Split-Supply Preamp 5 PUBLIC

Split-supply guitar preamp with 3-band tone and boost circuit.

Split-supply guitar preamp with 3-band Fender-style tone-stack, signal boost circuit, and auxiliary buffered output in addition to a normal output. Controls Include: Input Attenuation enable switch (Attenuate or Direct), Attenuation control, Boost enable switch, Boost Gain, Boost Level, Bass Cut switch, Low Knee switch (2 settings), Drive control, Bass, Mid, Treble, Stack-Sum, and Volume. Usable Range: 75 Hz to 16 kHz, with emphasis on mids and highs from 250 Hz to 2.5 kHz. Intended for 6-string electric guitar in standard tuning. Not suitable for 7/8-string guitar or bass-guitar. Maximum circuit gain = 22.5 dBV @ 400 Hz with all controls at 50%. Maximum circuit gain = 28 dBV with Boost Gain control, R19, at 100% but all other controls at 50%. For more overall gain, to use circuit as an overdrive, replace Stack-Sum control, R13, as follows. With R13 = 500k, max gain = 27.5 dBV for R19 at 50%, or 32.6 dBV for R19 at 100%. With R13 = 250k, max gain = 30.2 dBV for R19 at 50%, or 35.5 dBV for R19 at 100%. With R13 = 100k, max gain = 32.2 dBV for R19 at 50%, or 37.4 dBV for R19 = 100%. Do not change other component's values except as needed or desired during breadboard testing.