How can I measure how many watts my amp is putting out?

[Nevalite 10+ year member]

Hey,

I just got my first install up and running and I wanted to test it to make sure the amp is putting out its full potential. I imagine I can do this with a DMM?

Could someone let me know how, thanks.

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[outspoken 10+ year member]

http://www.bcae1.com/

 

[Nevalite 10+ year member]

You couldnt like measure the volts and multiply it by the amps and get the watts?

 

[squeak9798 5,000+ posts]

You couldnt like measure the volts and multiply it by the amps and get the watts?

Generally not a good method as it gives you no indication of the level of distortion the amplifier is producing while taking the measuring. A measurement taken at high levels of distortion, for example, is of very little value.

To really do it "right" you need a regulated power supply, resistor, oscilloscope & DMM.

 

[thch 10+ year member]

DMM -- measure voltage, V^2 / R, assumes fixed R and clean signal

Clamp -- measures current, I^2 * R, assumes fixed R and clean signal

DMM+Clamp -- measures voltage and current. V * I. can be low as the speaker's actual impedance may be higher then the nominal R = V / I. Also assumes a clean signal

OScope -- measures voltage, V^2 / R, assumes fixed R, signal should be clean

Oscope + Clamp -- Measures voltage and current. can be low. Signal should be clean

Oscope + Current Transducer -- Measures waveforms of both voltage and current, can calculate actual power (defined by used energy), can give low results as per above, but gives the most accurate "actual" results.

There are many things you can determine -- maximum output power, actual output power (with speaker), speaker impedance.

Simple testing may not give the same number as on the box -- the test conditions may be different. in the end, there is too much emphasis placed on such measurements.

(side note, anyone ever try one of theose "kill-a-watt" meters, they should be able to give power, apparent power, and power factor, as well as volts and ampres for 60hz)

 

[casper97ta 10+ year member]

Listen to squeak. Unless you can duplicate a controlled environment you cant get exact specs. You can get a ballpark number by doing the methods mentioned.

 

[ngsm13 5,000+ posts]

Generally not a good method as it gives you no indication of the level of distortion the amplifier is producing while taking the measuring. A measurement taken at high levels of distortion, for example, is of very little value.
To really do it "right" you need a regulated power supply, resistor, oscilloscope & DMM.

DMM -- measure voltage, V^2 / R, assumes fixed R and clean signalClamp -- measures current, I^2 * R, assumes fixed R and clean signal

DMM+Clamp -- measures voltage and current. V * I. can be low as the speaker's actual impedance may be higher then the nominal R = V / I. Also assumes a clean signal

OScope -- measures voltage, V^2 / R, assumes fixed R, signal should be clean

Oscope + Clamp -- Measures voltage and current. can be low. Signal should be clean

Oscope + Current Transducer -- Measures waveforms of both voltage and current, can calculate actual power (defined by used energy), can give low results as per above, but gives the most accurate "actual" results.

There are many things you can determine -- maximum output power, actual output power (with speaker), speaker impedance.

Simple testing may not give the same number as on the box -- the test conditions may be different. in the end, there is too much emphasis placed on such measurements.

(side note, anyone ever try one of theose "kill-a-watt" meters, they should be able to give power, apparent power, and power factor, as well as volts and ampres for 60hz)

I should delete all post except these two...

Most others don't matter, or are incorrect.

nG

 

[pensacol 10+ year member]

I should delete all post except these two...
Most others don't matter, or are incorrect.

nG

Quick question (don't mean to hijack your thread), but why say "I should delete all post except" the one's that actually pertain to the guys question. Why don't you just do it. If you would start, people might be able to get some help here instead of the usual, "You're a ***, or buy a FI, or why don't you just kill yourself, for not knowing what you are doing and buying those" Wouldn't that make more sense? I don't mean to be an ***, but was just curious.

 

[ngsm13 5,000+ posts]

Well, cleaned up some.

nG

 

[pensacol 10+ year member]

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OK man. Thanks, you can delete these posts if you want to.