RO SpaceGroove Guitar Preamp II PUBLIC

RO "SpaceGroove" Guitar Preamp II w. Tube & Diode Fuzz

Richter Original "SpaceGroove" guitar preamp version 2, with real tube fuzz, diode fuzz, and 3-band tone. This is the same as the first version except for the addition of a shunt-type clipping Diode Array. Controls Include: Gain, Diode-Fuzz enable switch, Diode-Fuzz symmetry switches 1 & 2, Diode-Fuzz Trim switch, Drive, Bias, Bass, Mid, Treble, Bright switch, Mid Boost switch, Deep switch, Stack Sum, Attenuation, and Volume. Fuzz comes from overdriving the tube with sufficient Gain and Drive settings and/or enabling the Diode Array. Frequency Range 8 Hz to 16 kHz with all controls at 50%, or 4 Hz to >20 kHz with all controls at 100%. Maximum Gain = +19 dBV @ 1 kHz with all controls at 50%, or +25 dBV @ 1 kHz with all but Tone controls at 100%. Note: Tone controls have subtle effects but Attenuation control has significant effect when set < 50%. Project is suitable for 6/7/8-string guitar or 4/5/6-string bass. Power-supply not shown. Requires +12V DC @ >= 550 mA, filtered unregulated or unfiltered if regulated. Schematic verified valid by CircuitLab's Frequency Domain Simulation using a MOSFET subcircuit configured to simulate the 12K5 tube's subcircuit. [See: RO SpaceMOS Guitar Preamp.] Note: The 12K5 is a space-charge tube designed to be operated from a +12V DC supply-voltage on heater AND plate. It was chosen due to having a reputation for being the 12V space-charge tube that sounds more like one triode from a 12AX7 twin triode preamp tube than any other space-charge tube. However, though simulator verified, the circuit should be considered experimental. Breadboard test before committing to a soldered build.