checking actually output

[optimusprime 10+ year member]

if you were to measure how many amps your amplifier was drawing and then multiply it by the voltage on the speaker terminals would that give you the actual output power in watts? :edit: this is what i get for typing while distracted.

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[Dirtrider4eva 10+ year member]

i believe in order to correctly calculate the output of your amp. you need a DDM for impedence, and a Digital clamp to measure AC voltage that records a peak.

you take that peak, multiply it by your voltage, and thats the output at the Impendence of your amp.

remember when you play different Hz tones, your impedence will stay the same, but on music its varying.

 

[optimusprime 10+ year member]

if you can check the ac voltage of an electrical outlet why cant you check the ac voltage of an amplifier with a DMM?

 

[Kangaroux 5,000+ posts]

i believe in order to correctly calculate the output of your amp. you need a DDM for impedence, and a Digital clamp to measure AC voltage that records a peak.you take that peak, multiply it by your voltage, and thats the output at the Impendence of your amp.

remember when you play different Hz tones, your impedence will stay the same, but on music its varying.

wat

Different frequencies are different impedances regardless if it's music or tones.

 

[subzero 5,000+ posts]

set dmm to AC, measure max ac v out at speakers out, and then measure ohms and then measure DC at amp power in.

 

[Dirtrider4eva 10+ year member]

wat
Different frequencies are different impedances regardless if it's music or tones.

correct. but if you play say, a 50 hz continually, the impedence from that tone will remain constant so you will be able to calculate the continual impedence. music changes to fast to ever get a reading of peak output and impedence at the same time.

 

[optimusprime 10+ year member]

so a clamp isnt needed really it just makes things alot easier.

 

[keep_hope_alive Premium Member]

Measuring input current and voltage gives power drawn by the amp, but not power output. Amp converts some power to heat, so you need to know efficiency at that load impedance and output level.

Play a test tone, measure AC voltage at speaker terminals, refer to impedance curve of speaker or use a dummy load, then use ohm's law to calc output power. A scope is required to verify you aren't distorting. Some DMM's measure RMS some do not. You need to know whatnyour meter measures. true RMS meters are more expensive

 

[keep_hope_alive Premium Member]

P=v^2/r

 

[bubbagumper6 5,000+ posts]

Measuring input current and voltage gives power drawn by the amp, but not power output. Amp converts some power to heat, so you need to know efficiency at that load impedance and output level.
Play a test tone, measure AC voltage at speaker terminals, refer to impedance curve of speaker or use a dummy load, then use ohm's law to calc output power. A scope is required to verify you aren't distorting. Some DMM's measure RMS some do not. You need to know whatnyour meter measures. true RMS meters are more expensive

This is the important part. Without monitoring THD your measurements are only a guess-timate.

 

[akheathen Premium Member]

well, you could refer to the impedance curve, but that also is just guessing, because that is tested either free-air, or in something other than you have it set up. impedance rise happens, and you can find what it is by clamping it and measuring amps, while simultaneously measuring ac voltage, both from the same speaker outputs. you can get decently close with just a clamp and dmm on the voltage, as long as you can pick up on the distortion, but to get exact, yes you need a scope. as mentioned, you can build yourself, or buy, a dummy load, and measure the voltage.

 

[keep_hope_alive Premium Member]

really, you're probably close enough just using a nominal impedance value and not worrying so much about the exact impedance at that moment. we all know that impedance varies with not only frequency and the enclosure, but also temperature! it's almost pointless to attempt to track it.

a clamp meter on the output would work with a constant tone and a 50-60Hz tone. at other frequencies, it depends on the clamp meters' ability to track it - not all meters are created equal. you'd have to refer to the tolerances and specifications.