HV-1 & HV-1a Nuvistor Pre-Preamplifier

Introduced April 1981, HV-1a in January 1983

The HV-1 Pre-Preamplifier was the first active phono pre-preamplifier from conrad johnson. It was a simple linear gain stage designed to provide the added gain required by low output moving coil cartridge. The HV-1 used the latest in vacuum tube technology, the nuvistor. Nuvistors are small metal-enclosed triode vacuum tubes noted for their extraordinary linearity and low noise.

RF Filters and traps were judiciously executed to minimize noise and external interference, two things that made many other pre-preamps unacceptable in audiophile systems. Twin cascaded voltage regulators rejected AC line fluctuations and a separate regulator for the filament supply ensured large dynamic range and excellent frequency response.

The HV-1a update included upgraded coupling capacitors and an improved power supply regulator. The result was greater depth and spatial detailing.

HV1 & HV1a- V1 - V2: 6CW4 Replacement Tube Set RTHV1


Input Impedance 100 ohms (phono overload 200 mV at 1kHz)
Gain: 28 dB
Distortion: less than .05% THD or IMD
Response: bandpass 20Hz to more than 20kHz
Tube Complement: 2 X 6CW4
Mechanical: chassis 19" X 3 _" x 10 1/8"
Weight: 6 lbs.