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Phono Preamp Valve - tube design (added 4/02)

Phono Preamplifier - Simple circuitry suitable for moving-magnet cartridges; Passive high-frequency equalization...(schematic / circuit added 6/07)

Phono Preamps For All - Various circuits for moving coil and moving magnet pickups  (schematic added 6/07)

Phono RIAA Preamp - Very high quality moving magnet phono preamp, few circuits will better this one.  (schematic added 6/07)

Phonograph Disc Playback PreAmplifier  - (diagram added 6/03)

Portable Microphone Preamplifier - High headroom input circuitry. 9V Battery powered. (added 9/04)

Preamp/ Crossover Muting Circuit - Muting circuit suitable for all line-level applications.  (schematic added 6/07)

PreAmplifier for Microphone or Guitar Use - suitable for guitar or microphone use. (added 7/03)

Preamplifier Power Supply - Uses External AC Adapter. Safe and effective, low noise and no hum! (PCB replaced by P05A)  (schematic added 6/07)

Quality Microphone Pre Ampl. using the Model 425 Opamp  - (diagram added 6/03)

RCA BA-1A two-stage preamp schematic - (electronic circuit added 2/07)

RCA BA-21A preamplifier schematic - (schematic / circuit added 2/07)

RCA BA-31A preamplifier schematic - (diagram added 2/07)

RIAA Equalized Stereo Phono Preamp - (electronic circuit added 4/05)