It hit me not long ago: I need more Mac in my life! I promptly purchased the current production version of McIntosh Laboratory’s time-honored MC275 tubed amplifier, to mate to the Mac C2300 tubed preamplifier I already owned. The recently reinvigorated debate in these pages comparing solid-state and single-ended tube designs got me to thinking. One thing led to another, and voilà! McIntosh’s latest solid-state stereo amplifier, the MC462 Quad Balanced ($9000), arrived, bolted to a shipping pallet and encased in two big, heavy, nested boxes. All that packaging weighs 33 lb—the amp inside weighs 115 lb. If you want to lift it onto a rack, you’ll need two people, a serious handcart, and a strong, deep shelf.
Frank McIntosh and his company got off to a very strong start in 1949, in Silver Spring, Maryland, with their first product, the tubed Unity Coupled 50W1 Power Amplifier. A patent was granted that same year for the Unity Coupled circuit and transformer. In 1951, McIntosh Laboratory moved to Binghamton, New York, where they’ve been ever since.
A week after the MC462’s arrival I saw for myself, on a guided tour of the plant, how it all comes together.1 I could feel McIntosh’s conservative approach: doing the maximum, not the minimum, at all stages of design and manufacturing, to maintain a high level of quality.
What are you?
The solid-state MC462 power amplifier replaces the MC452 and is now the most powerful stereo amplifier McIntosh offers, with a specified continuous power output of 450Wpc into 2, 4, or 8 ohms, and peak output current of 75 amperes per channel. (McIntosh claims a 66% increase in dynamic headroom over the MC452, achieved by a big increase in power-supply filter capacitance.) The MC462’s distortion is specified as not exceeding 0.005% at rated power output, and as no more than 0.002% in the mid-frequencies.
In the MC462, which operates in class-AB, the concept of complementary pairs is taken to an extreme. In most push-pull amps, the two phases of the signal waveform are amplified separately by two single-ended amplifiers, the outputs of which are then combined to recreate the waveform in full—and in the combining, some distortion products are cancelled out. What McIntosh has created is a push-pull amp in which each phase of the signal waveform is itself amplified by a push-pull output section: There are two complete push-pull amplifiers in each channel, their outputs combined in what McIntosh refers to as a Quad Balanced architecture.
The design element that allows McIntosh to do this has been a technical cornerstone of all their solid-state amps: a single-winding transformer called an autotransformer—or, in the trade lingo arguably coined by McIntosh, an Autoformer. Beginning in 1967 with their first transistor amp, the MC2505, McIntosh has used output-stage Autoformers to optimize impedance matching between output devices and loudspeaker loads, as well as to protect the latter from DC. Fifty-two years later, an output-stage Autoformer allows the company to combine the outputs of multiple push-pull amps in a manner that, they say, has unprecedented distortion-cancelling capabilities. (This is also how the MC462 can deliver the same 450Wpc output to its pairs of 2, 4, or 8 ohm speaker taps.)
All of this firepower ran amazingly cool—when I laid a hand on the top panel, it was barely warm. This cool running is in part achieved through what McIntosh describes as their current-generation ThermalTrak Power Transistors; the MC462’s power output circuit monitors their temperature and adjusts bias accordingly. Another reason is the extensive, heavy-duty heatsinking built into the rear half of the MC462. These include a nice touch: the initials MC are formed by the sinks’ vertical fins and are visible from above—as if you’re standing atop a subway grille on a Manhattan street. Also visible from that vantage is evidence of McIntosh’s pride in the MC462’s lineage: circuit block diagrams handsomely adorn the top plate.
At 17.5″ wide by 9.45″ high by 22.5″ deep, the MC462 occupies an impressive amount of real estate, but finding room for it wasn’t as hard as I at first thought—that 22.5″ depth includes the two hefty handles on the faceplate and the rear deck on which the speaker terminals are vertically arrayed, and the amp’s four rubber feet are sensibly separated by only 12.5″ from front to back. The black glass faceplate proudly displays two large meters backlit in McIntosh blue, each about 5.5″ wide by 2.5″ high. The meters’ upper scale is calibrated in watts, to indicate the MC462’s output: the large numbers top out at 450, and after that, in smaller numbers, come “900” and “1.8k,” referring to the amp’s dynamic headroom: brief bursts of wattage beyond the MC462’s rated continuous output. The MC462’s specified dynamic headroom is 3dB—in the real world, that’s a lot. The meters’ lower row of figures calibrates the amp’s output in decibels, from –50 to 0.
The rest of the front panel is minimalist. There are a green-lit “Olde English” McIntosh logo and three small red LEDs: one indicates Standby status, and the other two tell you when the Power Guard circuit kicks in. There are only two control knobs: the one at left, labeled Meter, turns the meters’ Lights Off if desired; the Watts setting shows you real-time meter readings, while Hold lets the needles linger on peak output levels before slowly resuming action. The other knob, Power, has positions for Off, On, and Remote, the last for connecting to a McIntosh preamp for power-up/down sequencing.
The rear end of the MC462 is straightforward. In addition to the six pairs of speaker output taps sticking straight up from the shallow rear deck are AC in, a fuse bay, and, jutting out horizontally from the rear panel, pairs of balanced and unbalanced inputs and outputs. One small switch lets you select between balanced and unbalanced operation, and with another you can enable or disable the Auto Off function, which shuts down the MC462 after it hasn’t sensed an input signal for 30 minutes. I particularly liked McIntosh’s patented gold-plated speaker binding posts. Each has two moving parts, which you first tighten with your fingers, then tighten a further quarter-turn with a small wrench (supplied), for a snug connection.
System and setup
Not wanting to face too many variables, and to give the MC462 enough time to break in, I spent my first days with my system unchanged, listening to my Harbeth 30.2 40th Anniversary Edition loudspeakers, which Herb Reichert reviewed in April 2018. Central upstate New York, where I live, benefits from ample clean power, but kicking that power’s quality up a big notch is my AudioQuest Niagara 7000 power-line conditioner.
What first caught my ear when I cranked up the MC462 was nothing—no noise of any kind through the speakers or directly from the amp itself. Control of mechanical and circuit noise seems to be a real strength of McIntosh products—I’d had a similar experience when introducing the McIntosh MC275 amp into my rig. The two amplifiers in my reference system that had preceded the MC275, a solid-state and a single-ended tube design, each produced some level of hum, as well as noise through my speakers, that I could never eliminate. But the MC462 provided those impressive backgrounds of “black” silence deeply desired by audiophiles—they really do play a role in the appreciation of microscopic and macroscopic differences in levels of detail and dynamics of recorded music.
The music goes ’round and ’round . . .
We all have our default settings. Each February, for Stereophile‘s annual “Records to Die For” feature, I could happily pick Shirley Horn’s Here’s to Life (CD, Verve 314 511 879-2). Every time, it’s the first recording I reach for when I want to hear wussup in my system.
I cued up “Return to Paradise.” Hearing music from the MC462 for the first time, I thought of visual metaphors. I thought of turning the contrast setting up or down on a television, or adjusting the amount of color saturation. Zooming in and out also has its audio analogs. The audio picture—the soundstage width and depth—enlarged in all parameters, and the colors seemed deeper. I heard a kind of fleshing out of Horn’s voice, her deep mezzo gaining heft and impact. The other aspect that grabbed me was the percussion in this track, which is complex and subtle, capable of revealing a system’s ability to resolve minute details. I heard intricate percussion sounds that I didn’t recall having heard before, and the drum kit also had more impact, with more swing.