Is there any way to know how many watts you are actually using on your receiver? - AVS Forum
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post #1 of 11 Old 11-18-2008, 05:48 AM - Thread Starter
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Is there any way to know how many watts you are actually using on your receiver, at your own usual listening levels? I mean the power output to the speakers.


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post #2 of 11 Old 11-18-2008, 06:25 AM
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You need the following.....

1. Speaker sensitivity at 1m/1w
2. Distance from speakers.
3. SPL measuring tool

Then you can get something in the ballpark.

It is not "open-minded" to reject knowledge - Bob Lee
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post #3 of 11 Old 11-18-2008, 06:41 AM
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Put a voltmeter across the speaker terminals. Get an average reading on the AC Voltage scale. Then calculate power as:

Power = ( Voltage * Voltage ) / SpeakerResistance

Voltage would be in Volts. SpeakerResistance would be in Ohm (ie. 8 Ohms).

For example, if you read 4 volts, then 4*4/8 is 2 watts.

Mike
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post #4 of 11 Old 11-18-2008, 06:44 AM
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On the (rockford fosgate) web site you can use there formula and punch in the millia amps from your speaker terminals and it converts it to watts being used.
I use this formula for setting my truck amps. It should work just as well with home recievers.
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post #5 of 11 Old 11-18-2008, 07:31 AM
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Get a Kill A Watt: http://www.p3international.com/produ.../P4400-CE.html

Plug receiver in, turn on, and mute. This is your base wattage the receiver draws to run the tuner, scaler, display, fans, and anything else.

Turn speakers on to volume you're interested in.

New wattage - base wattage = speaker power usage.

By the way, Killawatts are pretty useful in general.
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post #6 of 11 Old 11-18-2008, 08:16 AM
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Quote:


New wattage - base wattage = speaker power usage.

By the way, Killawatts are pretty useful in general.


I like the killawatts devices! Definitely gives you and idea what equipment costs you the most!

It is not "open-minded" to reject knowledge - Bob Lee
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post #7 of 11 Old 11-18-2008, 08:46 AM
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They make an inline wattmeter for use with amps and receivers. You can google it.

Remember that a kill a watt meter won't take into account amp efficiency. It's going to be close to 50% for class AB receivers. Efficiency goes up as power goes up, actually.

"But this one goes up to 11"
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post #8 of 11 Old 11-20-2008, 06:42 AM
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Quote:
Originally Posted by Michael Sargent View Post

For example, if you read 4 volts, then 4*4/8 is 2 watts.

P.S. Don't be surprised if you find that at a comfortable listening level you are putting out a lot less that 1 watt per speaker. Most speakers will kick out something around 90 dB for 1 watt (at 1 meter) and 90 dB is pretty loud.
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post #9 of 11 Old 11-20-2008, 08:32 AM
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Quote:
Originally Posted by Michael Sargent View Post

P.S. Don't be surprised if you find that at a comfortable listening level you are putting out a lot less that 1 watt per speaker. Most speakers will kick out something around 90 dB for 1 watt (at 1 meter) and 90 dB is pretty loud.

And what's funny is that many people think they need a 200w/channel amp when they never use more than a couple.

Kevin
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post #10 of 11 Old 11-20-2008, 08:36 AM - Thread Starter
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Actually found this via search engine. Might do it on a breadboard if I feel like it, otherwise I'll just do the V^2/R thing.

Quote:
Originally Posted by Kendrid View Post

And what's funny is that many people think they need a 200w/channel amp when they never use more than a couple.

I know I don't because I've never needed anything more than the receiver itself.


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post #11 of 11 Old 11-20-2008, 10:56 AM
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Quote:
Originally Posted by Michael Sargent View Post

P.S. Don't be surprised if you find that at a comfortable listening level you are putting out a lot less that 1 watt per speaker. Most speakers will kick out something around 90 dB for 1 watt (at 1 meter) and 90 dB is pretty loud.

But then, most people sit more than a meter away, and the sound level goes down exponentially with distance.

And if you want bass, it will soak up more watts.

But it's still true that most people aren't using a lot of watts, especially for a nearfield or desktop system.
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