Modified Seely Preamp PUBLIC

Highly Modified '97 Seely Preamp for Guitar

Guitar preamp based on circuit by Rodrick Seely from the article "Chrome Classic 50" guitar-amplifier in Popular Electronics mag., Dec. 1997, p34. However, I imposed many modifications, including adding an extra dual op-amp IC, altering circuitry, and changing part-values to get a preferred response curve. See the original circuit here: https://www.worldradiohistory.com/Archive-Poptronics/90s/97/PE-1997-12.pdf In my version, the controls are: Clean Level, Bass, Treble, Distort enable switch, Distort Trim, Distort Drive, Distort Tone, Distort Gain, Distort Level, Fuzz enable switch, Fuzz symmetry switches (two, with 2 settings each), Fuzz Depth, Output Gain, and Volume. Range at or above 0 dBV is from 22 Hz to 19 kHz, with emphasis on mids and highs. Suitable for 6/7/8-string guitar and 4/5/6-string bass, in standard tuning. Gains depend on whether the Distortion circuit is enabled. Maximum gain without Distortion is +14 dBV @ 2.5 kHz with all controls at 50%, or +69 dBV with all controls at 100%. Maximum gain with Distortion ON is +15.2 dBV @ 1kHz with all controls at 50%, or +69.2 dBV @ 6.3 kHz with all controls at 100%. The Fuzz affects only Distortion; cutting it by 7.1 dB with Depth control at 100% (zero), or by 5.5 dB with Depth at 50% (halfway), or by 3 dB with Depth at 0% (maximum resistance). Power-supply not shown. Requires a regulated dual-polarity DC supply providing +-9VDC or +-12VDC or +-15VDC at >= 60 mA of current. And while based on a proven circuit, plus simulator verified, treat the circuit as experimental. Breadboard test before soldering.