McIntosh MC501 (2003–2012)
The MC501 is a solid-state monoblock power amplifier, handcrafted in Binghamton, New York, and produced from 2003 to 2012. It's rated at 500 watts minimum continuous average power from 20Hz to 20kHz into 2, 4, or 8 ohm loads. That's the same full output whatever the speaker impedance, which is the whole point of McIntosh's output Autoformer. The design is fully quad-balanced, with symmetrical balanced circuitry from input to output. Two matched push-pull amplifiers have their outputs combined in the Autoformer, and McIntosh credits the double-balanced configuration for the amp's very low distortion. Protection is thorough: Power Guard, Sentry Monitor, plus DC, thermal, and turn-on delay safeguards. A backlit "Blue Eyes" output meter shows real-time power and can be switched off. Inputs are balanced XLR and unbalanced RCA - 4.2V into 20k ohms balanced, 2.1V into 10k ohms unbalanced. There's also a 12-volt trigger for remote power-on from a compatible McIntosh control center, and the trigger won't work unless that connection is made.
The MC501 weighs 91.5 pounds (41.5 kilograms). The owner's manual is blunt that two or more people are needed to move it safely. The manual also lists power requirements by region, from 100V at 8 amps up to 240V at 3.3 amps. The service documentation gives these distortion figures: maximum total harmonic distortion of 0.005% at any power level from 250 milliwatts to rated output, and maximum intermodulation distortion of 0.005% if instantaneous peak output stays within twice rated power, 20Hz-20kHz. Signal-to-noise is 97dB A-weighted (124dB below rated output). Dimensions are 17-1/2" W × 9-7/16" H × 14-3/4" D including clearance for connectors.
Reception during its run was strong. It was recognized as a Stereophile Product of the Year, and Hi-Fi News covered it alongside other period publications. The original price was $11,000 per unit, with a Japanese retail listing around 2007 showing ¥682,500 including tax. One dealer account describes taking a pair in trade from a customer who'd driven Sonus Faber speakers with them, and adjusting the bias to factory spec before resale. A few specs commonly asked about aren't in the surviving record: no damping factor, no confirmed production quantities, and no documented common failure points beyond the general note that bias should be checked against factory spec on a used pair.
- Type: solid-state monoblock power amplifier
- Years: 2003–2012
- Power: 500W minimum continuous average, 20Hz–20kHz into 2/4/8 ohms
- THD: 0.005% max, 250mW to rated output
- IMD: 0.005% max (peak ≤ 2× rated, 20Hz–20kHz)
- S/N: 97dB A-weighted (124dB below rated output)
- Inputs: balanced XLR (4.2V / 20kΩ), unbalanced RCA (2.1V / 10kΩ); 12V trigger
- Dimensions: 17-1/2" W × 9-7/16" H × 14-3/4" D (incl. connector clearance)
- Weight: 91.5 lbs (41.5 kg)
- Original price: $11,000 per unit
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