(b) I am going to argue for totally prohibiting ANY ratings (excluding small print) which are not continuous, 20-20k (or maybe 40-20k?) and <=1% distortion. Yeah, some legitimate companies put a peak power rating which might be believable, but so what, that can be put in smaller print that cognoscenti can read. I'm more concerned about snuffing out "3000 watt" $100 cr@p, so irritating. And takes in the ignorant through no fault of their own.
Great point, I would add that the word "continuous" should be defined better than just to mean using a "continuous sine wave" such as when reference in FTC (
Rule 432) and many manufacturers, without specifying a minimum duration. Same for online/print magazines, what they refer to as "continuous..." tests, its usually a sweep test using a single 1 kHz (e.g. Soundandvision.com), or a 20-20,000 Hz "continuous" sine wave sweep (e.g. Audioholics.com) but in either case the duration for such sweeps would be of short duration, far from being literally continuous.
(e) I'm also not convinced that this conventional wisdom that all channels are never driven at once is true. I've sure attended some movies where it seemed like they were! Hard data is lacking in this area, unless I've just missed it. Certainly I find it weird that AVRs are somehow excused for drooping their power in a manner which would surely be held up as shoddy in outboard amps.
I think you may be right but if and when you do have 7 channel (home use) peaking/maxing out in terms of current demand at the exact same time it would not likely last any longer than a seconds or so, and for such short moment a decent mid range AVRs should be able to handle it without clipping especially when most multi-channel set up would have an active subwoofer or two to take care of the demand from the lowest range such as below 80 Hz. It would be very useful if someone like Gene/Audioholics.com would conduct some tests and publish his findings, using some of the know most demanding BR movies.
Yes I agree it would be nice if AVRs are rated the same, 1,2 or 7 channels driven but if it results in the consumer having to pay much more for mostly power/current reserve that will rarely be used in real world applications then it may not be a good idea. D+M, for example, opted to provide about 70% of the two channel driven rating under 5 channel driven condition, and iirc have been tested to hold roughly true as well with 7 channel driven.
And I'd rather have an AVR that could really do say 7x90 instead of 2x140 drooping to 7x60 or whatever. Even if not clipped, I suspect the better regulated amp could sound better when approaching clipping, and maybe at lower levels besides.
This sounds like a personal choice with no right or wrong.. For me, I'll bet the opposite, and would therefore pick the 2X140 W, 7X60 W and definitely avoid the 7X90 W one but for sure ymmv is golden on this.
the more "regulated" power supply approach adopted by HK in the past did not do well on test benches, their two channel output typically measured so much lower than Denon, Marantz, Pioneer etc., that they also output less under the 5 or 7 channel conditions. This seemed to indicate in such balancing act, the overall outcome is worse. It is understandable, because for class AB amps, the high cost items are the enclosure, power supply, and the heat sinks, so if you spend more of your budget on those items, you have to cut back elsewhere, such as the output devices..