Усилители мощности моно — PS Audio M700 Amplifier

The M700 is a mono power amplifier from PS Audio's Stellar line, the Boulder, Colorado company founded in 1973 by Paul McGowan. It is the most powerful model in the Stellar range and is sold in pairs, combining a Class A input stage with a Class D output stage in a slim chassis that PS Audio designs to be stacked two high.

Key specs that matter

Output is 350 W into 8 ohms and 700 W into 4 ohms, and the amplifier is stable into 2 ohms for short transients. Voltage gain is 30.5 dB and input sensitivity for rated output is 1.01 V. Input impedance is 100 kohm balanced and 50 kohm unbalanced. Output impedance is below 0.007 ohm at 50 Hz, giving a damping factor above 1100 into 8 ohms and above 550 into 4 ohms. Response is 10 Hz to 20 kHz within 0.5 dB and 10 Hz to 50 kHz (+0.1/-3 dB). THD is below 0.1% from 20 Hz to 20 kHz at rated power and below 0.02% at 1 W into 4 ohms, and noise at 300 W is lower than -100 dB. Each chassis measures 432 x 76 x 305 mm and weighs 5.9 kg.

Engineering and use context

The input stage is PS Audio's Analog Cell, a fully differential, discrete Class A MOSFET circuit with zero feedback. It receives the signal from the preamplifier or DAC and prepares it for the output stage. Current is supplied by a Class D output stage based on the ICEpower 700AS1 module from the Bang & Olufsen subsidiary, which provides high efficiency and very low heat. Putting each channel in its own chassis removes crosstalk and gives each channel its own power supply. The approach recalls PS Audio's HCA-2 of the early 2000s, which also paired a Class A input with a Class D output. Inputs are RCA and true balanced XLR, and each unit has two pairs of copper-based nickel-plated binding posts, a front-panel standby switch and a DC trigger input. Black and silver finishes are offered. Mains voltage is set at the factory for 100, 120 or 230 V, and the warranty runs three years.

Pairing

The M700 reaches full power from any preamplifier or DAC with a variable output. The very low output impedance and 2 ohm stability suit low-sensitivity speakers and designs with difficult impedance dips, while its power reserve leaves ample headroom for large rooms. PS Audio's Stellar Gain Cell DAC or a DirectStream DAC with volume control can feed it directly.

Alternatives

PS Audio's Stellar S300 packs the same Analog Cell and Class D approach into a stereo chassis with 140 W per channel.