This circuit was originally put together on request from a small independent guitar store in the area. While putting everything together the store went out of business, so the original idea fell through, but I did build a prototype unit which have been very well received within my small circle of friends.

workhorse_0_3The circuit is, for those of you who recognize it, very much based on the Centaur circuit, which seems to be everyone’s favorite effect these days. But rather than build a number of straight off copies, a discussion with the store about customer requests and demands produced a list of modifications to the original circuit.

– Separate boost.
– Treble boost option, not just treble cut.- True-bypass and no battery.

Workhorse 2.1In addition to the stated requests I wanted to cut down on the parts count, and use standard values as much as possible, as well as give the effect somewhat more gain.

After some experimentation I decided that with the gain increase, coupled with the inclusion of a new treble control, taking C12 out of the equation by default and bringing it back in for a “boost” worked quite well without affecting the parts count much.

I’ve also replaced the treble control with the treble side from a baxandall tone stack, adjusted to my liking. I know, this actually added more parts, but I liked it so it would have to do.

All in all I am quite happy with how it sounds.

Workhorse buildWorkhorse gut shotWorkhorse circuit

I’ve built only two so far. Ronny Yttrehus of Captain Gone is using one, and I passed the other one on to one of the greatest guitar players in existence (here’s to hoping it actually reached him) just here the other day. I’ve received several requests already, and am contemplating building a few (read “less than ten”), besides building another one for myself. And now you can build one as well!

There’s also an extended PDF version of the layout that includes a trace cut diagram amongst other things:

Adobe_PDF_file_icon_32x32Note: The previous issues with the layout missing parts of the component list has been resolved, and the layout image has been updated.


Add a Comment
  1. The voltages should be similar to the Klon, and I do believe I posted voltages for that one.

  2. It’s possible to have ic’s voltage? I don’t have sound from mine. I hear a clock beat from the gain pot…Thanks!

  3. It takes C12 somewhat out of the circuit, a cap that would normally shunt some of the bass to ground, allowing more of the “bottom” of the signal through. You could try a variable resistor here, but I’m not sure how well it would work. Worth tinkering with, though 🙂

  4. So, because I’m a bit dense.. looking at the schematic, the boost isn’t a separate circuit but lowers the amount of signal going to ground, making for more output. The end result is that the boost won’t do anything if the pedal is bypassed, similar to MB’s DeadringerV1 and BoneardV1

    Could R14 be replaced with a pot for a variable amount of boost?

  5. The 7660 voltage chip comes in many different varieties. One of the few options that really does matter is the “S”, as without it the chip “works” within the audible range producing an oscillating sound. With the “S” postfix the chip “works” at double the frequency, which puts it outside the range of the human ear, i.e. no annoying oscillations.

  6. Thanks for this creative circuit. The layout mentions the charge pump needs “S-postfix.” What is it?

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