RO MOS-Man Distortion Circuit PUBLIC

Richter Original "MOS-Man" Distortion Circuit for Guitar

Richter Original "MOS-Man" high-gain distortion pedal for 6-string electric guitar. Controls Include: Input Gain, Tone, Drive, Output Gain, Intensity, Trim, and Volume. Uses two depletion-mode MOSFETs to obtain distortion when overdriven (to simulate overdriven output tubes). IC1 and IC2 were chosen to ensure clean op-amp operation at all control settings. However, if overdriven op-amp distortion is desired, in addition to MOSFET distortion, keep IC1 as is but consider the following substitutes for IC2. For JFET distortion, use the TL082CP. For more MOSFET distortion, use the OPA2156IDR. For tube-like BJT distortion, use the NJM5532M (the Japanese version of the NE5532N, but don't use the NE version, it does not sound tube-like). Here, the input signal is stabilized by an input buffer then gain boosting is applied, followed by the Tone control which has a significant effect on gain as well as tone (higher frequencies involve increased gain). The MOSFETs come in a dual IC package, with M1 overdriven based on the settings of the Input Gain and the Tone controls, while M1 will overdrive M2. This is followed by the Drive control, another gain stage, the Intensity control, and the Trim pot, which has little effect at or below a 50% setting but cuts upper highs when < 50%. The output stage is yet another gain stage but with fixed gain. Frequency Range 45 Hz to 14 kHz with all controls at 50%, or 16 Hz to supersonic with all controls at 100%. [Do not use the circuit with all controls at 100%. Keep pots between 10% and 80% of clockwise rotation.] Caution! This is an extreme high-gain circuit when all controls are set > 50%. Maximum Gain = +23.4 dBV @ 400 Hz with all controls at 50%, or +101 dBV @ 1 kHz with all controls at 100%. This means the circuit shifts into the "high-gain fuzz" category when all control settings exceed 50%. A 12V battery is shown for the power-supply but it should be replaced by a regulated single-polarity DC supply providing +12VDC @ 80 to 100 mA. And though simulator verified, treat the circuit as experimental. Breadboard test before final soldering.