RO Tube-Type Guitar Preamp PUBLIC

Richter Original Tube-Type Guitar Preamp

Richter Original tube-type guitar preamp using one 12U7 dual triode (not 12AU7) and one 12EA6 pentode. Controls Include: Drive 1, Drive 2, Bass, Mid-Center, Treble, and Volume. Triode section design by Kurtus Richter. Pentode section based on original 1952 Baxandall tone-control circuit. Mods involve different pentode, use of Center control, replacement of tapped Treble pot by two ganged pots, and inclusion of the Volume control. Experimental circuitry. No simulation. Untested design. Frequency response and overall gain must be determined during breadboard testing. For distortion, Q1 can be overdriven by a boost or overdrive pedal, Q2 can be overdrive by Q1, depending on the setting of the Drive 1 control, and Q3 can be overdriven by Q2, depending on the settings of Drive 2 and the Tone controls. Distortion sounds should be similar to those from an American-made tube-type guitar amplifier. Power-supply not shown. Requires a regulated single-polarity DC supply providing +12VDC @ >= 750 mA of current. House project in a grounded metal enclosure. Rack-mounting and vibration damping recommended.