Originally Posted by turnne1
You really don't know if that is the case....
Oh, I have a pretty good idea though...
First of all, did read the review of the A3000 at the Audioholics site? The author specifically included the power test results of the Emotiva UPA-7 separates amplifier, because the A3000 tested nearly identically to (in several cases a bit better than) the UPA-7 on every test except the continuous ACD test. The Emotiva, which did not have a protection circuit tested continuous ACD at 108W & 117W (0.1 & 1.0 THD+N). The implication there, is that we have every reason to believe that the Yamaha has the guts to do roughly as well as the Emotiva on continuous ACD, were it not for the protection circuitry.
Without wasting TOO much more time on this topic (i.e. searching for better examples of receivers without protection circuitry that are rated around 7x70wpc), here is one more example, the little brother of your venerable TX-SR875, the TX-SR575. It's rated at 7x75wpc (according to HT mag that is, the Onkyo web site now claims 7x80wpc). HT mag tested it
Originally Posted by Home Theater Magazine
This graph shows that the TX-SR575 ... with two channels driving 8-ohm loads
, reaches 0.1 percent distortion at 120.6 watts and 1 percent distortion at 144.2 watts. Into 4 ohms, the amplifier reaches 0.1 percent distortion at 160.7 watts and 1 percent distortion at 200.9 watts.
The A3000 easily beats each of those numbers by a large margin. On the continuous ACD test, the Onkyo 575 came in at 59.4W (7ch) and 82.6W (5ch) so pretty close to the 65W ACD the A3000 is purposely held back to. So as I said before, find an amp without protection circuitry that benches near the 65wpc continuous ACD of the protected A3000, and I guarantee the A3000 will dance circles around it.
And yes, you are most certainly misrepresenting the abilities of the A3000 when you continue to quote the 65wpc continuous ACD results as even remotely relevant or meaningful.
The continuous ACD test is unrealistic for many reasons, most of which I don't have time to go into. But if you read up on it
, you'll learn that 99% of American households can not supply enough power to a receiver over standard code household electrical systems and wiring. The most a standard house could support, on a dedicated fuse would be *around* 700W (IIRC) delivered by the receiver (i.e. after amplifier efficiency and wiring and other losses are accounted for). Some people think they're going high-end and install 20A fuses and wires for their HT, but that really doesn't get you much more. The power cord that comes with most receivers (even "flagship" models) is itself a huge limiting factor.
In order to actually run these continuous ACD tests, most magazines (e- and print) have to have a dedicated lab with the equivalent of MULTIPLE electric dryer hookups for their amplifier testing.
So you see, having a protection circuit helps protect not only your receiver (and speakers), but also your home wiring, from idiots who run party mode with the volume "all the way to eleven". Even in this scenario you would either fry your equipment (or blow some speakers) or throw a fuse before you ever got close to the rated abilities of your amplifier.
Not to mention that REAL material (neither movies NOR music) never, ever, EVER gets close to the stress that a continuous ACD test imposes on an amp.
You ask why you should be interested in anything other than continuous ACD testing for a multi-channel amp. You should be interested in the other tests because they more accurately represent what you are likely to experience when you use your amp at home. To go back to the car analogy... if I'm buying a sports car, the things I'm most interested in are acceleration, handling and braking. I want to know how quickly it can do the 1/4 mile, go from 0-60mph, and from 55 to 85mph. I don't care what it's top speed is, because I know I'll never go much over 100mph if ever. So the top-speed test provides meaningless bragging rights, and nothing more.
For amplifier power, you should care about dynamic power, and full-bandwidth 2-channel power, primarily. BTW, Dynamic power is what THX use to rate amplifiers for certification, IIRC.
EDIT: here are two other receivers that are a good comparison to the A3000:
The Marantz SR6004
and the Denon AVR-4310CI
If you open those two pages, and the A3000 test page
and compare the power test tables, specifically comparing identical or similar tests, you will quickly see that the Yamaha is much superior to the Marantz, despite the Marantz having a better continuous ACD test (7x71W), and that the A3000 is comparable to the Denon, despite it having a continuous ACD test of 7x95W to the A3000's 7x65W.