Audio Research PH-1 (1990–1994)

Most of what survives on the Audio Research PH-1 comes from hobbyist sources and online reference pages. No factory literature or period review with measurable data has surfaced in the research for this archive. What is known suggests it was a tube phono preamplifier produced from 1990 to 1994 (one source gives an introduction of 1989/1990), part of Audio Research's Linear Reference series.

The PH-1 is a fully balanced, dual-mono design with separate power supplies for each channel. It uses two 6DJ8/ECC88 tubes per channel, a J-FET input stage, and no overall feedback. The circuit is described as all-FET and fully symmetrical throughout. Volume is handled by passive L-pads - one for MM/MC selection and a linear volume pot. Vishay resistors are used in critical signal paths.

Specifications recorded from online sources: input sensitivity is 200 µV (MC) and 1.5 mV (MM), gain is 50 dB (MC) and 60 dB (MM), input impedance is 47 kΩ, output impedance is 500 Ω, and maximum output is 20 V RMS. Frequency response is given as 5 Hz - 100 kHz, distortion as 0.01%, and signal-to-noise as 75 dB (MC) / 85 dB (MM). Dimensions are 19 × 5.25 × 11.5 inches (W×H×D). Weight is 18 lbs and power consumption is 30 watts. The original list price is not documented. One source values the unit at around $400, in what appears to be a 2009 reference. An owner reports that microphonics can be an issue - tapping the chassis is audible through the speakers - but considers that a sign of a good tube unit.

The PH-1 appears in a dealer showcase in Audio (June 1994, p.98), but no full review with test data has been located. If you own a PH-1 or have literature - a manual, a review, or factory specs - the Archive would welcome a correction.