RO 4-Stage RCA Tube Preamp PUBLIC

Richter Original 4-Stage Tube Preamp Using RCA Circuits

Richter Original 4-stage tube preamp using RCA circuits. Controls Include: Input Level, Drive, Bass, Mid-Center, Treble, and Volume. Design based on two circuits from the 1965 RCA Receiving Tube Manual # RC-24, pages 544 and 545; "Two-Stage Input Amplifier" and "Bass and Treble Tone-Control Amplifier". Not meant to provide much gain but rather overdriven preamp-tube distortion, expected to sound like 12AU7 dual triodes but operable with +12VDC plate and heater supply voltages (the 12U7 was originally designed to work directly from a car battery). Experimental circuitry. No simulation. Untested design, though based on proven circuits from the RCA manual. Frequency response and overall gain must be determined during breadboard testing. Power-supply not shown. Requires a regulated single-polarity DC supply providing +12VDC @ >= 750 mA of current. Rackmount implementation is recommended, with vibration damping for a grounded metal enclosure.