MOSFET Distortion Circuit 1 PUBLIC

MOSFET Distortion Circuit 1 with 2-Band Tone

High-gain distortion circuit using one dual DMOS op-amp IC for primary distortion voice and four dual MOSFET ICs for another two MOSFET distortion voices. Controls Include: Input Gain, Input Level, Driver Gain, Drive, Dist 1 enable switch, Dist 1 symmetry switches (two, with 2 settings each), Dist 1 Depth, Bass, Center, Treble, Dist 2 enable switch, Dist 2 symmetry switches (two, with 2 settings each), Dist 2 Depth, and Volume. Frequency Range 40 Hz to 16 kHz with all controls at 50%. Suitable for 6/7-string guitar or 4-string bass. [Not recommended for 8-string guitar or 5/6-string bass.] Maximum Gain = +32 dBV @ 1.6 kHz with all controls at 50%, or up to twice that with all controls at 100%. [Do not use the circuit will all controls at 100% except briefly as a worst-case scenario while breadboard testing.] Distortion can be obtained by overdriving the Input Stage (IC1a) which can in-turn overdrive the Driver Stage (IC1b), to obtain overdrive. This is CMOS distortion, said to be tube-like. Additional distortion is from discrete MOSFETs configured to work like diodes in two different arrays; one shunt-type hard-clipping array, for one MOSFET voice, and one feedback-type soft-clipping array, for another MOSFET voice. The symmetry switches set the harmonic content of respective MOSFET voices. Note that neither MOSFET array affects gain in a perceptible manner, but provide clipping, adjusted by the Depth controls. IC6 is specified as a dual BJT op-amp IC that has a reputation for sounding more like a 12AX7 dual-triode preamp tube than any other dual op-amp IC. However, the circuit may be too noisy for some users. Determine this by comparative listening tests while breadboarding. For less noise, use an OPA2134PA dual FET-input op-amp IC instead of IC1 or IC6, or both. Power-supply not shown. Requires a dual-polarity DC supply providing +-9VDC or +-12VDC or +-15VDC at >=80 mA of current. And though simulator verified, treat the circuit as experimental. Breadboard test before committing to a soldered build. House in a grounded metal enclosure.