Originally Posted by arnyk
Please let me tell the whole story:
The RX-V773WA 95 wpc/8ohm is when only two channels are driven with steady pure sine waves into a resistive load.
The answer is: Steady pure sine waves into a resistive load never happens in actual use
in your listening room because you have this weird preference for music, or am I speaking falsely for you?
Music has at worst half to 1/4 the energy content of pure sine waves. Real world speakers have average impedance of typically 150% of their specified impedance, while those dummy loads on the test bench have approximately 1/3 lower average impedance.
Agree, so far, with everything you said.
Put both of these facts together and you've made the typical mid-market AVR into a picture of power supply and heat sink overkill, and I'm not even getting into the rare possibility that one would ever run his receiver continuously just below clipping for any period of time. Most Audiophiles never use but a fraction of the maximum power possible with their AVR. I'm also ignoring the widespread use of smaller speakers for surround speakers because max power never seems to make it there.
You're talking about ACD power (All Channels Driven) which is a controversy, not an accepted scientific fact. While potentially well-intentioned enough, it also has the effect of being a marketing scam favoring the purchase of wildly overbuilt AVRs.
This is the part I have trouble agreeing with for two reasons:
1. The power consumed by the AVR test that I did tells me if I set to volume on my Yamaha AVR to -10db in stereo mode, producing ~101db peaks with music, I am using a roughly 1/4 the watts than what the PS on the AVR is rated at (125W out of 480W on the RX-V671). Yes, that is a fraction (roughly 1/4th) but that is only stereo mode and for music. With movies, the story gets a bit complex. While average consumption is low with movies, the peaks are higher that what they are with music for the same audio level set on the AVR (-10db).
So, if I play a movie, say LoTR Return of the King, the section where Frodo & Co are lingering outsides the gates of Mordor, trying to find the pass around into Mordor - plenty of dialogue and sudden bursts of audio. I set my AVR to -10db and put it in Stereo mode. Peak power consumption goes to ~170W. Add two surround speakers and now the peak power consumption goes to ~200W.
As we do these readings, thing to keep in mind, is that I am reading power consumed at the electrical outlet. This reading is an absolute in the sense, this energy has to spent somewhere down the system between the AVR (heat, amplification, digital circuitry etc) and speakers (coil, mechanical movement).
At 200W power consumption, assuming 80% PS efficiency, we are using over 50% of what the PS can handle. I wouldn't say that is a fraction. At 170W power consumption in stereo mode, taking out the idle power use of about ~45W, we have 145W being consumed by the amplifier. Take out a 40% for worst case amp efficiency, and we are delivering ~50W to each speaker in stereo mode. Again, we are above 50% of the rated wpc for each channel in stereo mode. So we are below the limit and have good headroom but I wouldn't call it a fraction.
Obviously, you could produce test data and convince me otherwise
2. From the commercial point of view, overbuilding these AVRs doesn't make sense. If 80% of consumers are going to heavily under utilize their AVRs then why spend money making them all that beefier, bigger and heavier? You spend more money on parts, storage, shipping etc etc. As a manufacturer, I would build these AVRs where they fly just under the radar for most use cases so consumers don't complain of poor audio and I don't end up spending $$$ more than I need to on component/manufacturing and other costs. With lots of competition in this arena, I'd bet that is what the manufacturers have done.
Just my 2 cents worth
As always, show me data otherwise with means to replicate the results (aka a scientific process to test) and I will shut my trap