Усилители мощности стерео — Soulution Audio 312 stereo amplifier

Within the 3 Series, the 312 handles stereo power amplification for Soulution - the audio brand of Spemot AG in Dulliken, Switzerland. It sits below the 511 of the 5 Series and the 717 of the 7 Series, and it replaced an earlier 3 Series model with larger power reserves. The amplifier circuit borrows its technology from the Series 5 amplifiers. In Italy the 312 was priced at EUR 23,400.

Key specs that matter

The 312 is rated at 100 W into 8 ohm, 200 W into 4 ohm and 400 W into 2 ohm for bursts shorter than 5 seconds. Peak output current reaches 30 A. Gain is +26 dB, input sensitivity is 1.55 Vrms and the single balanced XLR input presents 2 kOhm. Bandwidth runs from DC to 800 kHz at -3 dB, phase shift at 20 kHz stays under 3 degrees, THD is below 0.0004 percent and input-related spot noise is under -140 dBV per root hertz. The damping factor exceeds 5,000. Idle draw is 110 W, nominal consumption 1,200 W and standby below 0.5 W. The casework measures 430 x 490 x 142 mm and weighs about 17 kg.

Engineering and use context

The voltage stage relies on linearised amplifiers with a cut-off frequency of 80 MHz, and current amplification is split across three stages, each held to a narrow, almost linear operating range. Four switched-mode power modules with multistage filter networks feed the circuit, rated at 1,200 VA continuous and up to 4,200 VA for more than 5 seconds. They sit physically apart from the amplifier boards behind shielding to keep noise out. The whole chassis works as a heat sink, so it must not be covered, and ambient temperature must not exceed 40 degrees C. There is no mains switch, so the unit enters standby once connected. Protection mutes the outputs when current above 30 A is detected and powers down on excessive DC offset or high-frequency oscillation, with error codes shown per channel on the front display. Its feet contain a constrained layer damping system, and shims are supplied for uneven shelves. Firmware is updated from a USB stick, and an IR remote comes in the box.

Pairing

With only a balanced input, the 312 has to be driven from a balanced preamplifier output, and the 326 from the 3 Series is its matching control unit. The two Link jacks allow remote power-up from a partnering Soulution unit, and a menu setting lets the amplifier wait for that Link signal, start from its button or switch on as soon as mains is present. Speaker cables attach to one pair of binding posts per channel, and the rising output into 2 ohm suits low-impedance designs.

Alternatives

The Soulution 511 is the stereo power amplifier from the 5 Series, rated at 150 W into 8 ohm and 300 W into 4 ohm in stereo mode and switchable to mono operation.