Unison Research Phono One

Tube Phono Preamplifier

€ 2.690,00 Price include 21% VAT Price exclude VAT € 2.223,14

AVAILABILITY: 1 WEEK

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The original Phono One phono stage was one of the most admired and beloved products in Unison Research history. When production was discontinued some years ago, the requests for a replacement never ceased. For that reason, we decided to improve and reintroduce this design. We retained the exterior appearance of the original since we have always considered this design to be timeless, its aesthetic appeal is still undiminished and best left untouched. While the circuit used in the Phono One has many features in common with the more affordable Simply Phono, one more valve has been added, bringing the number of triodes (i.e. five ECC83/12AX7 double triodes) up to ten. All of the gain stages now implement a parallel configuration for the best noise and distortion performances. This solution increases also the overall gain to approximately 54dB, enough for all MM and most MC cartridges. The same passive RIAA network has been adopted, but with specially selected components that ensure strict tolerances to the equalization curve. Increased values for the output capacitors improve bandwidth and phase rotation at low frequencies. In order to avoid the problem of DC voltage and bump during the warm up and switch off time of the unit, a delayed muting function has been implemented. This way the output is disabled until the tubes reaches their optimal temperature. In addition, loud bumps at switch on and switch off are also avoided. In the Simply Phono, only the resistive component of input impedance is selectable. With the Phono One, both resistance and capacitance can be matched to the requirements of any cartridge for the best performance. A dedicated free location on the PCB allows the installation of custom value resistors in order to set the interface parameters even at any non-common values. Particular care has been dedicated to the power supply design. In order to minimize cross-talk and inter-stage interference, an independent RC filter cell has been placed near every gain stage, thus reducing the cross-talk (especially at low frequencies). This cell results in more than a 20dB reduction in comparison to the already extraordinary performance of the Simply Phono. In the new Phono One, low frequency cross-talk is practically immeasurable at less than -90dB. A careful design of the layout improves channel separation and interference rejection, and an elastic suspension of the amplifier board helps bring the sonic performance of the new Phono One to a supreme level of natural detail and musical clarity. As expected for a no-compromise design, all the supply voltages are regulated and heavily filtered. Nothing has been neglected in the overall design: all of the signal wiring is hand-soldered using shielded wire, the placement of the valves addresses the mechanical micro-distortion of the physical parts of the tubes when operated in horizontal position, and oversized power components and adequate cooling ensures high reliability. We are sure the new Phono One will be highly appreciated by anyone looking for a phono preamplifier that offers a highly involving listening experience.

Specifications

- Type: Stereo Phono Valve preamplifier

- Class: pure A

- RIAA : passive +/- 0.1 dB (20 Hz / 20 KHz)

- Output Impedance: 800 ohm.

- Outputs: 1 x line

- Gain : 54 dB

- Total Harmonic Distorti on (THD): 0.1 % at 1 volt output

- Signal to Noise Ratio (S/N): – 80 dB

- Inputs: 1 per fonorivalatore MM o MC

- Input Impedance: 47 Kohm – 100 – 50 – 22 ohm / 100 – 200 – 320 – 420 pF ( modifiable )

- Feedback factor: 0 dB.

- Valves: 5 x ECC83 / 12AX7

- Alimentatore: esterno

- Dimension: 37.3 x 5.84 x h 24.63 cm.

- Net Weight: 3.6 Kg circa (including power supply)

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Unison Research Phono One

Tube Phono Preamplifier