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Measure THD on my power amp, what intrument?

post #1 of 5
2/13/11 at 4:28am
Thread Starter 

Hi

 

I have an Audio research D250, its a wonderfull amp even though it eats a fortune of tubes and produce to much heat to be used in the summer.

I have changed all the tubes and have done all the adjustments except "Ac balance" and now I need your help.

 

The manual says I should measure  thd or thd+noise when driving a 16ohm load with 10W @1khz and then adjust it for >0.005% THD or 0.02% THD+Noise.

 

I have 4x 4ohm 5W resistors to get the 16ohm load, and I can generate a 1khz signal with my dac, But what kind of intrument do I need to measurre thd or thd+N?

 

Thanks


Edited by vlb - 2/13/11 at 4:00pm
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post #2 of 5
2/13/11 at 8:42am

Does this help?

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post #3 of 5
2/13/11 at 8:49am

Here is a good website I found.

Looks like they have lots of interesting stuff.

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post #4 of 5
2/13/11 at 8:57pm

The most inexpensive (and quite effective) way to do this is to use a good pro-grade computer sound card and RMAA software.  The key is your choice of sound card -- it needs to have lower noise and distortion than the amp you're trying to measure, or you'd just be measuring the sound card itself.

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post #5 of 5
2/14/11 at 3:21am
Thread Starter 

Thanks!

Ive tried using the soundcard (xf-fi) but it doesent go as low as >0.005% THD at least not with the software I tried. But ill try the software you suggested.

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