McIntosh MC7270 (1985–1991)
A high-power solid-state stereo amplifier from McIntosh, built for stability across all speaker loads.
Overview
The McIntosh MC7270 is a stereo power amplifier manufactured from 1985 to 1991. It delivers 270 watts per channel into 1, 2, 4, or 8 ohms, with a mono mode output of 540 watts into 2, 4, 8, or 16 ohms. Designed with McIntosh’s proprietary autoformer outputs, it maintains full power regardless of impedance. The unit features front-panel meters with peak hold, a stereo/mono switch, and a power guard circuit to prevent damage from overloads.
Specifications
| Effective power Stereo | 270W + 270W (into 1 ohm, 2 ohm, 4 ohm, 8 ohm) |
| Effective power Mono | 540W (into 2 ohm, 4 ohm, 8 ohm, 16 ohm) |
| Output bandwidth | 20 Hz to 20 kHz |
| Total harmonic distortion | 0.02% (0.25W to rated output) |
| Cross modulation distortion | 0.02% (any combination of frequencies from 20 Hz to 20 kHz) |
| Frequency response | 20 Hz ~ 20 kHz +0, -0.25 dB |
| Signal-to-noise ratio (A-weighted) | 100dB |
| Damping factor | 30 |
| Load impedance | 1 Ω, 2 Ω, 4 Ω, and 8 Ω (switchable) |
| Input Sensitivity / Impedance | 0.75 V, 2.5 V (Switchable) / 20k Ω |
| Input level adjustment | Left and right independent continuous variable |
| Features | Output Power Meter with Peak Hold, Stereo/Mono Switch, Power guard circuit |
| Power requirements | 100 VAC, 50Hz/60Hz |
| Power consumption | 1,400W (at effective output) |
| Dimensions | Width 411 x Height 181 x Depth 368 mm |
| Weight | 37.2kg |
Design
The MC7270 is a stereo power amplifier equipped with an original digital sonic overload collector. It uses autoformer outputs to ensure consistent power delivery across varying speaker impedances, and features barrier strip speaker connections.
Market
Common restoration procedures include replacing all incandescent bulbs, changing main filter capacitors, calibrating meters, and setting bias and DC offset to service manual specifications. Meter issues are a known maintenance concern, with some units requiring repair or refurbishment of the meter circuitry.
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