McIntosh MC501 monoblock power amplifier Page 2

McIntosh's Power Guard circuit, a waveform comparator, monitors input and output waveforms. When the amp is overdriven, the Power Guard notices any difference in the two waveforms that exceeds 0.3% harmonic distortion, and engages a dynamic attenuator at the amp's input to reduce the signal just enough to prevent any further distortion reaching the amp. This is not limited to the amp's rated output power; the manual states that the MC501 will actually produce distortion-free output well above its rated power (footnote 4).

Unwrapping and getting comfortable
McIntosh's packaging is the best I've seen for electronics short of the custom-made Anvil-style cases provided by Halcro and Lamm's massive wooden crates. Each MC501 is bolted to a wooden plinth and a thick foam pad, then surrounded by foam packing within multiple heavy cardboard boxes. Even UPS might not be able to bang up one of these amps. The instruction manual is exemplary—it's easy to understand, and even includes welcome instructions on how to re-pack the brutes. Brutes they are: each MC501 weighs a truss-busting 105.5 lbs in its box and a barely more manageable 92 lbs out of it.

Styling is a smoothly modern update that remains true to Mac tradition: these amps look like something Bryan Ferry might own. A sleek front panel of black glass carries that gorgeous, remarkably informative power meter and two switches, one for On/Off/Remote turn-on, and one that turns off the meter's lights and selects its function—peak hold or real-time readout of watts. The switch legends and traditional McIntosh logo glow an almost tropical green, while the meter is illuminated in soft blue. Very sexy.

Around back are some large heatsinks and, at the top rearmost edge of the chassis, an AC power input, fuse, excellent-quality XLR (pin 2 hot) and RCA jacks, a selector to switch between inputs, and sockets for remote turn-on connections. The package is completed with three massive sets of WBT binding posts (they look identical to those used on the Nova Utopia speakers) for the Autoformer's 8, 4, and 2 ohm outputs.

The '501s were settled atop the usual Grand Prix Audio Monaco amplifier stands, and I used Siltech SPX-30 Classic power cables for the first part of auditioning. Some interesting things happened when Shunyata's Hydra 2 power conditioners arrived, with a matching set of Anaconda and Anaconda Vx power cables to run from wall to Hydra 2 to Mac (see Sidebar, "Shunyata Research Power Products"). Siltech SQ-110 Classic and Acoustic Zen Silver Reference interconnects saw principal duty, with Nordost Valhalla and Siltech LS-188 Classic speaker cables. During my time with them, the MC501s showed all the diva temperament and high-maintenance character of a pair of manhole covers—exactly what you'd expect from a Mac.

Much to my surprise, the '501s required surprisingly little break-in time, their performance changing barely at all within the first 100 hours or so. The only detectable changes of significance were that the overall dynamic response became a little more open across the spectrum, and the whole presentation sounded a bit more relaxed. This was a wonderful change from the usual lengthy break-in procedure required with a big solid-state amplifier.

A couple of other seldom-acknowledged facts: I gather that McIntosh products hold their value better than any others in the business. That the company has been around for 55 years is hugely reassuring, and their matchless reputation for reliability and standing behind their products has been earned over time for good reason.

Rekindling the flame
Right from the get-go, the MC501s showed their basic character. From first listen, they exhibited sound that was totally relaxed yet completely controlled. They could easily manage mighty peaks with no apparent effort, and had superb bass control. The Nova Utopias demand an iron fist in a velvet glove for best sound below 60Hz, and the Macs handled those large ported woofers with ease.

The '501s' bass was something different from the norm of powerful solid-state amps. As John Atkinson observed on hearing the Macs in my system, they define the leading edge of bass transients in an especially lifelike way: to the ear, the transients of bass instruments are seemingly slower but no less precise than those of upper-midrange and treble instruments. The Macs perfectly captured this quality.

An industry friend burned me a copy of a demo disc he uses at shows, and one of the most impressive tracks on it is Eleanor McAvoy's "I've Got You to See Me Through," from her Yola CD (Market Square 113). Apart from being one of the finest grownup love songs I've heard in ages, it's exquisitely recorded, and the five-string bass guitar was fabulously convincing. Through the Macs, the bass rolled into the room—it didn't jump or snap into the space as if it were gated. Bass guitar should sound exactly so when played with the fingers rather than a pick. On the McAvoy track, it bloomed beautifully and was sensationally convincing, not to mention deep—the low C set loose objects abuzz in my room.

Listening to Steve Swallow's beautiful playing on the title track of Carla Bley's Nite-glo (LP, WATT 16) was very illuminating. Swallow plays with a heavily worn brass pick, and the minute scrape of the pick against the bass's strings was still there, though less highlighted and more of a piece with each note than with most other amps, particularly solid-state ones. The tautly drawn, relentlessly pulsing synth bass on Majestic 12's remix of Kelis' "Milkshake," from Ultra.Trance:3 (CD, Ultra UL1180-2), was waaay too cool on the Macs—one of the few things I've ever heard that actually made me want to get up and do the goofy-white-guy funky chicken.

Footnote 4: I shudder to think what kind of volume levels or catastrophic malfunction would be necessary to trigger the Power Guard. With the Focal-JMlab Nova Utopia Be loudspeakers, the meters seldom registered over 150W or so on peaks of immensely powerful music played at Stupid-Approved levels, and the MC501s' heatsinks never became more than slightly warm.—Paul Bolin
2 Chambers Street
Binghamton, NY 13903-2699
(607) 723-3512