Фонокорректоры — Pro-Ject Phono Box S2 Ultra

The Phono Box S2 Ultra is a discrete MM and MC preamplifier that Pro-Ject Audio Systems derived from its Phono Box Ultra 500 and brought into the regular S2 line. The MSRP is EUR 249 including VAT, and the unit is offered with a silver or black front. Pro-Ject built it without any operational amplifiers, an approach it had first tried in the Tube Box S2.

Key specs that matter

Gain is switchable in four steps, 40 or 43 dB for moving magnet cartridges and 60 or 63 dB for moving coil types. Four load resistances are provided - 10 ohm, 100 ohm, 1 kohm and 47 kohm - together with two capacitance values of 100 and 220 pF. The subsonic filter is switchable and attenuates by 18 dB at 20 Hz. Pro-Ject specifies 89 dBV signal to noise in MM mode, THD of 0.00052 percent and RIAA accuracy within 0.4 dB from 20 Hz to 20 kHz. Audio goes in and out on a single pair of RCA connectors each. The external 18 V DC supply is rated at 500 mA while the stage itself needs 80 mA. The case is 103 mm wide, 37 mm tall and 119 mm deep, and it weighs 570 g without the power supply.

Engineering and use context

Every gain stage is made from discrete components rather than integrated op-amp chips. The RIAA network uses polystyrene capacitors, a type Pro-Ject singles out as especially suited to phono equalisation, and the equalisation itself is split into separate sections so the response can follow the RIAA curve closely. A solid metal casing shields the circuit from outside interference. All settings are made with small switches, so the load, gain and filter are fixed once for a given cartridge. Compared with the standard Phono Box S2 in a case of almost the same size, the Ultra has a steeper subsonic slope, fewer capacitance steps and a distortion figure roughly twenty times lower. Pro-Ject names the Accu Box S2 as the compatible upgrade supply for owners who want to replace the wall adapter.

Pairing

Standard MM cartridges suit the high impedance position at the lower gain steps, and moving coil designs use the three low resistance loads with the higher gain steps. The RCA outputs feed any unbalanced line input, so the box works with integrated amplifiers, preamplifiers and active speakers, and its small size lets it sit next to the turntable.

Alternatives

The Pro-Ject Tube Box S2 is an op-amp free MM and MC stage from the same maker that adds two replaceable ECC83 valves and a FET input stage.