Unison Research Phono One Stereo Phono Valve Preamplifier at Vinyl Sound Buffalo, NY USA

The Phono One is a pure Class A stereo phono valve preamplifier from Unison Research (Treviso, Italy), available at Vinyl Sound in Buffalo, NY, USA. Originally one of Unison Research's most popular products before being discontinued, the Phono One has been reintroduced with a new and improved circuit design while retaining its classic, timeless aesthetic. Using five ECC83 (12AX7) double triodes operating in pure Class A, the Phono One achieves a passive RIAA equalization accuracy of ±0.1 dB from 20 Hz to 20 kHz -- tighter than the Simply Phono's ±0.2 dB. A gain of 54 dB and a signal-to-noise ratio of -80 dB confirm the Phono One as the higher-specified of Unison Research's two tube phono preamplifiers, with switchable input impedance settings of 47k ohm, 100 ohm, 50 ohm, and 22 ohm, plus switchable input capacitance of 100, 200, 320, and 420 pF for precise MM cartridge optimization.

Five ECC83 Tubes with Passive RIAA and Zero Feedback

The Phono One's additional fifth ECC83 tube -- compared to the Simply Phono's four -- provides an extra gain stage that contributes to the improved 54 dB gain and the significantly better -80 dB signal-to-noise ratio. The completely passive RIAA equalization network remains at zero feedback (0 dB), preserving the open, phase-coherent character associated with passive equalization topologies. The passive RIAA accuracy of ±0.1 dB across the full 20 Hz to 20 kHz audio band -- tighter than the industry-standard ±0.5 dB target typically specified by competitive products -- ensures that the tonal balance of vinyl recordings is reproduced with the fidelity intended by the recording engineer. THD is 0.1% at 1 V output, a quarter of the Simply Phono's 0.4% figure at the same level. The external power supply reduces the risk of mains noise coupling into the sensitive first gain stage and removes the transformer's magnetic field from proximity to the phono signal circuit.

Comprehensive Cartridge Loading with Four Capacitance Settings

The Phono One's four switchable capacitance settings -- 100, 200, 320, and 420 pF -- address the cartridge loading requirement for moving-magnet designs more systematically than most competitive phono stages. MM cartridges exhibit a resonant peak at high frequencies whose exact position and magnitude depend on the interaction between the cartridge's inductance and the combined capacitance of the tonearm cable and phono stage input. The correct capacitance load is specified by the cartridge manufacturer (typically between 100 pF and 400 pF) and selecting the nearest available setting on the Phono One brings the cartridge's high-frequency resonance to the intended position, ensuring the treble balance is reproduced as the cartridge designer intended. Four resistance loading settings -- 47k, 100, 50, and 22 ohms -- serve MC cartridge loading with the same precision.

Key Features

• Five ECC83 Pure Class A Tubes: Five 12AX7 double triodes in pure Class A throughout the gain chain, including an additional stage compared to the Simply Phono for improved gain and noise performance.
• ±0.1 dB Passive RIAA Accuracy: Tighter than industry-standard specifications, ensuring tonal balance accuracy from vinyl sources with exceptional precision.
• 54 dB Gain: Sufficient for MM and mid-to-high output MC cartridges; higher gain than the Simply Phono's 52 dB.
• -80 dB Signal-to-Noise Ratio: Substantially lower noise floor than the Simply Phono's -72 dB, preserving very low-level groove detail and musical decay.
• 0.1% THD at 1 V Output: Quarter the distortion of the Simply Phono at the same output level.
• Switchable Impedance and Capacitance: Four resistance settings (47k/100/50/22 ohm) and four capacitance settings (100/200/320/420 pF) for precise MM and MC cartridge optimization.
• External Power Supply: Dedicated external power supply eliminates mains transformer noise coupling and magnetic interference with the phono signal circuit.
• Zero Feedback: No negative feedback applied anywhere in the signal path, preserving phase coherence and the natural open character of Class A tube amplification.

Technical Specifications

Frequently Asked Questions

What is the Unison Research Phono One?

The Unison Research Phono One is a pure Class A stereo phono valve preamplifier from Treviso, Italy, using five ECC83 tubes with a passive RIAA network accurate to ±0.1 dB (20 Hz to 20 kHz). It provides 54 dB gain, -80 dB signal-to-noise ratio, 0.1% THD at 1 V output, switchable impedance (47k/100/50/22 ohm), switchable capacitance (100/200/320/420 pF), and an external power supply. It is the higher-specified of Unison Research's two tube phono preamplifiers.

How does the Phono One compare to a solid-state phono stage like the Pro-Ject Phono Box DS3 B?

The Unison Research Phono One's pure Class A tube topology -- five ECC83 valves, zero feedback, passive RIAA -- produces a sound character associated with harmonic warmth and natural decay. The Pro-Ject Phono Box DS3 B is a solid-state design with an active RIAA network and discrete FET input stage, offering a more neutral, extended high-frequency presentation. The Phono One's -80 dB SNR and ±0.1 dB RIAA accuracy are competitive with any phono stage at its level, but the choice between the two ultimately reflects a preference for tube or solid-state harmonic character rather than a specification advantage for either design.

Can the Phono One accommodate very low-output moving-coil cartridges?

The Phono One's 54 dB gain is appropriate for cartridges with an output of 0.4 mV or higher -- which includes many mid-output MCs such as the Ortofon Quintet Black, Hana ML, and Dynavector DV-20X2L. For cartridges below 0.3 mV -- such as the Ortofon MC Anna, Lyra Etna, or Koetsu Rosewood Signature Platinum -- a step-up transformer (SUT) ahead of the Phono One's 47k ohm input position is recommended to bring the signal to a level within the Phono One's optimal gain range.

What is a passive RIAA equalization network, and why does it matter?

Vinyl records are cut with the RIAA equalization curve -- bass is reduced and treble is boosted during cutting to fit more music on a record and reduce surface noise. A phono preamplifier must apply the inverse curve during playback. In an active RIAA design, this equalization is applied through a negative feedback loop around an amplifying stage. In a passive design like the Phono One's, the equalization is applied by a purely passive RC network with no active feedback loop. Passive RIAA implementations are associated with lower phase distortion and a more natural tonal quality, at the cost of requiring more gain stages to compensate for the signal attenuation in the passive network.

Where can I buy the Unison Research Phono One in Buffalo, NY or the USA?

The Unison Research Phono One is available at Vinyl Sound in Buffalo, NY, USA. Vinyl Sound is an authorized Unison Research dealer serving customers across western New York and the broader United States. Contact the Vinyl Sound team for current availability and advice on cartridge compatibility and system matching.