Distortion graph? - Home Theater Forum and Systems - HomeTheaterShack.com

Old 09-10-08, 07:01 PM Thread Starter
Senior Shackster
bjs

Join Date: Jun 2008
Location: Vancouver, BC
Posts: 162
Distortion graph?

I find non-linear distortion as objectionable in many ways as linear distortion so was pleased to discover that REW can measure harmonic distortion based on a sine wave input.

I'm actually trying to do a range of frequencies and would like to see the combined results graphically. Conceptually that means sweeping the input frequency over a range and, for each frequency, plotting the relative strengths of the fundamental and its harmonics (which is currently captured in the tabular form).

Can REW do this? If not could it be added?
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Old 09-10-08, 09:41 PM
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Anthony

Join Date: Oct 2006
Location: Virginia
Posts: 2,213
Re: Distortion graph?

As far as I know it's just the output when an input signal is approximately a sine wave. I know approximate, because, I can whistle a tone and hold it for a few seconds and it measures the distortion That's how I discovered this feature.

If there's a way to slow sweep or log individual points, I dont know how. Maybe John will chime in on how feasible this might be.
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Old 09-11-08, 03:26 AM
REW Author

John

Join Date: Apr 2006
Location: UK
Posts: 6,307
Re: Distortion graph?

It is on the list for a future release
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Old 09-11-08, 04:07 PM
Elite Shackster

Josh

Join Date: May 2007
Location: Louisville, KY
Posts: 2,431
Re: Distortion graph?

John,
That's good news. What about the possibility of doing mulitple sine waves at the same time like IMD testing? Like choosing to output 20hz, 32hz, and 50hz at the same time?
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Old 09-12-08, 01:14 PM
REW Author

John

Join Date: Apr 2006
Location: UK
Posts: 6,307
Re: Distortion graph?

Most things are possible, but there would need to be enough demand and a good reason, writing REW is a spare time activity and spare time is a rare thing nowadays
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Old 09-12-08, 06:51 PM Thread Starter
Senior Shackster
bjs

Join Date: Jun 2008
Location: Vancouver, BC
Posts: 162
Re: Distortion graph?

As I recall from tests I did years ago, speakers that measured well on standard THD tests also did well on IM tests so it might not be worth a lot of effort.
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