McIntosh MC901 Dual Mono Amplifier Combines Philosophies

Check out historic events like presidential inaugurations and even concerts like Woodstock, and you’ll probably find a McIntosh amplifier. They’ve also been integral parts of iconic sound systems like the Grateful Dead’s Wall of Sound and Despacio. Since the 1940s, McIntosh has been making vacuum tube amplifiers. Solid state amplifiers are a bit newer, starting in the 1960s, and now, with 2020 right around the corner, McIntosh is adding to their history with the MC901 Dual Mono Amplifier.

McIntosh Dual Mono Amplifier without cover

For the MC901, McIntosh combined two amplifiers with different philosophies into one monoblock amplifier. The MC01 uses a 300 Watt vacuum tube amplifier that is attached to a 600 Watt solid state amplifier all on one unified chassis. For the speaker’s mid and upper drivers, the MC901 uses the 300 Watt vacuum tube portion through a set of eight KT88 output tubes with an additional four 12AT7 and two 12AX7A signal tubes. This section of the amplifier makes use of the same technology that McIntosh has been employing since the 1940s—the McIntosh Unity Couple Circuit output transformer.

McIntosh Dual Mono Amplifier top view

The 600 Watt amp comes in for the woofers. Vacuum tubes struggle with amplifying lower frequencies that the speaker isn’t using. With the solid-state amplifier taking on this responsibility, the sound comes out at a higher quality. This section delivers power into 2, 4, or 8 Ohm impedance speakers with McIntosh’s Autoformer technology. Both sections of the amplifier have their own power supply, which helps them to not interfere with each other. With this setup, you should be able to bi-amp with greater ease.

McIntosh Dual Mono Amplifier

Adding the final touches to the amp is the McIntosh Blue Watt meter. You’ll also find a new DualView Power Output Meter that displays two meters—one for the 300 Watt and the other for the 600 Watt—in one window. McIntosh also innovated what they are calling the Power Guard Screen Grid Sensor, which, according to McIntosh, helps to prevent premature tube failure by monitoring the screen grid current in the KT88 tubes.

McIntosh Dual Monoblock Amplifier

The McIntosh MC901 Dual Mono Amplifier is available through select vendors and is priced at $17,500. To set up a stereo system, however, you’ll need two, so your final bill will be around $35,000.

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