Parallel-Stage Op-Amp Distortion PUBLIC

Parallel-Stage Op-Amp Distortion Circuit with 2-Band Tone

Distortion circuit for guitar featuring one clean stage and one distortion stage operated in parallel, along with active 2-band James-style tone controls. Intended for 6/7-string electric guitar. Controls Include: Drive, Clean Gain, Clean Level, Distortion Gain, Distortion Level, Bass, Mid Center, Treble, and master Volume. Frequency Range between 0 dBV reference-points is from 50 Hz to 10 kHz with all controls at 50%, but bandwidth increases when controls are set > 50%. Maximum gain = +20.8 (Vo/Vi = 10.7) @ 515 Hz with all controls at 50%, or +49.1 dBV (Vo/Vi = 285) @ 2.5 kHz with all controls at 100%. Here, a high-fidelity op-amp is used as a clean input buffer driving two other op-amps; one configured as a clean boost for the input signal (and which should be difficult to overdrive), while the other is a distortion stage meant to be overdriven with sufficiently high gain. The clean and distorted signals are mixed in a tone stage, which can also be overdriven, depending on signal amplitudes from both of the paralleled stages. The Treble control cuts 10 kHz down to -11 dBV from 0 dBV, or boosts it up to +5 dBV. The Center control does not affect gain but shifts the center of the midrange passband higher or lower in frequency. The Bass control cuts 100 Hz down to +4.7 dBV from +13.7 dBV, or boosts it up to +18.2 dBV. Power-supply not shown. Requires a regulated dual-polarity DC supply providing +-9VDC or +-12VDC or +-15VDC at >= 40 mA of current. And though simulator verified, treat the circuit as experimental. Breadboard test before soldering.