Усилители мощности моно — Nuprime Audio AMG One

The AMG One is a single-channel Class D power amplifier from NuPrime Audio, and stereo playback calls for a pair. NuPrime describes it as a scaled-down derivative of its larger Evolution monoblock, carrying over the same distortion-cancelling output topology in a half-width case, and NuPrime grants a two-year guarantee on it.

Key specs that matter

NuPrime rates continuous output at 170 W into 8 ohm and 220 W into 4 ohm, with peak figures of 210 W and 260 W for the same loads. Voltage gain is 21 times, or 26.44 dB, and 1.7 Vrms at the input brings the amp to rated power. Input impedance is 47k ohm and output impedance is 4 milliohm. THD+N is listed as 0.003% at 5 W, 0.004% at 50 W and 0.03% at 100 W, while signal-to-noise figures rise from 95 dB at 5 W to 105 dB at 50 W and 110 dB at 100 W. Bandwidth runs from 10 Hz to 50 kHz at the minus 3 dB points. The chassis is 55 mm high, 235 mm wide and 285 mm deep and weighs 4.5 kg. In standby it takes 0.4 W, and at idle it draws 8 W on 115 V mains or 7.5 W on 230 V.

Engineering and use context

NuPrime calls the circuit Only Distortion Cancellation, or ODC. The error signal is taken directly from the MOSFET output devices and the output filter, which lets the design run with a much smaller amount of negative feedback. The input stage and the Class D oscillator both use Nisshinbo MUSES8820 op-amps, and switching runs at 600 kHz. The supply is built around a 250 W toroidal transformer with 22,000 uF of filter capacitance, and wide copper PCB traces rather than internal wiring carry current from the supply to the amplifier board, with 15 A low-resistance terminals along the power path. A rear toggle chooses between RCA and XLR inputs, and NuPrime advises against connecting both at once. Trigger sockets for 12 V, one in and one out, let the amp power up in step with a preamp, a mains selector covers both supply voltages, and a 5 A slow-blow fuse protects the unit.

Pairing

The balanced XLR input and modest input sensitivity call for an upstream volume control, as found on a line preamp or a converter fitted with level control, and NuPrime lists its AMG DAC as a companion for this amplifier. With current delivery rising into 4 ohm and a very low output impedance, the AMG One is suited to floorstanding or stand-mounted loudspeakers of either common nominal impedance.

Alternatives

The NuPrime Evolution Two is the larger ODC monoblock, rated at 300 W and 600 W into the same two loads, with 48,400 uF of supply filter capacitors.