Power amplifiers stereo — McIntosh MC152

The MC152 is a stereo solid-state McIntosh amp built in a 15.2 cm tall chassis so it fits spaces where the larger McIntosh amplifiers do not. It is the lowest-power stereo model in the current solid-state range, below the MC312 and MC462, and McIntosh positions it for modestly sized systems or for driving the surround channels of a home theater.

Key specs that matter

With both channels driven, the MC152 produces 150 W per channel into 2, 4 or 8 ohm. Total harmonic distortion is 0.005% maximum at any level from 250 mW to rated power between 20 Hz and 20 kHz, and intermodulation distortion is also 0.005%. Dynamic headroom is 2 dB. Response is +0, -0.25 dB from 20 Hz to 20 kHz and +0, -3 dB from 10 Hz to 100 kHz. Signal-to-noise is 118 dB below rated output via the balanced input and 115 dB via the unbalanced one. Full output needs 2.4 V balanced or 1.2 V unbalanced, input impedance is 22 kohm on both, and voltage gain runs from 23 dB on the 2 ohm tap to 29 dB on the 8 ohm tap. The damping factor exceeds 40 across the band. The unit is 44.5 cm wide and weighs 34 kg.

Engineering and use context

The push-pull complementary output stage uses ThermalTrak output transistors, which McIntosh chose for lower distortion and cool running. Each channel feeds the speaker through an Autoformer, the McIntosh output transformer that matches the amplifier to each speaker tap and also protects the speaker from DC. Power Guard holds distortion below 2% even with a 14 dB overdrive, Sentry Monitor protects the output stage, and thermal circuits guard against overheating. A large power transformer and capacitor bank keep the supply stable when mains voltage varies. Two blue peak-responding watt meters sit behind the black glass front with silver end caps, and their lighting can be switched by a McIntosh preamplifier through the control jack. An Auto Off feature turns the amplifier off about 30 minutes after the input signal stops. Each unit is built for one mains voltage between 100 and 240 V, draws 3.7 A at 120 V and uses under 0.3 W in standby.

Pairing

Because the rated power holds into the lowest-impedance tap, the MC152 accepts speakers with difficult impedance curves. The balanced XLR input offers the better noise figure with a preamplifier that has XLR outputs, and the 12 V power control link starts the amplifier together with McIntosh preamplifiers and A/V control centers.

Alternatives

The McIntosh MC312 is the next solid-state stereo model up, rated at 300 W per channel.