Power ratings

[krusty_916]

This may be a simple question, but I am a newbie to this. I have noticed a wide range in power ratings between receivers. Some Sony receivers are rated at 1000W while a Harmon-Kardon may be rated and half that. This doesn't mean it's twice as powerful, right? I'm guessing that not all watts are created equal. If this is true, how do you know what power rating to look for. I have some speakers that can take 140Watts, does that mean a reciever pumping out 100W per channel is going to be better then one pumping out 55W?

Vernon

[57]

Watts are equal, what's not equal is the specification:

- Total Watts - no distortion number given
- Total Watts - a high distortion number
- Total Watts - a low distortion number
- Watts per channel, no distortion or frequency response given, no indication of number of channels driven
- Watts per channel, two channels driven, at 1 kHz
- Watts per channel, all channels driven, 20-20kHz, 0.05% distortion.

The above is an indication of the loosest spec to the tightest. The Wattage difference could be as much as a factor of 10 or 100 between the top and the bottom. It only makes sense since a $200 HTiB rated at 1000W is simply not even going to be close to an AVR rated similarly, but all channels driven, 20-20kHz, low distortion that costs $2000.

By way of example, a $200 HTiB rated at 1000W, may not even be able to produce 1W/ch, 20-20kHz, 0.05% distortion. Basically, you get roughly what you pay for and Watts should be one of your last concerns when picking out an AVR - see:

http://www.digitalhome.ca/forum/showthread.php?t=76082 AVR Features

See the following previous thread on the topic:

http://www.digitalhome.ca/forum/showthread.php?t=27306

[jlet]

Speakers should also have 2 power ratings:
1) x Watts at y% distortion which will be a lot smaller than 2 below
2) z Watts before damage (smoke power rating)
The power rating you usually see on speakers is #2 - the "smoke" (damage) rating.

[NESTER]

What feels like twice as loud is ten times the power! A 3db increase can be confidently noticed by a novice and that takes twice the power. 1 watt becomes 2 and 600 becomes 1200. And sound should be dynamic. peaks and soft parts. Do you have reserve power for the peaks. If your source is poorly made CD's and MP3's there is no dynamics to concern your self with. Music that sounds like a steady tone has no need for life like capable reserves of power.

[springle]

I noticed these statistics in the July 2008 HOME THEATRE magazine.

For a Denon AVR-3808, published at 130 watts/channel, tested into 5 channels at 0.1% distortion - 118.9 watts/channel, and at 1% distortion, 138 watts/channel. This AVR weighs 39 pounds.

For a Yamaha RX-V863, published at 105 watts/channel, tested into 5 channels at 0.1% distortion, 42.6 watts/channel, and at 1% distortion, 48.4 watts/channel. This AVR weighs 26 pounds.

Everything into 8 Ohms.

Obviously the Denon costs more, but Yamaha is not a fly-by-night manufacturer. It's puzzling why they fudge their published numbers.

Remember, weight is the quick, no instruments required, test.

[Shear Force]

What are numbers for all channels driven; .1% distortion, 20 to 20k?
You can be sure that they are less than 119 & 42 watts quoted in the article.

Only companies like NAD, H/K, B&K, Outlaw, Sunfire, Emotiva and high end companies admit to the 1972 FCC standards.

[springle]

Yamaha RX-V863 - 41.6 watts/channel @ 0.1% distortion

Denon AVR-3808CI - 113.5 watts/channel @ 0.1% distortion

Not significantly differently from 5 channels driven.

[Mr. Perfect]

A power rating at 1 frequency is not the same as a power rating across the whole audio spectrum. It could be up to 20% lower when measured 20 to 20k.

[GreatWhtNorth]

Remember, weight is the quick, no instruments required, test.

That is like saying a 100lb amp is going to be more powerful than a 60lb amp. I can show you many amps that will prove this completely false.

Weight is not a guide to measure power, it is only a mere indication and at times not the truth. It however is true enough of the time that it's become a generalization....but generalizations are not fact.

[Tom.F.1]

The best Indicator are the Real Specifications, and even then, they have to be taken with a grain of salt. These look good on the surface, but notice what's missing? Nowhere ever does it say 'all channels driven', it only lists 2 channels at a time.
This is sold as 130 watts per channel, 910 total. I call it 110. But then i have 6 ohm speakers.....

Amplifier section
Continuous average power output of 110 watts* per
channel, min., at 8 ohms, from 20 Hz to 20 000 Hz
with no more than 0.09 %** total harmonic
distortion (front).
Continuous Power Output (20 Hz to 20 kHz, 8 Ω, 0.09 %)
Front. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 W + 110 W
Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 W
Surround . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 W + 110 W
Surround back . . . . . . . . . . . . . . . . . . . . . . . . 110 W + 110 W
Continuous Power Output (1 kHz, 6 Ω, 1.0 %)
Front. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 W + 150 W
Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 W
Surround . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 W + 150 W
Surround back . . . . . . . . . . . . . . . . . . . . . . . . 150 W + 150 W
Related Power Output (1 kHz, 8 Ω, 0.05 %)
Front. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 W per channel
Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 W
Surround . . . . . . . . . . . . . . . . . . . . . . . . . . 130 W per channel
Total harmonic distortion. . . . . . . . . . . . . . . . . . . . . . . . 0.09 %
(20 Hz to 20 kHz, 110 W, 8 Ω)
* Measured pursuant to the Federal Trade Commission’s
Trade Regulation rule on Power Output Claims for Amplifiers
** Measured by Audio Spectrum Analyzer

So, I played a full CD (hard Rock music) stereo only, (only the 2 speakers) at 0 volume and the thing got almost hot enough to fry an egg. I was worried about the heat, but it didn't hurt it and it didn't shut down.

[SliderIQ]

About 20 years ago, there was an audio show in Hamilton. NAD hooked up two stereo amplifiers, one was another major brand (which I forgot now) and second was NAD. They played piano music on both and connected a scope across the load.

The "other" brand was rated much higher than NAD what it had lower dynamic headroom. Most of the music was around 20 watts but some peaks were clipping at 140 watts. On the NAD, you could see these peaks hitting 170-180 watts. NAD had dynamic power rating of 200 watts.

I own a NAD 7400 receiver. It has 2.7db headroom and it can pump 440 watt peaks into 2 ohms. No wonder, I can get half the money I paid for it 19 years ago (not that I would sell it), but I can't even get one sixth for my seven year old Denon 3801.

[caper_26]

Boy this can really get confusing fast. One needs to learn about frequency spectrum and THD before they can begin to understand the equally confusing part about the Wattage specs. And to add to it all, wouldn't it also depend on whether your speakers are set to SMALL or LARGE, since some freq's will be routed to sub-pre out, which will free up some power from the to be used driving the speakers?? If they are set small, more power from AVR amp available?? It would sure be nice to have ACTUAL measurements for a receiver. Can anyone comment on the V565 actual specs? The manual says:
Min RMS power for Front, Center, Surround, Surround back:
- 1 kHz, 0.9% THD, 8 Ohm ........... 90 W

To me, that's all speakers driven, but then we have the 1 kHz spec...