Фонокорректоры — Audio Research Reference Phono 10

The Reference Phono 10 is the first two-chassis phono preamplifier in the history of Audio Research, a Minnesota company that has built phono circuits since its founding in 1970 and released its first separate phono unit in 1992. The model number mirrors the Reference 10 line stage, and the design draws on work done for the Reference Anniversary and Reference 10 preamplifiers.

Key specs that matter

Gain is switchable between Low and High, giving 51 dB or 74 dB at 1 kHz from the balanced outputs and 45 dB or 68 dB single-ended, and the maker rates it as MM and MC compatible. Two sets of inputs are provided. Standard input impedance is 47k ohms with 100 pF, and further loads of 1000, 500, 200, 100 and 50 ohms can be selected, plus a Custom value set at the factory to order. RIAA accuracy is within 0.2 dB from 10 Hz to 60 kHz, with the 3 dB points below 0.3 Hz and above 300 kHz. Distortion is under 0.002% at 1 V RMS output. Equivalent input noise is 0.22 uV in Low gain and 0.055 uV in High gain. Maximum input is 250 mV RMS at 1 kHz, and output capability reaches 80 V RMS balanced or 40 V single-ended. Output impedance is 200 ohms single-ended and 400 ohms balanced.

Engineering and use context

This is a true dual-mono design with fully separate channels from the power supply onward, including separate high and low voltage transformers per channel and energy storage twice that of the Reference Phono 2. Twenty stages of electronic regulation are used, with vacuum-tube regulation for each channel from two 6550C and two 6H30P tubes, and dual umbilical cords link the supply box to the audio chassis, whose mains inlet is a 20 A IEC type. The audio circuits are fully discrete, pure Class A and run without feedback. Eight 6H30P dual triodes form the low gain section, while the high gain section uses special low-noise FETs in place of a step-up transformer. The input circuit lets the RCA inputs operate in balanced mode without an inverter. Besides RIAA, early Columbia and Decca curves are selectable. A 7 inch touch screen handles inputs and their names, equalisation, loading, gain, muting, display colours and tube hours, and the metal remote duplicates these functions. Front and side panels are brushed, anodised aluminium, and both tops are perforated acrylic.

Pairing

The recommended following load is 50k to 100k ohms and 100 pF. Power draw is up to 235 W, with 0.8 W in standby.

Alternatives

Audio Research also offers the PH9, a one-box tube phono preamplifier built on three 6H30P gain tubes and five selectable cartridge loads.