Фонокорректоры — Soulution Audio 350 phono stage

The 350 phono stage is a moving-coil phono preamplifier in the Series 3 range of Soulution, made by Spemot AG, a company based in Dulliken in Switzerland. The unit has a single unbalanced MC input and feeds a line stage or integrated amplifier through balanced and unbalanced outputs, and an IR remote control is supplied with it.

Key specs that matter

Termination impedance for the MC input can be set between 20 and 1,260 ohms. Gain is +66 dB at the balanced output and +60 dB at the unbalanced one. Frequency response runs from DC to 2 MHz, and deviation from the RIAA curve stays under plus or minus 0.2 dB between 20 Hz and 20 kHz. THD is below 0.001 percent, while spot noise referred to the input stays below -160 dBV/√Hz. Output impedance is 10 ohms balanced and 5 ohms unbalanced, with a peak output current of 0.2 A. Nominal consumption is 60 W, with less than 0.5 W drawn in standby, and the maker lists models for 100-240 V and for 220 V at 60 Hz. The chassis measures 430 x 350 x 142 mm and weighs about 10 kg.

Engineering and use context

A switched mode power supply followed by fast-switching DC-DC converters and low noise linear regulators provides the internal supply voltages. RIAA equalisation is handled by a two stage active and passive design, with tight tolerance passive parts setting the time constants. Three wide bandwidth, low noise amplifier stages produce the gain, and the output stage itself has a bandwidth above 5 MHz at -3 dB. A high-pass filter to the RIAA-IEC standard, -3 dB at 20 Hz, can be switched in through the PHONO-HP menu. Loading is changed from the front panel rotary knob or from the remote, and the display shows the chosen impedance and filter state. The unit monitors all supply voltages and mutes itself with an error code if one fails. The whole chassis acts as a heat sink, and the feet use a constrained layer damping system, with shims supplied for levelling. There is no mains switch, and the rear USB socket serves only to load new firmware.

Pairing

The turntable earth lead goes to a dedicated rear grounding post. The Link-Com socket lets another Soulution component power the 350 up remotely, and a power-mode setting can make it wait for that link signal or start as soon as mains voltage is present. According to Soulution, even long connecting cables to an amplifier are no problem for the output stage, and the manual suggests balanced cables for longer runs.

Alternatives

Soulution also offers the 550 phono in its Series 5 range.