Friday, 22 June 2012

Soda Meiser Pedal Build

Earlier in the year I built a Tube Screamer clone from a kit, pleased with the result and feeling more ambitious I thought I'd try building another design. This time I picked the more exotic Devi Ever Soda Meiser; it's a fuzz pedal with a wide range of gain and the ability to create some very strange, broken sounds.

The other reason for this choice is that Devi has published the schematic for this pedal, which along with the stripboard/vero layout, guided my build. If you're using this stripboard layout be warned that while the legs of the transistors are labelled correctly the MPSA18 transistors I bought have the flat side on the other side to that show in the layout, so double check the data sheet before you solder them into place. All the components were bought from, apart from the enclosure which I got from Gap Co.

I made a minor adjustment and added a switch which allows me to toggle between chaos and noise modes on the pedal by removing the 2.2mĪ© resistor or the 0.1uF capacitor. In normal fuzz mode both are left in. (After making the layout change I discovered this is sold as a Noise Floor.) This was done with a DPDP on-on-on switch, where the middle position connect both components.

The trickest part was getting my head around wiring in the true-bypass 3PDT footswitch. While circuit layout is nice and neat on the stripboard, the other wiring quickly becomes confusing as they cross over each other. As you can see from the gut-shot, I was very generous with the connecting wires, nervous that I'd end up stuck with the board somewhere it couldn't sit.

I attached a battery clip but used it only for testing. The DC jack is has the nut on the inside, so to use that for testing would mean unsoldering it, then re-soldering it once I'd fitted it into the enclosure. The enclosure base is screwed shut, making changing the battery a bit long winded, but my pedals are all usually powered from a 9V supply on the pedalboard, so it'll be unused most of the time.


The cardboard around the edge of the board had to be added to stop it shorting out against the metal of the enclosure, this wasn't helped by the plentiful wires pushing the board against the pedal's base.

The end result is very, very fuzzy; just as you'd expect. I'm not sure how much I'll use it in my regular playing, but I really enjoyed putting it together.