Dimetrodon Distortion - A Classic Hybrid Distortion Pedal

In my update about a week ago, I included some teasers for upcoming pedals that I had not yet included on the blog. One of these was the Steggo-san Overdrive which I featured a few days ago. In terms of overall appearance, that is still one of my favorite pedals. In terms of sound, today's pedal ranks right up there. The Dimetrodon Distortion combines the classic MXR Distortion+ circuit with the tone stack from a Big Muff Pi creating something of a hybrid pedal. I've worked up a couple of different prototypes of this design so far, and I think I've decided which way I want to go long-term, because if offers me the widest range of options for this particular circuit going forward.

For the first prototype I'm using the Effects Layouts Distortion+ trace as well as their Big Muff Tone Stack layout. If you want to use this particular Distortion+ layout, do read the comments because there are three fairly significant typos on the capacitors - three of the film capacitors are labeled a uF when they should be nF. There are also two versions of the tone stack, I use the one with gain recovery to keep the signal strength high.

Because of the afore mentioned typos on the documentation, I didn't get a good picture of the populated PCBs for the original prototype as I'd put the wrong caps in, but got a really funky sound! From the photo above you can see both boards populated and the reason that we prototype! First my wiring is a bit of a dog's breakfast because I didn't know exactly how everything was going to line up. Second, it seems as if I reversed which side the tone knob should be on. Fortunately both boards are small and I was able to angle everything into the enclosure without bumping up against any of the jacks. I included a stereo jack on the input in case I wanted to add battery functionality later on. 

The photo above contains the boards for the second prototype. Instead of using the straight Distortion+ board, I've migrated over to Effects Layouts' Drivestortion board. These can be etched individually or purchased for a very reasonable price - so for now I've gone with buying. If it turns out I want to make a lot of these, I may license the full version. The reason I've transitioned to the Drivestortion version is because it supports a total of six versions of the Distortion+ circuit:

• DOD '77 Grey 250
• MXR '80 Distortion+ / Ross Black Distortion
• DOD '82 Yellow 250
• Ross Tan Distortion
• DeArmond Square Wave
• DOD YJM308

This gives the project a lot of potential for customization on the distortion side of the circuit. However, the BMP Tone stack board can also be built in a total of six versions:

• Triangle
• '73 Ram's Head
• '75 Ram's Head
• Russian Ukrainian
• A "Flat Mids" variant
• A "Mids bump" variant

The latter two remind me a little of the AionFX Halo which offers a total of three "mids" settings on their version of the Big Muff Pi (stock, hump, flat).

My first builds combine the MXR '80 Distortion+ with the '75 Ram's Head Tone Stack. However, between the two boards I have a total of 36 different combinations of distortion and tone stack that could be customized for the user.

For the enclosure, this one is still an homage to the Pete Cornish pedals, with a very happy dimetrodon, this won't be the final artwork for this particular enclosure. I have something else in the works that I think will be awesome - so watch this space. In addition to the art changes, the potentiometer orientation will change so that the PCBs will line up better within the enclosure. That being said, if you like the Distortion+ (and I do!) the added tone control gives it a very cool new dimension that I'm already taking advantage of.