Continuing discussion/questions on Directivity

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rascal

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Continuing discussion/questions on Directivity
« on: 7 Sep 2015, 08:09 pm »
Hello,

I was reading this fascinating thread on Duke's Audiokinesis circle here http://www.audiocircle.com/index.php?topic=136626.0, and what caught my eye was Dave post on http://www.audiocircle.com/index.php?action=post;board=181.0

Can someone "esplain"  :lol: on princeton study- does that mean Sander speaker is better than Gedlee nathan? (I recall Gedlee nathan were top in older study).

Also when I look at stereophile measurements on loudspeakers- besides impedance variation (load on amp), and looking  at +- dB range within listening angle, anything else I can scan to see if it is good (on measurements) at least? One of folks told me he qualifies speakers if (measurement) variance is 2dB within listening window..is that a good metric :scratch:

Thoughts or Feedback?

I am still learning, so thank you for patience  :duh:

poseidonsvoice

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Re: Continuing discussion/questions on Directivity
« Reply #1 on: 7 Sep 2015, 08:59 pm »
See my post here:

http://www.audiocircle.com/index.php?topic=136205.msg1448634#msg1448634

The Princeton study ranks them based on the *highest average DI*,  so ESL's will always rank at the top. What you want to do is look at the polar plot visually. Does it look like a perfect rectangle? What frequency does it start at? Does it start at 1khz or below or is it much higher? Is it constant for several octaves, or does it have several "pinched areas" indicating multiple poorly designed crossover points with varying directivity and hence poorer directivity control. What frequency does it end at? 10khz or less? (More is fine but I think at least 8-10khz is wonderful). In that study the Nathan was "so,so" and hence taken off the market. In comparison the Gradient design and Genelec designs were much better IMHO. The Nathan in no way compares to the newer Abbey(c), NA12 or NS15 if all we are talking about is polar plots and horizontal off axis response/directivity control.

See here for more thoughts on this subject, Nyal did a WONDERFUL job explaining different directivities of different loudspeaker types (several links and all are good!):

http://www.acousticfrontiers.com/category/blog/acoustics/speaker-directivity/

Best,
Anand.