Dual Overdrive Switching Question

[idsnowdog]

I have built two small low-gain overdrive circuits that I would like to combine into a single pedal. Choosing between A or B can be done by putting a three-pole on/on switch on either the input or output. However, routing A into B and B into A is more complicated. I would like as few switches as possible. Does anyone know of a circuit I could adapt to do this?

 

[Chistopher]

A 5 way rotary switch would be a pretty simple way to do A,B,A->B, B->A, A||B if you can fit it in the enclosure. Then use footswitches to turn each side on or off. The only other way I think you would be able to do it would be two smaller toggle switches, one to control which or both sides are on, and the other to choose between series and parallel in the 'both on' position.

Does having A->B and B->A mean all that much to you? If both sides of the OD are the same or very similar circuit, you may not benefit too much more from having both routing options over the simplicity of only having one

 

[idsnowdog]

Circuit A is a JFET/MOSFET overdrive and Circuit B is a Germanium overdrive. They each sound great on their own and are very different from each other. They sound great together but B into A, or A into B sounds very different. A blend pot would give three sounds but the two stages would be in parallel and I haven't tested that.

 

[jeremy]

the fulldrive 3 for example has a clean boost and an od, theres a switch to change the order. ive had other pedals that had similar options. i have a way huge camel toe mkii, that i wish had that feature.

 

[idsnowdog]

The last pedal I built was supposed to be an Electra distortion clone with a Germanium transistor and hard clipping diodes. I was pleasantly surprised by how much overdrive I got out of the circuit but the output impedance was too low to drive clipping diodes. If I raised the output impedance the clippers worked but there was too much volume loss and it sounded constipated. So I built a second cascaded gain stage with another Germanium transistor to drive the clipping diodes. This was very successful. At the same time, I was reading about JFET overdrive circuits and how "tube-like" they were. So, I built a Fetzer Valve on my breadboard and ran the Germanium transistor into the JFET gain stage. The results were interesting so I built another pedal to experiment with.

I built another Germanium gain stage based on an LPB1 boost. Once again I was surprised by how much gain I got from a single Germanium transistor. I added a gain control and it turned into a wonderful overdrive circuit. Think Neil Young Powderfinger at Farm Aid or Cortez The Killer. Thick, warm, and chewy. It cleans up beautifully with my guitar's volume control. This circuit can stand alone if I want it to.

The Fetzer Valve based circuit took more work. The 2N3819 JFET I used was bright and lacked output. I tried a 2N5848 and 2N5847 without much difference. However, the JFETs have great touch sensitivity and you can go from clean to distorted by picking harder. I tried dozens of different clipping diodes but there was too much loss of clarity and volume. I tried cascading into a second stage but that didn't work and I couldn't devise a gain control that worked correctly. So, I tried a cascoded MOSFET and that was far more successful. I also tried cascoded BJTs and they worked well but I lost too much touch sensitivity. The 2N7000 MOSFET I used filled in the bass, midrange, and added volume without adding distortion. Think Son Volt or Tom Petty. Bright, raspy, and jangly. It could also stand on its own but with only a volume control it would be a one-trick pony.​

 

[Chistopher]

Honestly, a single dpdt could do series/parallel, and another one could control the order. That's how I would do it if a rotary wasn't an option. No room for a blend though with that, and it would take up to 3 moves to get from one setting to another.

 

[idsnowdog]

I have these 12-position switches.

https://www.digikey.com/en/products...DZ8cc6TdWyd4BJF37MeI9sXgEHs-cbIBoCB6kQAvD_BwE

 

[idsnowdog]

This will probably work.