RO Imperatore I Amplifier Part 1 PUBLIC

Preamp Section for RO Imperatore I Guitar Amplifier

Preamplifier section for RO Imperatore I guitar amplifier. Controls Include: Input Gain, Drive, Bass, Mid, Treble, Intensity, Fuzz 1 enable switch, Fuzz 1 symmetry switches, Boost, Fuzz 2 enable switch, Fuzz 2 symmetry switches, Fuzz 2 Depth, Output Gain, and Volume. Both fuzz voices are from Schottky diodes. Fuzz 1 is from a feedback diode array, while Fuzz 2 is from a shunt diode array. ICs were chosen to provide tube-like distortion when overdriven. For clean input op-amp operation, substitute an OPA2134PA for IC1, or clean overall operation except for fuzz, substitute for both ICs. Note: Do not use a low input impedance dual op-amp IC for IC1, such as that specified for IC2. Keep IC1 input impedance >= 1G. Frequency Range 13 Hz to 3 kHz with all controls at 50%, no fuzz, or 20 Hz to 5 kHz with Fuzz 1 on, or 20 Hz to 4 kHz with Fuzz 1 and 2 on, or 30 Hz to 3.5 kHz with Fuzz 1 off, Fuzz 1 on. Otherwise, 8 Hz to 25 kHz with all controls at 100%, Fuzz 1 on or off, Fuzz 2 off. Suitable for 6/7/8-string guitar or 4/5/6-string bass. Maximum Gain = +26 dBV @ 100 Hz with all controls at 50%, no fuzz, or +70 dBV with all controls at 100%, no fuzz, or +80 dBV with all controls 100%, Fuzz 1 on, Fuzz 2 off. Bass control range +-7 dBV. MId and Treble ranges +-11 dBV each. Power-supply not shown. Requires a regulated dual-polarity DC supply providing +-9VDC or +-12VDC or +-15VDC @ >= 50 mA of current. A power-supply is provided at this site for the RO Imperator I amplfier which includes an op-amp supply together with a power-amp IC supply. Alternatively, an off-the-shelf op-amp supply is available online. The Acopian DB12-10, dual-polarity +-12VDC, 100 mA, enclosed, linear, regulated, commercial grade. DigiKey # 5006-DB12-10-ND. https://www.digikey.com . 195.64 dollars US. Or 180.00 factory direct. https://www.acopian.com . And though simulator verified, treat this circuit as experimental. Breadboard test before final soldering.