McIntosh MAC4280

Documentation on the McIntosh MAC4280 is thin. The record has no confirmed production run, original price or power rating. What exists comes from two places: a McIntosh service manual excerpt and a single used-market listing. Even the model's identity is a little slippery. The service manual separates the MAC4280 (serial numbers to 4001) from the MAC4280B (serial 4001 and above), though all surviving references point to the base MAC4280.

The service manual does say one clear thing: the MAC4280 is a tube-based receiver. It states that no output tube failures had been reported, and it describes each output tube as being "constantly dissected by a 4-way current bridge" - a protective monitoring scheme consistent with McIntosh's house approach. The same source claims the receiver is safe to operate for long periods and that its most outstanding feature is low distortion at low power levels. It also mentions "automatic dynamic range limitation" as part of the design. Later pages carry electrostatic-discharge warnings, which suggests solid-state components in the tuner or preamp sections.

Some listings carry an "A/V" designation, but no video switching or processing specifications appear anywhere in the available material. Neither do tuner specs, power figures or physical dimensions. A HiFI-Stereo advertisement (February 1991, p.53) promoted the MAC4280 as a compact, cool-running, long-life package combining a digital FM/AM tuner, tone-shaping controls and Power Guard speaker protection, alongside the patented Sentry Monitoring circuit. The ad gives no quantitative ratings.

The one concrete market data point is a unit sold on eBay in early 2019 for $398. The seller reported the left channel was faulty (likely a capacitor), noted the matched pair of 4002 output tubes was working, and recommended eventual re-capping.

Known facts, summarized: