RO Experimental 3-Tube Fuzz PUBLIC

Richter Original Experimental 3-Tube Preamp With Fuzz

Richter Original 3-tube preamp circuit with 2-voice shunt-diode fuzz. Controls Include: Input Level, Bass, Treble, Notch, Fuzz 1 enable switch, Fuzz 1 symmetry switches, Fuzz 1 Depth, Fuzz 2 enable switch, Fuzz 2 symmetry switches, Fuzz 2 Depth, Drive, and Volume. Circuit is intended to provide 5-stage overdriven-tube distortion plus two separately enabled shunt-diode fuzz tones; one from standard silicon diodes and one from Schottky diodes, where the symmetry switches determine the harmonic content of the fuzz. Here, the input can be overdriven using a boost or overdrive stomp-box, while Q2 can be overdriven by Q1, depending on the setting of the Input Level control. Note: Sound will be like that of a 12AU7 dual-triode tube. Q3 can be overdriven by Q2, depending on the settings of the Tone controls, while Q4 can be overdriven by Q3 but whose output is affected by the Notch control (a simple high-cut tone-control). Note: Q3 gives triode distortion, but Q4 gives tetrode distortoin. The Fuzz sounds should have little / no affect on overall gain, though the project is not meant to provide extreme gain. Finally, Q5 can be overdriven by Q4, depending on the setting of the Drive control. Note: Q5 gives pentode distortion, like that of an American output tube (e.g., 6V6). The final output tonality is intended to be like that of an American-made boutique guitar-amplifier. Note: The specified tubes were designed to have their plates AND heaters operated from a single +12VDC car battery. Power-supply not shown. Requires a regulated single-polarity +12VDC supply providing >= 1A of current. Experimental circuitry. Untested design. No simulation, though each portion of the design is based on proven circuit from various sources (RCA Receiving Tube Manual, Guitar-Amp schematics, etc.). Frequency response and overall gain must be determined during breadboard testing. House project in a grounded metal enclosure, to prevent EMF interference. Rack-mount implementation with vibration-damping mounts is recommended. Example Power-Supply: 12V DC 1000 mA Regulated Power Adapter, Product ID: 798. $8.95 each. From AdaFruit website. https://www.adafruit.com