Фонокорректоры — Pro-Ject Phono Box MM

The Phono Box MM is the plain moving magnet preamplifier in the Box Design range of the Austrian turntable company Pro-Ject Audio Systems. It exists for the many modern amplifiers that ship without a cartridge input, taking the tiny signal from the stylus and bringing it up to line level for an AUX or similar socket. The MSRP is EUR 79 including VAT, the finish is black lacquer, and Pro-Ject adds that it also accepts moving coil cartridges of the high output kind next to MM types.

Key specs that matter

The input presents 47 kohm in parallel with 120 pF, and there is a single fixed gain of 40 dB, which means a 5 mV signal at 1 kHz leaves the box as 500 mV. Pro-Ject quotes a noise floor of 88 dB A-weighted and total harmonic distortion under 0.04 percent. Deviation from the RIAA curve is held within 0.5 dB across 20 Hz to 20 kHz. There is one pair of RCA sockets in and one pair out. The unit runs from an outboard 18 V, 500 mA DC adapter, draws only 20 mA while working and stays below 1 W in standby. The case is 107 mm wide, 30 mm high and 75 mm deep, and it weighs 280 g without the adapter.

Engineering and use context

Inside, the two channels are built as separate dual mono circuits so that left and right stay apart, and the amplification uses low noise integrated circuits. A metal enclosure screens the electronics against vibration and electromagnetic fields, and because the mains transformer lives in the wall adapter rather than inside the case, hum from the power stage is kept away from the phono input. The gold plated connectors resist corrosion over years of plugging and unplugging. There are no switches for load, capacitance or gain, so nothing needs adjusting before first use. The small footprint lets the box stand right beside the record player, which keeps the unamplified cartridge lead short before the signal is equalised and raised by a factor of one hundred.

Pairing

A typical moving magnet cartridge rated for around 5 mV output fits the fixed gain and reaches a normal line level. High output moving coil designs of similar voltage can also be connected, but low output MC cartridges need a step-up device or a stage with 60 dB or more. The line level result suits the AUX or tape socket of an integrated amplifier, a preamplifier, a receiver or a set of powered speakers.

Alternatives

For an even simpler setup, Pro-Ject offers its Phono Box E, an MM only stage in the entry E line, using SMD construction and internal shielding in a 120 x 32 x 100 mm case.