Усилители мощности стерео — SOtM sPA-1000

The sPA-1000 is a stereo power amplifier in the Ultimate range of SOtM, a Korean company better known for music servers, USB cards and linear power supplies. Instead of buying a ready-made switching module SOtM designed its own Class D output stage for this model. It sells for GBP 3,705 in the United Kingdom and AUD 5,500 in Australia.

Key specs that matter

Two channels, each in bridge-tied-load form, deliver 200 W per channel into 4 ohm. Frequency response runs from 20 Hz to 40 kHz, and THD+N is quoted as 0.05% at 1 W into 8 ohm. There is one unbalanced RCA input, accepting up to 2 Vrms, and one balanced XLR input, both with an input impedance above 10 kohm. A 3.5 mm trigger in and out handles 12 V at up to 0.2 A. Mains supply is 220 to 240 V or 100 to 120 V at 50 or 60 Hz, drawing 3 A or 6 A. The chassis measures 360 x 84 x 255 mm and the weight is 7.5 kg or a little more.

Engineering and use context

The circuit stays fully balanced from the input stage through to the speaker terminals, which SOtM uses to reject noise generated both inside the case and from outside. Closed loop control around the output stage keeps distortion low, and a fourth-order low-pass filter after the switching stage flattens the frequency response. The company also developed what it calls pumping reducer technology - a power stabilisation circuit that suppresses the power pumping effect, meaning fluctuations of the supply voltage while music is playing. Energy comes from a high-current toroidal transformer, and the amplifier is protected against output short circuits and overheating. On the front there is a single operating LED and a standby button, with the AC power switch on the rear panel. SOtM rates operation between 10 and 30 degrees C and storage between 0 and 40 degrees C, at 10 to 90% humidity.

Pairing

The input sensitivity and impedance suit any line-level preamplifier or a DAC with a volume control, because the front panel carries no level knob and gain must be set upstream. Low-impedance speakers are covered by the power rating, while SOtM publishes no separate figure for higher-impedance designs. The trigger link lets the amplifier wake together with a preamp or streamer that has a matching trigger output. The chassis width matches the SOtM sMS-1000SQ server and sPS-1000 supply for a stacked system.

Alternatives

SOtM offers no other stereo power amplifier, so the sPA-1000 is the only model of this type in the catalogue.