audio power amplifier ratings

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guitars13339

Joined Jun 13, 2012
3
How is it possible for any amplifier to put out more wattage to the speakers than what it pulls from the wall outlet?
How can amp companies claim these impossible wattages?
 
the chief basic building block of amplifier is a transistor whatever the type implying that u have what we call DC current gain the one thats behind the wattage amplification tho most power comes from the batter particular amplifier is connected to
 

crutschow

Joined Mar 14, 2008
34,452
It has nothing to do with whatever KASSIMSAMJI said. :confused: It's call specmanship (lies). You can't get more continuous power from all channels than drawn from the mains. But they often rate the power from only one or two channels at a time putting out maximum power. That way the maximum audio output will be no more than the mains power. Another trick is to use peak power which uses the energy stored in the power supply filter capacitors to provide a momentary large power peak in excess of what the amp can continuously deliver. Caveat Emptor. ;)
 

WBahn

Joined Mar 31, 2012
30,062
How is it possible for any amplifier to put out more wattage to the speakers than what it pulls from the wall outlet?
How can amp companies claim these impossible wattages?
Are they still calling it "peak music power" or some such crap?

They do it the same way that air compressor manufacturers are able to put stickers claiming 6HP on the side of a compressor with a 120VAC/15A plug on it.

They lie.

It's pure specsmanship in which marketing people, who seldom know a damn thing about engineering even if they have an engineering degree, come up with the most absurd measurement they can think of that will result in a high number with the right units (and they aren't too picky there, either) and plaster on all the advertisements whether they know that they are misrepresenting the real case wildly or not (and most of the time they damn well do).
 

wmodavis

Joined Oct 23, 2010
739
First off it is NOT possible to "put out more wattage to the speakers than what it pulls from the wall outlet". That would require a breaking of the law of conservation of energy and result in an efficiency of greater then 100%. Just not possible.

UNLESS... the method of measuring the supply power and the output power are different, as several have intimated. I.E. rms power vs peak power. Not the same animal. And back in my day there were even some who rated amplifier output in the super bogus "peak-to-peak music power". That doubles the value of 'peak music power'.

But as stated the advertised specs are usually written by the marketing person - not the engineering group. You do not need to be a liar to be in marketing but it sure helps. It make the sales go up and the company bottom line to look better and the marketing guy's career to advance. And that whole string of events is also made possible by the mostly unknowing public who purchases the produce. And more power is better - right?

Power output specs should ALWAYS be suspect unless there is clear indication of how that power was measured/calculated or what standard was follower. And even then you should measure it yourself to be sure.
 

Audioguru

Joined Dec 20, 2007
11,248
I recently bought some low cost powered speakers that sound fantastic. They are rated at 150W or 75W. Those ratings are for WHATS!

The small power transformer is labelled "9VAC/1.1A" (9.9W). The amplifiers are probably 60% efficient so only a total of 6W goes to the two satellite stereo speakers and the sub-woofer.
 

Audioguru

Joined Dec 20, 2007
11,248
The rating of 150W is the actual output of 6W times the age (25) of the marketing idiot.
Peak power (sometimes called Maximum power) is phoney baloney.
 
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