70 years in the making, the new MC901 is the ‘ultimate solution’ for bi-amping loudspeakers: a 300-watt valve amplifier for midrange and treble, plus a 600-watt solid-state amp for bass, all in one chassis!

McIntosh has announced the MC901 Dual Mono Amplifier. Drawing on the company’s 70-year experience of producing valve amplifiers (since the 1940s; solid-state amplifiers since the 1960s), the MC901 has been uniquely designed as, say McIntosh, “the ultimate solution for bi-amping high-performance loudspeakers”.

Two In One Design

The MC901 is two amplifiers in one, each offering a differing design philosophy: a 300-watt valve amplifier is attached to a 600-watt solid-state amplifier on one unified chassis. The valve section effectively drives the loudspeaker’s mid and upper drive units using eight KT88 output tubes, four 12AT7 and two 12AX7A signal tubes; the solid-state section delivers its 600 watts directly to the bass drivers.

Unity Coupled Circuit

The MC901’s valve amp section uses McIntosh’s 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 of impedance; similarly, the solid-state section delivers its full 600 watts using McIntosh’s Autoformer™ technology.

Valve & Solid State

The valve and solid-state 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. Prior to the MC901, bi-amping a speaker required two separate amplifiers. It could also require an external crossover (along with a lot of trial and error) to properly configure the two amps. The MC901 solves this issue thanks to its internal adjustable crossover with the controls (easily accessible on the top of the unit) allowing the user to optimise performance. Relative gain levels for each amplifier section can be adjusted from -6dB to + 3dB and a direct feed can also be connected to each amplifier section, thus bypassing the filters.

McIntosh Blue

Like virtually all McIntosh amplifiers, the MC901 features an iconic ‘McIntosh Blue’ Watt-meter, which, like the MC901 itself, is a new design; so too is its meter following the recent introduction of McIntosh’s new DualView™ Power Output Meter. The DualView design features two of McIntosh’s traditional, fast-responding mechanical meters stacked above and below each other in a single meter window; one meter is dedicated to the valve amp and the other to the solid-state amp. Each meter operates independently of the other and displays the real-time power reading of each amplifier section.

Power Guard Screen Grid Sensor

A brand-new technology in the valve amplifier section of the MC901 is Power Guard Screen Grid Sensor™ (SGS). Power Guard SGS™ helps prevent premature valve failure by monitoring the screen grid current in the KT88 output valves. If the current becomes too high, a circuit in Power Guard SGS is activated which then dynamically attenuates the input signal in real-time to keep the valves operating at safe levels.

Although an entirely new design, the MC901 comes with the technology one would expect from a McIntosh amplifier: Power Guard® (in the solid-state amplifier section), Sentry Monitor™, Quad Balanced design, Power Control, Solid Cinch™ speaker binding posts, McIntosh Monogrammed Heatsinks™, plus McIntosh’s eco-friendly Power Management System.

McIntosh Design

The MC901 is bestowed with many signature McIntosh design cues. The top is highlighted by a series of diagrams printed on glass that outline the basic circuitry and specifications of the unit, along with a glass nameplate trimmed with a circular aluminium ring that’s finished to match the front panel end-caps. The sides are adorned with vintage McIntosh-styled die-cast aluminium name badges. Two classic McIntosh knobs are located on the front of the polished stainless-steel chassis and direct LED back-lighting illuminates the DualView meter, McIntosh logo and the lettering on the black glass front panel.

Pricing And Availability

Shipping is expected to begin in January 2020 in the UK £39,995 per pair; December 2019 in the USA $17,500 USD each.

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