Integrated Amplifiers

The combination of McIntosh's 'Power Guard' and 'Sentry Monitor' protection regimes are remarkably effective at preventing the MA252's output stage from 'clipping' much beyond 1% distortion no matter how hard the MA252 is pushed. However, the maximum dynamic power output figures recorded here of 152W, 285W, 155W and 52W (into 8, 4, 2 and 1ohm loads) are still entirely representative of what might be achieved in a real system [see Graph 1, below]. Also, with full power outputs of 2x125W/8ohm and 2x200W/4ohm comfortably exceeding McIntosh's 100W/160W rating, it's clear that while the MA252 is powerful it's not especially tolerant of difficult loads and is ideally partnered with loudspeakers offering a 6/8ohm nominal load. The triode/power amp PSU also generates a little extra noise so the A-wtd S/N ratio is also slightly below average at 80dB (re. 0dBW), but this will only likely become apparent with super-sensitive speakers.

Otherwise the MA252 is a model citizen, offering a very wide bandwidth (frequency response) with mere ±0.5dB limits over a 8Hz-100kHz span. The low 0.04ohm source impedance holds through bass and midrange as does distortion which stays below 0.002% from 20Hz-10kHz at 10W/8ohm, increasing to 0.008%/20kHz. The lowest distortion is through midrange frequencies at 5-20W output where it drops to ~0.0006%, increasing to the previously mentioned 0.002% at lower (1W) and higher (60-100W) power outputs. Either way, THD is very well managed within the MA252. The digitally-governed volume control offers excellent channel balance (0.04dB at 0dBW) and channel separation is also very good at >80dB across the audioband. PM