PH3

About the PH3

The Audio Research PH3 is a high-fidelity hybrid stereo phono preamplifier introduced in 1995. It employs a fully single-ended design from input to output, combining a low-noise J-FET input stage with class A operation vacuum-tube gain using three 6922 twin triodes. The PH3 provides a fixed total gain of 54 dB, suitable for phono cartridges with outputs of 0.25 mV or higher, and is intended to be used with active line-level stereo preamplifiers that provide an additional 12 to 18 dB of gain. Input impedance is factory-set at 47K ohms with 90 pF capacitance, but both can be adjusted via resistor and capacitor changes to optimize matching with various cartridges. The unit features gold-plated, audiophile-grade single-ended RCA connectors for inputs and outputs. It offers excellent frequency response (±0.15 dB of RIAA from 10 Hz to 60 kHz), very low distortion (<0.005% THD at 0.5 V RMS, 1 kHz), and extremely low noise (0.1 µV equivalent input noise, IHF weighted). The PH3 uses electronically regulated low and high voltage power supplies and requires 28 watts maximum power. Dimensions are 19" W x 5.25" H x 10.25" D, and it weighs approximately 10 lbs. The It remains a respected classic phono stage for audiophiles seeking tube sound with low noise and precise RIAA equalization.