McIntosh MC451 With Hybrid Drive Technology – First Look

All Image Credit: McIntosh

The MC451 is the latest addition to the McIntosh Hybrid drive range. It is a dual mono power amplifier that employees both tube and solid state technology extracting the best from each device type and providing 300 watts of solid state and 150 watts of tube power in one chassis.

Hybrid Drive™ is a McIntosh technology that gives the audiophile a simplified way of enjoying the rich sound of vacuum tubes for the mid-range and upper frequencies and the power of solid state circuits to support tight, deep and powerful bass, all in a single, smaller and easy to use product.

This integration of the two amplifier technologies simplifies bi-amping and wiring giving users the best of both worlds. The vacuum tube section drives the speaker’s midranges and tweeters, while the solid state section drives the bass units(s). The 150 Watt vacuum tube amplifier is powered by four KT88 output tubes, plus two 12AT7 and one 12AX7A signal tube. They use the McIntosh 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 our Autoformer™ technology.

The large but quiet toroidal transformer supplies enough power so that neither amplifier affects the performance of the other.

The adjustable crossover – 100Hz to 1000Hz, allows the user 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 electronic crossover and supporting the use of your speakers passive crossovers.

Finally, the MC451 features a variety of McIntosh patented technologies, including Power Guard and Power Guard SGS, together monogrammed heatsinks and the signature DualView Power Output Meter.

Features At A Glance:

• 300W Solid State Amplifier:
  • Output Autoformer with 2, 4, 8Ω taps
  • Power Guard and Sentry Monitor
  • Solid-state input doubles as the mono input when using the internal crossover
  • Separate inputs for the Vacuum Tube and Solid-state amplifiers are provided for using an external crossover
• 150W Vacuum Tube Amplifier:
  • Unity Coupled Circuit Output Transformer with 2, 4, 8Ω taps
  • Power Guard SGS and Sentry Monitor
  • Direct Input for Using an External Crossover
  • Illuminated Driver Tubes
• Crossover:
  • 1 Knob for Solid State / Tube Balance: -6dB to +3dB
  • 1 Knob for Crossover Frequency: 100Hz-1000Hz

Technical Specifications:

• Power Output per Channel
  • Solid State section: 300 Watts @ 2, 4 or 8 Ohms
  • Vacuum Tube section: 150 Watts @ 2, 4 or 8 Ohms
• S/N below rated output
  • Solid State section: 118dB
  • Vacuum Tube section: 112dB
• Rated Power Band
  • Solid State section: 20Hz to 20kHz
  • Vacuum Tube section: 20Hz to 20kHz
• Dynamic Headroom
  • Solid State section: 2.5dB
  • Vacuum Tube section: 1.2dB
• Frequency Response
  • Solid State section:
    • +0, -0.25dB from 20Hz to 20,000Hz
    • +0, -3dB from 10Hz to 100,000Hz
  • Vacuum Tube section:
    • +0, -0.5dB from 20Hz to 20,000Hz
    • +0, -3dB from 10Hz to 70,000Hz
• Total Harmonic Distortion
  • Solid State section: 0.005% maximum harmonic distortion at any power level from 250 milliwatts to rated power, 20Hz to 20,000Hz
  • Vacuum Tube section: 0.5% maximum harmonic distortion at any power level from 250 milliwatts to rated power, 20Hz to 20,000Hz
• Damping Factor:
  • Solid State section: >40
  • Vacuum Tube section: >18