Split-Supply Preamp 4 PUBLIC

Split-supply guitar preamp with 3-band tone and 3-voiced fuzz.

Split-supply guitar preamp with Fender-style 3-band tone-stack and 3-voiced hard-clipping diode-based fuzz matrix. Controls Include: Input Attenuation enable switch (Attenuate or Direct), Attenuation control, Fuzz enable switch, Fuzz Clip control, Fuzz Type switch (Mellow, Normal, or Bright), Fuzz Depth control, Drive control, Bass, Mid, Treble, Stack-Sum, Gain, and Volume. Max gain = 26.7 dBV @ 4 kHz with all controls 50%. Max gain >= 32 dBV with controls 100%. Moderate gain circuit, usable as signal booster with 3-band tone and 3-voiced fuzz. Fuzz voices are from choice of diodes: LEDs (bright, high-level), silicon (normal, standard-level), germanium (mellow, low-level). Each diode array in the diode matrix also has symmetry switches; two with 2 settings each, determining harmonic content of the fuzz. The Clip control affects the shape of the clipped part of the fuzz waveform, and the Depth control affects fuzz intensity (where more intense reduces volume, while less intense increases volume, with Fuzz enabled). For more gain, to make this an overdrive circuit, the Stack-Sum control, R16, can be replaced as follows. With Gain pot 100%, 250k pot as R16 gives 35.7 dBV @ 4 kHz for moderate overdrive, while 100k pot as R16 gives 38.6 dBV @ 4 kHz for strong overdrive.