Powderkeg - A CDWillis Circuit


Breadboard Baker
@cdwillis has been cooking up a pretty neat tonebender/muff baby. If you'd like to read more about it you can here.

Anyways, this is one of his boards and honestly, it doesn't disappoint. It's not quite a muff, but not quite a tonebender. It's really somewhere between the two. What honestly piqued my interest in this one was the bias control. I see them scattered here and there, but never took the time to try it out on my own; breadboard or otherwise. There are 4 controls: Toan, Volume, Attack, and Bias. Toan is a muff tone stack. The ATTACK control limits the amount of signal going into the circuit and is essentially your guitar's volume knob. Yes, the tone changes for more colors to work with. As you dial back the BIAS control, the volume starts to drop and slowly transitions into glitchy/velcro fuzz territory. I should probably try this circuit out with a lower voltage and see what happens similar to a SAG control.

I did, however, do 1 modification on the stock circuit. IMO, most muff controls are too extreme for me in either direction: ice pick highs in one extreme and flubby lows. Not a reflection on CDWillis, just my personal preference. What I did, at least for now, is added sockets and changed the tone stack to a mid-hump based muff stack. You can find those part values in the build doc of the Muffin Crumb Tone Control Stage. For the record, that build doc is incredible handy to have.

The enclosure is unfinished for now, but the circuit works and is in a box. Oh, and this circuit came with a 3PDT breakout board to include the LED. Stupid me measured and drilled for the LED from the wrong side of the enclosure, but a few short wires later and problem solved. No problems with the build board itself.

Hats off to you @cdwillis . This is a pretty cool circuit. If you're super nice to him maybe he'll share his gerber files or any spare boards he may have.

Funny thing, even after I made the 3pdt breakout board I ended up drilling one of my enclosures the wrong side too 😅

I'm really happy you tried it out and tweaked it. I was trying a flatter mid range on the muff tone control originally, but ended up compromising with the Russian muff values. I think cutting a little more high end and a little less bass would make it sound better, but then you end up with a more scooped EQ profile. Adding a mid control like the Hoof is probably the best compromise.

My favorite part of the circuit is balancing the attack and bias controls.

I still have a few more boards if anyone wants one, just let me know