RO Fuzzy Overdrive PUBLIC

Richter Original Fuzzy Overdrive with 2-Band Tone

Richter Original high-gain Fuzzy Overdrive circuit with 2-band James-style tone-stack, adjustable midrange centering, and 2-voice diode fuzz. Controls Include: Input Level, Bass, Center, Treble, Gain, Drive, Fuzz 1 enable switch, Fuzz 1 symmetry switches, Fuzz 1 Depth, Fuzz 2 enable switch, Fuzz 2 symmetry switches, Fuzz 2 Depth, and master Volume. The Center control sets midrange center-frequency between 400 Hz and 1.6 kHz but does not provide mid boost or cut. Fuzz 1 is from standard diodes in a feedback array, while Fuzz 2 is from Schottky diodes in a shunt-type array. The symmetry switches (SSw) set the harmonic content of their respective fuzz sounds. [Note: Enabling either Fuzz has no discernable effect on overall circuit gain.] Frequency Range between the -3 dBV corners, using a 1V 1kHz input signal, is from 30 Hz to 13 kHz with all controls at 50%, or 16 Hz to 40 kHz with all but the Tone controls at 100%. Suitable for 6/7/8-string guitar or 4/5/6-string bass. Maximum Gain = +38.7 dBV @ 1 kHz with all controls at 50%, or +73 dBV with all but the Tone controls at 100%. The specified ICs ensure clean op-amp operation at all control settings when the diode arrays are disabled. However, if overdriven op-amp distortion is desired in addition to fuzz, keep IC1 as is and substitute one of the following for IC2. For MOSFET distortion use an OPA2156IDR, or for very tube-like distortion use an NJM5532M. However, either substitution will involve a noticeable increase in noise. Power-supply not shown. Requires a regulated dual-polarity DC supply providing +-9VDC or +-12VDC or +-15VDC at >= 40 mA of current. [Note: Higher supply voltage results in lower op-amp noise.] And though simulator verified, treat the circuit as experimental. Thoroughly breadboard test it before committing to a soldered build. House in a grounded metal enclosure.