20W Practice-Amp with 3-Band Tone PUBLIC

20W Practice-Amp with 3-Band Fender-Style Tone-Stack

20-Watt RMS solid-state practice-amp circuit for 6-string electric guitar. Controls Include: Bass, Mid, Treble, Stack Sum, Pre-Gain, Post-Gain, and Volume. No fuzz, distortion, or other effects. Range at or above 0 dBV for IC1 with all controls at 50% is from 130 Hz to 1.3 kHz, while 63 Hz is down by -12 dBV and 10 kHz is down by -4 dBV. Yet, turning all C1 controls past 50% increases overall gain, and also expands bandwidth in both directions; e.g., from 40 Hz to > 20 kHz with all controls at 100%. Yet, IC2 provides additional gain up to +22 dBV extra, which also expands bandwidth further. The circuit is intended only for 6-string electric guitar. Maximum gain for IC1, at the input of IC2, is +8.7 dBV @ 400 Hz with all controls at 50%, or +49 dBV @ 630 Hz with all controls at 100%; enough to overdrive IC2. [Do not use the circuit will all controls at 100% except as a brief worst-case scenario while breadboard testing.] The power-supply is shown in the diagram. And though simulator verified, treat the entire circuit as experimental. Breadboard test before committing to a soldered build. House circuit in a grounded metal enclosure but shield the transformer from the rest of the circuitry. The speaker should be a guitar-speaker rated 20-watts RMS or greater, with 8-ohms impedance (though IC2 will also tolerate a 4-ohm load). Example: Celestion "Ten-30" Creamback, 10", 30W, 8-ohm. Parts Express # 294-2472. $49.50. https://www.parts-express.com