The original Phono One ranks among the most popular models in Unison Research's history. After production ended, requests to bring it back were so numerous that the brand reintroduced it with a revised and improved design. It keeps the look of the first version, with a curved wooden top above a vented black chassis. The unit measures 373 mm wide, 59 mm high and 246 mm deep.
Five ECC83 (12AX7) valves amplify the signal in pure class A, with no negative feedback. Passive RIAA equalisation holds the curve within ±0.1 dB between 20 Hz and 20 kHz, for 54 dB of gain. Signal-to-noise ratio is 80 dB and harmonic distortion 0.1 % for 1 V output. The line output, with an impedance of 800 Ω, delivers up to 40 Vrms at 5 % distortion.
The input accepts an MM cartridge or a high-output MC above 2 mV. Two DIP switches next to the input sockets select the load resistance, 47 kΩ, 100 Ω, 50 Ω or 22 Ω, and the capacitance, 100, 200, 320 or 420 pF. The settings table is screen-printed on the rear panel, next to the RCA sockets and the ground terminal.
At switch-on, the Phono One mutes its outputs while the valves warm up, shown by an orange LED on the front. About 30 seconds later the LED turns green and the outputs open. The dedicated external power supply connects at the back, and in laboratory tests the valves exceeded 1500 hours of operation. 2-year warranty, valves guaranteed for 3 months.
Data sheet
Specific References
DualCS 618Q quartz-stabilized direct-drive turntable: automatic tonearm lift and stop, dual-gimbal tonearm, Ortofon 2M Blue cartridge, and heavy cast-aluminum platter. Tracking error within ±0.07%.
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