Split-Supply Preamp 2 PUBLIC

Split-Supply Guitar Preamp with 3-Band Tone and Diode Fuzz.

Split-supply high-gain guitar preamp with Fender-style 3-band tone-stack, and hard-clipping germanium-diode fuzz. Controls Include: Input Attenuation enable switch (Attenuate or Direct), Attenuation control, Fuzz enable switch, Fuzz Clip control, Fuzz symmetry switches (two with 2 settings each), Fuzz Depth control, Drive control, Bass, Mid, Treble, Stack-Sum, Gain, and Volume. This is an "overdrive" circuit. Highest gain with all controls at 50% is 32 dBV (Vo/Vi = 43.7) @ 2.5 kHz, or 37.5 dBV (Vo/Vi = 75) with all controls at 100%. For yet more gain, change rated value of Stack-Sum control R13 to 500k, for 42 dBV (Vo/Vi = 126) @ 2.5 kHz. Make no other changes except when breadboard testing. Frequency range is from 25 Hz to > 20 kHz. Suitable for 6/7/8-string guitar or 4/5/6-string bass, with emphasis on highs.