RS-Timbre "JGMD1 Booster" PUBLIC

JFET-Input Booster with Fuzz & Distortion

TS-Timbre "JGMD1 Booster". JFET-input booster circuit with diode fuzz and op-amp distortion. Control Include: Input Gain, CMOS Gain 1, CMOS Gain 2, Fuzz Enable switch, Fuzz symmetry switches, Tone Drive, Bass, Center, Treble, and Volume. The JFET in the Input Stage can be overdriven to produce extra distortion. The germanium BJT in the Gain Stage can be overdriven using the Input Gain control. [Note: The obsolete AC128 can be obtained on dBay.com or at Amazon.com.] IC1 in the CMOS stages has op-amps with MOSFET inputs but BJT outputs, and can be overdriven to provide pleasing tube-like MOSFET distortion. IC2 is a low-noise dual op-amp that should not be overdriven, though IC2a provides Fuzz from Schottky diodes in its feedback loop, which can be enabled or disabled. With Fuzz disabled, that stage functions as an extra gain stage. IC2b makes the tone-stack active and serves as the Output Stage. The circuit's frequency range is from 32 Hz to > 20 kHz. Maximum gain with all controls at 50% is +22.6 dBV @ 1 kHz, and twice that with all controls at 100%. The circuit can be for a stomp-box or rackmount project, suitable for 6/7-string guitar or 4-string bass (not recommended for 8-string guitar or 6/7-string bass). The battery can be replaced by a regulated single-polarity DC supply providing +9VDC or +12VDC or +15VDC at >= 60 mA of current. And though simulator verified, treat the circuit as experimental. Breadboard test if before committing to a soldered build. And house in a grounded metal enclosure.