A Stunning Sound Experience

The MC451 Dual Mono Amplifier joins the MC901 in offering the ultimate solution to bi-amping a loudspeaker. Like the MC901, the MC451 uses McIntosh’s Hybrid Drive™ technology that combines a separate vacuum tube and solid-state amplifier onto one single chassis to produce the best possible sound performance from a bi-ampable speaker. Unlike the larger MC901, the MC451 has a more conventional McIntosh form factor and size, allowing it to fit into home audio systems, racks, and furniture more easily. Adding a pair of MC451s to your stereo system will allow your prized speakers to perform like never before.

Features

• Hybrid Drive™ Technology
• Designed With Bi-Amping Loudspeakers in Mind
• 150 Watt Vacuum Tube Amplifier With 300 Watt Solid State Amplifier
• Vacuum Tube Section Powers Mid and Upper Drivers
• Solid State Section Drives Power-Hungry Woofers
• DualView™ Power Output Meter

Power

The MC451 is comprised of a 150 Watt vacuum tube amplifier and a 300 Watt solid state amplifier, which is more than enough power to drive virtually all speakers. The vacuum tube section drives the speaker's midranges and tweeters, while the solid state section drives the woofers. The 150 Watt vacuum tube amplifier is powered by four KT88 output tubes which are located under a removable wire cage, plus two 12AT7 and one 12AX7A signal tubes; it uses McIntosh’s patented Unity Coupled Circuit output transformer to deliver its full 150 Watts into almost any speaker regardless if it has 2, 4 or 8 Ohm impedance. Similarly, the 300 Watt solid state amplifier delivers its full 300 Watts into a 2, 4 or 8 Ohm impedance speaker via McIntosh’s Autoformer™ technology. The two amplifiers in the MC451 are designed to work together in a synergistic relationship and are specifically engineered to assure that each only amplifies its intended frequencies. The large but quiet toroidal transformer generates enough power so that neither amplifier robs power or performance from the other. All of this results in easy bi-amping with unparalleled performance and sound reproduction from your speakers.

Bi-Amp

Bi-amping your speakers with the MC451 is easy. No longer do you need fiddle with two separate amplifiers, an external crossover, and a lot of trial and error to properly configure the two separate amplifiers with often times only so-so results. The MC451 solves these hassles thanks to its internal, adjustable crossover. The MC451’s crossover tailors the output frequency range of each amplifier section to the attached loudspeaker. Simply set the CROSSOVER POINT knob on the back of the MC451 to the loudspeaker’s crossover point, then frequencies below the crossover point will be sent to the solid state amplifier and frequencies above it will be sent to the vacuum tube amplifier. This adjustable crossover allows you to optimize the performance of both amplifier sections to your speaker's specifications and to your listening preferences. Gain levels for the vacuum tube amplifier can be adjusted from -6dB to +3dB. A direct feed can also be connected to each amplifier section, thus bypassing the internal crossover.

DualView™ Power Output Meter

The MC451 features McIntosh’s DualView™ Power Output Meter. The DualView meter 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 150 Watt vacuum tube amp and the other to the 300 Watt solid state amp. Each meter operates independently of the other and displays the real time power reading of each amplifier section.

Power Guard

Monitors and adjusts the input signal in the 300 Watt solid state amplifier section in real time, then makes inconspicuous volume adjustments to prevent harsh sounding distortion and potential speaker damaging clipping.

Power Guard Screen Grid Sensor® (SGS)

The 150 Watt vacuum tube amplifier section features McIntosh’s Power Guard SGS® technology. Power Guard SGS helps prevent premature vacuum tube failure by monitoring the screen grid current in the KT88 output vacuum tubes. 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 vacuum tubes operating at safe levels.

Sentry Monitor

Sentry Monitor observes the output current and shuts the amplifier off if it ever exceeds safe limits.

Power Control

Power Control sends power on/off signals to other connected McIntosh components for easy system power-up and shutdown.

Gold-plated Solid Cinch™

McIntosh’s patented gold-plated Solid Cinch™ speaker binding posts easily and securely attach the speaker cables.

Heatsink

McIntosh Monogrammed Heatsink™ is connected to advanced high-current output transistors to efficiently cool the solid-state amplifier section.

Power Management

McIntosh’s Power Management System will turn the entire unit off after a set amount of time when no input signal has been detected.

Design

The uncompromising fit and finish of the MC451 is highlighted by familiar McIntosh design cues. The front features a signature black glass faceplate with three clear windows that allow viewing of the vacuum tubes, the DualView meter, two rotary control knobs, an illuminated logo and lettering, and built-in aluminum handles. The top is highlighted by a series of block diagrams printed on glass inserts outlining the circuitry and specifications of the unit. All of this sits atop of stainless steel chassis that's been polished to a pristine mirror finish.