RO Guitar Preamp 8: Boost with Fuzz PUBLIC

Richter Original Guitar Preamp 8: Booster with 2-Voice Fuzz

Richter Original guitar preamp, version 8; booster with 2-voice diode fuzz and active Baxandall tone. Controls Include: Input Level, Gain, Fuzz 1 enable switch, Fuzz 1 symmetry switches, Fuzz 1 Depth, Drive, Fuzz 2 enable switch, Fuzz 2 symmetry switches, Fuzz 2 Depth, Bass, Treble, Trim, and Volume. Enabling either fuzz has little / no effect on overall gain. Specified IC is the OPA2134PA dual FET-input op-amp IC, chosen to ensure clean op-amp operation without fuzz. For overdriven op-amp distortion in addition to diode fuzz, consider the following substitutions. For JFET fuzz, use the TL082CP. For MOSFET fuzz, use the OPA2156IDR. For tube-like BJT fuzz, use the NJM5532M (the Japanese version of the NE5532N). [Note: Each substitution will involve increased noise. Conduct listening-test with desired IC while breadboarding to determine if noise is an issue.] Frequency Range 22 Hz to 5.6 kHz with all controls at 50% but no fuzz, or 5 Hz to 20 kHz with all controls at 100% but no fuzz, or 10 Hz to 10 kHz with all controls at 100% and full fuzz. Suitable for 6/7/8-string guitar or 4/5/6-string bass. Maximum Gain = +20 dBV between 250 Hz and 400 Hz with all controls at 50%, or +57.5 dBV with all controls at 100% but no fuzz, or +38 dBV with all controls at 100% and full fuzz. Power-supply not shown. Requires a regulated dual-polarity DC supply providing +-9VDC or +-12VDC or +-15 VDC @ >= 25 mA of current. [Note: Higher supply voltage results in lower op-amp noise.] And though simulator verified, treat the circuit as experimental. Breadboard test before committing to a soldered build. House project in a grounded metal enclosure.