Problems with Waterfall measurements - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 5 Old 01-19-17, 06:52 PM Thread Starter
Shackster
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Problems with Waterfall measurements

Is there anything that I could have messed up with my measurement equipment that would cause a very large decay time in the high frequency ranges?

My waterfall 5k and above shows that sounds stay in the room forever and never go away. What could cause this?

The purple was a previous measurement and the red is the new reading.

Something is obviously wrong but I don't know what--help!

The top one is what I was seeing before and now I am getting the bottom one.

(both images are left speaker + sub with no EQ)


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post #2 of 5 Old 01-20-17, 11:18 AM
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Wayne Myers
 
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Re: Problems with Waterfall measurements

Quote:
laserstl wrote: View Post
Is there anything that I could have messed up with my measurement equipment that would cause a very large decay time in the high frequency ranges?

My waterfall 5k and above shows that sounds stay in the room forever and never go away. What could cause this?

The purple was a previous measurement and the red is the new reading.

Something is obviously wrong but I don't know what--help!

The top one is what I was seeing before and now I am getting the bottom one.

(both images are left speaker + sub with no EQ)


HF System Noise = Hiss = White Noise. What have you changed that might have introduced it? It can result from an introduced ground loop, for instance. Or a change in your gain structure. It might have been there all along, only at a much lower level.
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post #3 of 5 Old 01-20-17, 12:14 PM
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Re: Problems with Waterfall measurements

AudiocRaver is much more knowledgeable than I, but just in case, I have seen similar ringing in the HF when the sample rate for the pc "Play Back" device was not set to the same bit depth and sample rate as REW. Rew is usually 24/48. Its easy enough to check and may be worth a quick look.
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post #4 of 5 Old 01-20-17, 12:35 PM
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Wayne Myers
 
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Excellent suggestion, good catch, John.
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post #5 of 5 Old 01-20-17, 02:19 PM Thread Starter
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Quote:
John Stewart wrote: View Post
AudiocRaver is much more knowledgeable than I, but just in case, I have seen similar ringing in the HF when the sample rate for the pc "Play Back" device was not set to the same bit depth and sample rate as REW. Rew is usually 24/48. Its easy enough to check and may be worth a quick look.
Thanks for the suggestion--I will check on that.


The other strange thing is that this effect is greatly reduced when I change the sweep length from 512 to 256. So I think it is something weird going on in my measurement or microphone rather than noise in the room/system.
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