HyperSound 2: Overdrive with Fuzz PUBLIC

Overdrive Circuit with 2-Band Tone and Optional Fuzz

Clean overdrive circuit with 2-band tone and optional fuzz. Based on the preamp for the High-Power FET Stereo Amp by Leo Simpson and John Clarke, Radio Electronics mag., July 1986, p57. However, many modifications were made from the original schematic, including adding an extra op-amp, altering circuitry, adding controls, and changing part-values to increase the overall gain and obtain a preferred frequency response curve. Controls Include: Drive 1, Input Gain, Bass, Treble, Drive 2, Fuzz enable switch, Fuzz symmetry switches (two, with 2 settings each; for setting harmonic content of fuzz), Fuzz Depth, Output Gain, and Volume. Frequency Range between -3 dBV corners is 50 Hz to 17 kHz with all controls at 50%. Intended for 6-string electric guitar (not recommended for 7/8-string guitar or bass-guitars). Maximum Gain = +30 dBV @ 1 kHz with all controls at 50%, or +53.6 dBV with all controls at 100%. This qualifies the circuit for being in the overdrive category. Specified IC chosen to ensure clean operation at any control settings with fuzz off. 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 it before committing to a soldered build. Notes: Fuzz is standard classic kind from silicon diodes. For softer fuzz, replace the IN4001s with Schottkys (e.g., 1N5819G). For brighter fuzz, use red LEDs (e.g., LTL-307E). And to add overdriven op-amp distortion, keep IC1 as is but substitute one of the following for IC2. For JFET distortion, use a TL082CP. For MOSFET distortion, use an OPA2156IDR. Or for distortion similar to that of a 12AX7 preamp tube, use an NJM55332M (i.e., the Japanese version of the NE55332N). However, with all three of these choices, audible noise may be an issue. Perform listening tests while breadboarding to compare substitutes and determine if noise becomes a mitigating factor.