RO High-Gain Booster PUBLIC

High-Gain Booster with Diode Fuzz and 2-Band Tone

Richter Original High-Gain Booster with feedback diode fuzz, 2-Band James-style tone-stack, adjustable midrange centering, and both normal and buffered outputs. Controls Include: Input Level, Bass, Center, Treble, Gain, Drive, Fuzz enable switch, Fuzz symmetry switches, Fuzz Depth, and Volume. The Center control sets midrange center-frequency between 400 Hz and 1.6 kHz. The Fuzz symmetry switches (two, with 2 settings each) determine the harmonic content of the fuzz. When enabled, the Fuzz diodes do not noticeably affect the overall gain of the circuit, and the Buffered Output is at the same level as the Normal Output but has opposite phase (the Normal Output is in-phase with the input signal). Frequency Range between the -3 dBV corners, and using a 1V 1kHz input signal, is from 24 Hz to 15 kHz with all controls at 50%, or 12 Hz to 63 kHz with all but Tone controls at 100%. Suitable for 6/7/8-string guitar or 4/5/6-string bass. Maximum Gain = +30.7 dBV @ 400 Hz with all controls at 50%, or +59 dBV @ 1.6 kHz with all but Tone controls at 100%. The specified ICs ensure clean op-amp operation at all control settings, so only the Fuzz effect involves distortion. However, if overdriven op-amp distortion is desired in addition to fuzz, keep IC1 as is but 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 result in a noticeable increase in noise. Power-supply not shown. Requires a regulated dual-polarity 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. Breadboard test before soldering.