true power

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02-24-2011, 12:01 PM

#31

zzzzzzz

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but like meaningfull in what sense? cuz as soon as you put that same amp in the car those power numbers become meaningless, no?

i was looking at" is the amp what the amp maker states "

02-24-2011, 12:20 PM

#32

Father Yuli

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Quote:

Originally Posted by zzzzzzz

but like meaningfull in what sense? cuz as soon as you put that same amp in the car those power numbers become meaningless, no?

i was looking at" is the amp what the amp maker states "

that is a good point.

with unlimited power supply and a dummy load you can see how honest these companies are.

02-25-2011, 12:34 PM

#33

zzzzzzz

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if the amp maker tells you it is a 5000w amp ! it gets tested by an 3rd party, he tests it and it makes 1200 at 1hms . those power numbers become meaningless form the maker

02-26-2011, 12:20 PM

#34

Haunz

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Quote:

Originally Posted by Father Yuli

but like meaningfull in what sense? cuz as soon as you put that same amp in the car those power numbers become meaningless, no?

measuring an amp's power out put in a car isnt as hard as some of you make it seem. people take these measurments everyday and with simple math you can figure out power, imp, imp rise and many many other things that are not immediately displayed on whatever tool you are using. even the power factor........is very easy to find, there are a number of ways to solve for it. it is just math formulas!!!!!!!!!!

i like how you try to be smart (not that you aren't) and use fancy terms like "power factor" for simple concepts like efficiency.

Meaningful in the sense that the test results are accurate and reproducible... and I don't think you know what I mean by power factor, it has nothing to do with efficiency....

When you measure power with a clamp and a DMM and the load has a capacitive or inductive element to it, you are measuring apparent power (volt-amps or VA)... But what we really want to know is the actual power (watts)...

I won't get too far into it, but in a nuttshell a fraction of the current you measure with your clamp does not actually go through the voice coil on your driver, and is actually fed back into the amplifier...

To find the true power the amplifier is delivering to your load you would need to know the phase angle by which the current lags the voltage.. power factor is equal to the cosine of this phase angle, and is also the ratio of actual power to apparent power...

The bottom line is that using a non-inductive dummy load is the easiest way to find the true power your amplifier can deliver.. and although we don't listen to dummy loads in our cars you can be confident that if one amp delivers 2x the power over another amp into a dummy load, it will also deliver 2x the power to a speaker installed in your car...

Last edited by Haunz; 02-26-2011 at 12:23 PM.

02-26-2011, 12:37 PM

#35

kevmurray

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Quote:

Originally Posted by Haunz

Meaningful in the sense that the test results are accurate and reproducible...

<snip>

The bottom line is that using a non-inductive dummy load is the easiest way to find the true power your amplifier can deliver.. and although we don't listen to dummy loads in our cars you can be confident that if one amp delivers 2x the power over another amp into a dummy load, it will also deliver 2x the power to a speaker installed in your car...

All correct and I agree. For purposes of measuring power output a resistive dummy load should be used. The clamp meter method is good enough though for purposes of comparison. Reactive loads are only needed for more advanced testing.