McIntosh Amp Ratings

Aball-

You're spot on about the McIntosh Autoformer...it can deliver more power at lower impedances but it, like all other amplifiers, is limited. The Mac is probably more conservative as part of their design intent is to minimize heat generated to prolong life.

also, Autoformers kill damping factor, which probably explains why traditional output designs that offer better control of the woofers are prefered by some.

I have owned quite a few Mac amps.  My favoirte was the MC-2300, which did not have an autoformer.  With regard to Macs power rating CONSERATIVE is their practice.  The MC-2300 could put out nearly 500 watts into an 8 ohm load though rated at 300 per side.  Strapped in mono, power deliery was astronamical, as it would easliy better 1500 watts.  I know beacuse I still have the bench sheet from my personal amp tested during a Mac clinic.

Further, this amps was factory rated to drive a half ohm load.  Not many compaines have that type of confidence in their products ability to drive loads.  Damping factor was always stated with low numbers.  This is because a damping factor of more than 20, was thought to be inaudible and ridiculous according the Mac engineers of the day, so that was all they ever tested for.  Any Mac amp when tested will easily give you a high damping factor.

Mac specs are always quoted as "worst case".  Who else does that? No one I can think of..

Norman

i've read before that most mac amps would put out about 1/3 more watts then the rated output. 300 watt per chanell amp would put out 400 watts per chanell. any comments on this?

It depends on how the wattage is measured or more specifically the distortion level % at +/- dB. I have a pair of MC2200s and according to the performance graph shown in the owners manual, the distortion level at 200 wpc is basically a non issue. At 270 wpc the distortion is just about the level where most other manufacturers advertise their continuous power ratings. On the amp itself, it says 200 wpc minimum power rating. So I guess in this case the 1/3 higher power rating is about right.