Фонокорректоры — Soulution Audio 755

The 755 is a phono preamplifier from Soulution Audio, the Swiss high-end electronics brand. Unlike Soulution's earlier 750 and 751 phono stages, it adds a precision volume control and a wideband output stage taken from the 725 preamplifier, so it can drive power amplifiers directly in a vinyl-only system as well as feed a line preamplifier.

Key specs that matter

Inputs are two MC and one MM, all unbalanced RCA, with outputs on balanced XLR and unbalanced RCA. MC input impedance is adjustable from 10 ohms to 1 kilohm, and MM impedance from 47 ohms to 47 kilohms with capacitance from 0 to 750pF. Maximum gain is 78dB balanced (72dB unbalanced) for MC and 66dB balanced (60dB unbalanced) for MM. Frequency response extends from 0Hz to 1MHz (-3dB), THD+N is below 0.002% from 20Hz to 20kHz and signal-to-noise ratio is 100dB. The volume range is 0 to -79dB in 1dB steps, output impedance is 2 ohms and output voltage reaches 16V balanced. Power consumption is 60W in use and below 0.5W in standby, with a 12V LINK remote turn-on. The chassis measures 480 x 167 x 450mm and weighs about 30kg.

Engineering and use context

Moving-coil cartridges produce only fractions of a millivolt, so reaching very high gain while keeping noise and distortion low and following the RIAA-IEC curve accurately is the central design task. Soulution keeps the signal path unbalanced to minimise the number of components, but builds the two channels as separate dual-mono circuits to prevent crosstalk. Relays switch the inputs, including their ground connections, and input buffering presents a benign load to the cartridge. Gain and loading are selectable independently for each input, and an IEC subsonic filter below 20Hz removes rumble from warped records that would otherwise drive woofers into large excursions; mono operation is also available. During a volume change, a programmable gain amplifier takes over briefly so level changes are smooth and free of switching clicks, then hands control back to the resistors. The output stage, identical to the 725's, uses special power transistors linearised by an analogue computing network, with a bandwidth of 40MHz. Separate power supplies feed the audio stages and the digital control circuits, and the audio supply is built like an amplifier's, with large storage capacitance.

Pairing

With its volume control and low output impedance, the 755 can drive power amplifiers such as Soulution's own directly through long balanced cables, or feed any line preamplifier at a fixed level. The multiple inputs allow multiple tonearms or turntables.

Alternatives

Soulution Audio's own 750 offers three MC inputs with lower maximum gain and only a simple 15dB level trim.