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Old 27th January 2010, 09:47 PM   #171
SunRa is offline SunRa  Romania
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Thank you for your clarifications Dr. Geddes, much appreciated!

I can no see that higher resolution is preferable. The 18 Sound plot looks very clean by comparison, espeaceally in the horizontal plot. For example, there is nothing I can identify with HOM and something tells me this is rather due to the lack of resolution rather than the lack of HOM.
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Old 28th January 2010, 12:37 AM   #172
gedlee is offline gedlee  United States
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Originally Posted by gfiandy View Post
Hi Earl,

I am interested to know if you have done polar distortion measurements. If you have does the distortion track with level or do you see genuinly different levels of distortion at different angles?

Thanks for any information you might have, I am just curious about this.

Regards,
Andrew
I don't do distortion measurements on loudspeakers. They have never been shown to correlate with subjective perception, so its really a waste of time. People do them because they can, not because they should.
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Old 28th January 2010, 01:54 AM   #173
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Originally Posted by gedlee View Post
I don't do distortion measurements on loudspeakers. They have never been shown to correlate with subjective perception, so its really a waste of time. People do them because they can, not because they should.
Isn't the same true for polar maps? They are easy to measure but they don't correlate with subjective perception.
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Old 28th January 2010, 05:31 AM   #174
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Originally Posted by SY View Post
zilch: Do you have an actual technical argument or are you just trolling?
At this time, just a question:

The top octave appears to be missing. Am I misreading the plots, or have I overlooked an element of the rationale here...?

Last edited by ZilchLab; 28th January 2010 at 05:33 AM.
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Old 28th January 2010, 05:41 AM   #175
FrankWW is offline FrankWW  Canada
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Huh?!

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Isn't the same true for polar maps? They are easy to measure but they don't correlate with subjective perception.
Why'd you buy your Nathans?
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Old 28th January 2010, 05:47 AM   #176
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Did someone do a study on polar maps and subjective impressions? I haven't seen much even written about polar mapping.

Dan
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Old 28th January 2010, 12:28 PM   #177
gedlee is offline gedlee  United States
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Originally Posted by markus76 View Post
Isn't the same true for polar maps? They are easy to measure but they don't correlate with subjective perception.
No, not at all! I find the polar maps to correlate very well with perception. This has not been quantified like the distortion stuff however.
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Old 28th January 2010, 12:30 PM   #178
gedlee is offline gedlee  United States
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Originally Posted by dantheman View Post
Did someone do a study on polar maps and subjective impressions? I haven't seen much even written about polar mapping.

Dan
Floyd's work is close, but he simplifies the maps down to a few lines. I prefer the higher data density.

But there have been several studies on nonlinear distortion and they have all shown the same thing - no correlation.
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Old 28th January 2010, 01:23 PM   #179
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Why'd you buy your Nathans?
Why not? Is there a cheaper, better performing HOMless speaker out there?

We're talking about how polar maps correlate to perception. It is out of question that the indirect sound field does affect perception. But then, distortion affects our perception too

Best, Markus
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Old 28th January 2010, 03:41 PM   #180
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Originally Posted by gedlee View Post
Floyd's work is close, but he simplifies the maps down to a few lines. I prefer the higher data density.

But there have been several studies on nonlinear distortion and they have all shown the same thing - no correlation.
In the "Predicting Listener Preference from Measurements," section of Toole's book and in many other places looking at pro speakers there is a "Directivity Index" given in decibels usually scaled from 0-10 dB or something like that. Is that scaling how far down the response would be at 45 degrees? I don't actually see anything else about polar response in the data. There are indication of the polar response, but nothing direct. There is measurements at the "Listening Window", "Early Reflections", "Directivity Index" and "Sound Power" given, but no polar response graphs.

Thanks again,

Dan
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