OK What gives? How can an App using a power consumption of 490 Watts put out 140 Watts per channel X7?
I am getting either the Yahmaha RX-A3010 or the Marantz SR7005. Both claim descrete apps per channel, this is a must for me. Also both have the other features I am looking for. However both seem to be playing with numbers a bit.
Looking into the Owners manuals I find the following information.
App Power watage comsumption / Channels = watts per channel.
Yamaha RX-A3010 490 /7 = 70 rated at 140 watts?
Marantz SR7005 700 /7 = 100 Rated at 125 watts?
So, will I get 140 Watts? Using the same speakers which will be louder? Even though the Marantz is rated at 125 it seems it would be louder based on power consumption.
I wish companie would just be honest.
Similar questions have been asked many times. I beleive Gene had cited an existing standard that required (probably on voluntary basis?) the stated power consumptions to be based on something like 2 channel driven at rated + 1/8 or rated power for the remaining channels but please don't quote me on this. Until manufacturers are required to follow some clearly specified standards, I see at least, but not limited to the following issues for consumers.
1. Manufacturers could pick and choose how to specify their power consumption figures. For example, some (such as HK) will specify "maximum power consumption" without defining what that means, so it could well mean at 10% THD.
2. Some will specify two numbers (such as Yamaha), one undefined but you can assume that they follow a standard, while the other "maximum", like HK. Yamaha products often, but not always, specify the THD, such as 10% THD.
3. Some would specify VA instead of watts, the average public do not know the difference. Even for a competent EE, it is hard to compare VA to watt when comparing different amps. A good rule of thumb is probably to discount the VA by approx. 20%, say Watts=0.8XVA but this is just an approximation as the p.f. seen by the P/S at the input varies with many factors.
4. Some of us would resort to rely on lab measurements from reviews such as those by HTM, S&V, HCC etc., but there is also a huge problem due to the advanced of the "protective" circuit built in to most modern AVRs. I can think of the following examples:
a)Some of those system tend to work more aggressively than others. For example, the much heavier Denon AVR-4810 would give very respectful 5 channel driven output but in the HTM 7 channel driven tests the protective circuit would kick in when output exceed a little under 40W (something like that but I am going by memory) while the $1000 cheaper and much lighter 4310 managed over 100W before the protective circuit shut it down.
b)Different lab measurements use different methods and without knowing the details of their test methodologies it is not possible to do a fair comparison. For example, some lab measurements based their "continuous" output tests on a 1 minute of 10 minute tests while some of them don't even specify the duration, so something like "100W all channel driven continuously...." could mean a 10 second tests while others could mean 1 minute.
For real world enjoyment, none of the above may matter but I am commenting on some pitfalls in trying to compare amp specs based soley on their specified "power consumption" and/or trying to comment on their honesty.
