Усилители мощности стерео — McIntosh MC255

The McIntosh MC255 is a five-channel solid state power amplifier for home theatre use and a five-channel counterpart to the seven-channel MC257. It was announced with a UK price of GBP 9,995, with shipping expected toward the end of 2019. Compared with the previous generation, the front three channels gained 25% more power.

Key specs that matter

The three front channels deliver 250 W each into 4 or 8 ohms, and with all five channels driven every channel produces 200 W. Distortion is 0.005%, signal-to-noise ratio is 108 dB and frequency response stays within +0 and -0.25 dB from 20 Hz to 20 kHz. Dynamic headroom reaches 3.6 dB, up from 1.7 dB, after filter capacitance was increased by 50%. Damping factor is above 70 at 4 ohms and above 140 at 8 ohms. The chassis measures 445 mm wide, 239 mm high and 533 mm deep, and the amplifier weighs 40.6 kg, or 55.6 kg packed.

Engineering and use context

All channels share a push-pull complementary transistor circuit with direct coupled outputs and the McIntosh Dynamic Power Manager, which lets each channel give its full rating whether 4 or 8 ohm speakers are connected. The amplifier has no fan. Heat is carried away by convection through four Monogrammed Heatsinks with more than 1.8 m2 of area, attached to high-current output transistors, and power comes from a specially wound toroidal isolation transformer. Power Guard and Sentry Monitor protect against clipping and short circuits. A TripleView power output meter groups three mechanical meters in one enclosure to show the three front channels, with direct LED backlighting on the front panel and knobs for meter lights and power.

Pairing

Five balanced inputs are fitted, with unbalanced connection also supported, so the MC255 can take the multichannel outputs of an AV processor over either cable type. Speakers attach to gold-plated binding posts, and a rear LOAD switch sets the speaker impedance. Remote power control can be set for five channels or a 3+2 split, which allows two channels to be run separately from the front three, and an eco-friendly power management system keeps standby draw below 0.5 W. The remote power control jacks include a delayed output for switching further units in sequence. The mains supply is rated at 15 A on 120 V and 6.5 A on 240 V.

Alternatives

The McIntosh MC257 is the seven-channel home theatre amplifier from the same generation.