IT’S almost the end of the year, and most people are already holidaying or about to… but not those busy bees at McIntosh Labs who’ve come up with something special to wrap up another eventful 12 months. This is the MC901 dual mono amplifier, which McIntosh says is a “one-of-a-kind, ultimate solution” for those wanting to bi-amp their loudspeakers.
“The MC901 is a monoblock amplifier that drives a single speaker. But it is unlike any other monoblock amplifier. What makes the MC901 so unique is that it is two amplifiers combined into one. Adding to the uniqueness is that each amplifier is of differing design philosophies: the MC901 consists of a 300-watt vacuum tube amplifier attached to a 600-watt solid-state amplifier on one unified chassis,” says the McIntosh literature.

The valve amp section is meant to power the speaker’s mid and upper drivers; it is loaded with eight KT88 output tubes, and four 12AT7 and two 12AX7A signal tubes. The solid-state section delivers its massive wattage muscle into the power-hungry woofers.
“The vacuum tube amp in the MC901 uses our patented Unity Coupled Circuit output transformer – the same technology McIntosh was founded on in 1949 – to deliver its full 300 watts into almost any speaker regardless if it has two, four or eight-ohm impedance. Similarly, the solid state amp delivers its full 600 watts into a two, four or eight-ohm impedance speaker via our Autoformer technology.”

One has every right to wonder why McIntosh designed something like the MC901, and here’s the answer.
“Vacuum tubes do not perform at their best when they are amplifying lower frequencies that are not being used by the loudspeaker. With the MC901, the vacuum tube amp will not be burdened with low-end reproduction as the solid-state section will drive these frequencies.
“The two amplifier sections of the MC901 are designed to work together in a synergistic relationship and are specifically engineered to assure that each section only amplifies its intended frequencies. Each amplifier section has its own discrete power supply so neither siphons power or performance away from the other. All of this results in easy bi-amping with unparalleled performance and sound reproduction from your speakers.”

Also, McIntosh wanted to make bi-amping hassle-free for the user.
“Prior to the MC901, bi-amping a speaker required two separate amplifiers. It also required an external crossover, along with a lot of trial and error, to properly configure the two detached amplifiers so they worked together as best as possible.
“The MC901 solves this issue thanks to its internal, adjustable crossover with the controls easily accessible on the top of the unit. These adjustable crossover filters allow you to optimise the performance of both amplifier sections to your listening preferences. Relative gain levels for each amplifier section can be adjusted from -6dB to + 3dB. A direct feed can also be connected to each amplifier section, thus bypassing the filters.”
The 77kg MC901 begins shipping this month, and will retail at US$17,500.
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