Colorsound / Sola Sound Tonebender MKII Professional

The Sola Sound/Colorsound Tonebender MKII Professional is probably the second most famous Fuzz box after the Fuzz Face. It's a three transistor fuzz circuit that creates an unholy amount of gain and sustain. For an idea of how it sounds - Jimmy Page used one with his Dragon Telecaster from the Led Zeppelin 1 era, yes, it's THAT tone. Sola Sound also produced the circuit for Vox, Marshall and RotoSound. These units were named the Vox Tone Bender Professional MKII, Marshall Supa Fuzz and RotoSound Fuzz Box. For a really detailed history of the Tonebender series of pedals check out this:  http://www.stompboxes.co.uk/History.html from David Main of D*A*M (A guy who really does know fuzz boxes!).

[an original Marshall Supa Fuzz]

[three original Vox Tonebenders]

[a Tonebender MKII circuit with Mullard OC81 germanium transistors]

Here's a 1968 advertisement:

And here's a receipt for Jimmy Page's Tonebenders from SolaSound!

And here's a video of the D*A*M Tonebender MKII Professional in action, I think you'll agree it sounds pretty mind/ear/sense destroying:

Now here's the schematic. Here you can see the three transistor layout. As with any simple fuzz circuits the transistor type and gain is a huge factor in deciding the overall tone of the unit. It's recommended that the gain of Q1 ~ 70hfe with Q2 ~ 70-90hfe and Q3 ~ 100-120hfe. I've built many Tonebenders with many different type of transistors. Always use a germanium transistor for Q1, then you can experiment with low gain silicon transistors. Experiment and have some fun, you'll certainly find a decent fuzz tone or two! For some more detail on exact circuit operation and mods visit: http://fuzzcentral.ssguitar.com/mkII.php

Here's a PCB layout available from Tonepad: http://www.tonepad.com/getFile.asp?id=86

References:

1) http://www.led-zeppelin.org/joomla/studio-and-live-gear/312
2) http://fuzzcentral.ssguitar.com/mkII.php
3) http://www.stompboxes.co.uk/History.html
4) http://theheliopolisofblossius.wordpress.com/2011/06/12/tone-bender-mkii-build/