Усилители мощности стерео — Nuprime Audio AMG STA-SE

The AMG STA-SE is the Special Edition of NuPrime's AMG STA stereo power amplifier, part of the company's AMG series. It combines a single-ended Class A input module with a Class D output stage, and the SE revision upgrades the switching stage, feedback resistors and power supply of the original STA. NuPrime also offers existing AMG STA owners an upgrade to SE specification through its distributors.

Key specs that matter

Output is 130 W per channel into 8 ohms and 200 W into 4 ohms in stereo, and bridging yields a 300 W mono amplifier. Input sensitivity is 1.2 V, gain is 26 dB and input impedance is 1 Mohm on balanced and single-ended inputs. Output impedance is 0.02 ohm. Frequency response runs from 10 Hz to 50 kHz, signal-to-noise is 100 dB and THD+N is 0.006%. The chassis measures 235 x 55 x 300 mm and weighs 4.5 kg.

Engineering and use context

The input module is single-ended Class A without negative feedback, and the output stage is a double-feedback Class D design switching at 700 to 750 kHz, a high frequency that places switching residue further above the audio band. In the SE version the Class D circuit runs its MOSFETs 30% cooler at these speeds. Precision resistors with a tolerance of 0.1% and a temperature coefficient of 15 ppm are used in the feedback sampling, so the feedback stays stable as the chassis warms. A retuned secondary feedback loop is added. Larger supply capacitors and low-impedance routing raise instantaneous current to 1.5 times that of the original AMG STA. A small switch-mode supply powers the low-voltage circuits, while a large linear supply feeds the Class D stage. The PCB integrates ground shielding against external interference. The front panel is CNC-milled from 15 mm aluminium alloy, and the slim chassis runs cool enough to sit on a shelf without large heatsinks. Balanced XLR and RCA inputs are both provided.

Pairing

The high input impedance suits valve preamplifiers with high output impedance as well as solid-state designs, and the input sensitivity matches most line outputs. In stereo it drives most bookshelf and floorstanding speakers, and two units bridged as monoblocks suit harder loads. The AMG PRA preamplifier stacks directly on top. Its small footprint lets it sit next to a streamer or DAC on a single shelf, and the balanced input suits sources placed some distance from the amplifier.

Alternatives

NuPrime's STA-9 is a smaller half-width stereo power amplifier.