird, but there it is.  (photo from fuzzboxes.org)

A 5k pot has way less output level, despite the photo above, I'd run with 100k for volume.  Perhaps the 5k was a replacement pot, maybe they wanted it with low output?  Who knows?

INPUT AND COUPLING CAP

So which is it?  220n or 22n?   These are clearly 22n.

But this looks to be 0.22uf - using my really bad photo editing 'skills' to enhance the photo.  

photos care of https://www.effectsdatabase.com/model/vox/colorsound/tonebender/mk3/treblebassboost

Based on the LTspice sim, I'd stick with 220n.  22n doesn't have enough bass response.  Yet to get this on a breadboard to test via ears.

SCHEMATIC

Without the weird switching, and using the 220n caps with a 100k output pot

VIDEO DEMO