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  Watts RMS...What does it mean 
 
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Tracy Brown May 14, 2010, 09:55pm EDT Reply - Quote - Report Abuse
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I can remember many moons ago when a 80 watt per channel RMS amp would blow the neighbours windows out.
These days I see advertised 1000watt RMS amps being nearly the norm for home theaters.

These plastic things weigh just about nothing at all and the speakers similar.

How far downhill have we gone when companies are allowed to get away with these specs?

Or do my ears deceive me ? RMS? What does it mean these days?


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<a class= May 15, 2010, 04:04am EDT Reply - Quote - Report Abuse
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>> Re: Watts RMS...What does it mean
In common use, the terms "RMS power" or "watts RMS" are erroneously used to describe average power. A 100 "watt RMS" amplifier can produce a sine-wave of 100 watt average into its load. With music, the total actual power would be less. With a square-wave, it would be more.

http://en.wikipedia.org/wiki/Audio_power

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Tracy Brown May 15, 2010, 09:38pm EDT Reply - Quote - Report Abuse
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Edited: May 15, 2010, 09:39pm EDT

 
>> Re: Watts RMS...What does it mean
I repeat my question.How do these folk get away with it ?

Are these 1000watt RMS Home theatre units really 1000watts RMS ?

I can remember Ohms law which tells us Watts= E squared over Ohms.

If I was testing an amplifier rated at say 50 watts RMS I'd do this

Input a 1000 hz sine wave to the amp.

I would hook up an osciloscope across an 8 ohm resistor or across a 8 ohm speaker, I should be able to see a nice sine wave of 20volts RMS before any amplifier clipping

Pretty simple stuff and of course voltages will vary according to speaker impedance.
The lower the speaker impedance the highr the output, if the Amp is designed for that impedance speakers

What method is used nowadays ?

Are these plastic looking amps and apeakers capable of outputting 1000 watts RMS??

Certainly would be a cheap way of setting up a outside concert in a large field !!

Can anyone help me with this, 'cause if they are a genuine 1000 watts, it's a quantum leap!!

<a class= May 16, 2010, 02:53am EDT Reply - Quote - Report Abuse
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>> Re: Watts RMS...What does it mean
It's the same story as bhp in cars today. They are basicallys**tting you. I've seen tests to when they take a brand new car to a dyno run and instead of advertised 400 bhp it has like 330.

I bet there is the same story with home theater systems. Though the more expensive it is, the more likely it is to be true.

If you pick up a Ferrari F430 brand new, it will actually have 483 hp or close to it. But it is hella expensive though. Probably same thing with home theater setups, if you go over 2k, they might actually have that kinda power.

On the side note, about cars, I love how the Nissan solved the problem of lying about cars bhp. With their latest Nissan GT-R they've just said: "We don't now how much bhp it got." LOL at least they didn't lie.

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