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Old 28th October 2011, 09:38 AM   #1601
graaf is offline graaf  Poland
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Quote:
Originally Posted by DDF View Post
Increasing early reflection density with speaker listening would have a similar effect and allow more of the direct sound to dominate over the later reverb, in theory increasing intelligibility. Using early diffraction, there is less tonal distortion due to the early reflection.
very interesting! thank You!
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Old 28th October 2011, 10:13 AM   #1602
graaf is offline graaf  Poland
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I have recently found an interesting paper by P.W. Klipsch summarizing His extensive tests:
Stereo Geometry Tests

excerpt:
Quote:
Previous experiments by the writer have shown that the stereo effect becomes marginal at a distance about 1.5 times the spacing of the flanking speakers, which is the prime purpose for wide speaker spacing.
Klipsch argued for angles larger than typical audiophile equilateral triangle of today because "stereo in the sense of reproducing the original spatial relationships requires larger angles. Large angles are best served with flanking speakers spaced to the corners, even to the extent of using the long wall of an oblong room"

interestingly, larger angles is also what one gets with Beveridge placement, Beveridge was able to propose His own different kind of stereo geometry, taking the speakers out of the corners because of narrow line source characteristics of His speakers
in contrast Klipsch was working with highly directive speakers - therefore to achieve the same level of homogeneity He had to put the speakers in the corners with significant toe-in (He advocated around of 45 degrees of toe-in)
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Old 30th October 2011, 10:44 PM   #1603
Elias is offline Elias  Finland
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Quote:
Originally Posted by graaf View Post
I have recently found an interesting paper by P.W. Klipsch summarizing His extensive tests:
Stereo Geometry Tests

excerpt:


Klipsch argued for angles larger than typical audiophile equilateral triangle of today because "stereo in the sense of reproducing the original spatial relationships requires larger angles. Large angles are best served with flanking speakers spaced to the corners, even to the extent of using the long wall of an oblong room"

interestingly, larger angles is also what one gets with Beveridge placement, Beveridge was able to propose His own different kind of stereo geometry, taking the speakers out of the corners because of narrow line source characteristics of His speakers
in contrast Klipsch was working with highly directive speakers - therefore to achieve the same level of homogeneity He had to put the speakers in the corners with significant toe-in (He advocated around of 45 degrees of toe-in)

Isn't it true that Blumlein, the inventor of stereo, suggested +-45 degrees stereo triangle ? Just see Blumlein's stereo microphone with crossed dipoles !

In practise, however, psychoacoustics strikes back, and a hole in the middle can be perceived with too wide base angle. Probably for this reason usually narrower angle is used.

I don't know where +-30 degrees comes from ? Maybe equilateral just looks nice ?


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Old 31st October 2011, 07:37 AM   #1604
graaf is offline graaf  Poland
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Quote:
Originally Posted by Elias View Post
Isn't it true that Blumlein, the inventor of stereo, suggested +-45 degrees stereo triangle ?
Klipsch and also Jordan advocate for even wider angles than 45 degrees

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Originally Posted by Elias View Post
a hole in the middle can be perceived with too wide base angle.
BTW have You experienced a hole in the middle with Your pillowed bipolar setup?
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Old 31st October 2011, 08:30 AM   #1605
graaf is offline graaf  Poland
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Quote:
Originally Posted by graaf View Post
Klipsch and also Jordan advocate for even wider angles than 45 degrees
ps.

as to Jordan's linear array system He recommended that the stereo base could be as much as 15 feet wide with very flat loudspeakers wall mounted and toed in 60 degrees so their axis cross well in front of the listener area
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Old 31st October 2011, 09:33 AM   #1606
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Presumably the 'hole in the middle' disappears once the arrangement comes to resemble a large pair of headphones.
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Old 31st October 2011, 09:36 AM   #1607
graaf is offline graaf  Poland
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Originally Posted by CopperTop View Post
Presumably the 'hole in the middle' disappears once the arrangement comes to resemble a large pair of headphones.
yes, perhaps, actually most of listeners of my bipolar boxes had impression of a kind of externalised headphones sound

I wonder what could be the real cause of the 'hole in the middle' then?
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Old 31st October 2011, 11:30 AM   #1608
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I think the hole in the middle is just the typical loss of the center image when path lengths aren't exact. There is also the question of how much well centered material the recording contains. Classical music with spaced mics might be weak in this area. There are a lot of early pop stereo recordings that use left center and right as the only image locations. They would make a good test (I'm listening to a "Best of Marvin Gaye" these days, which would suit.)

Klipsch was mostly following the recommendations from the Bell Labs experiments that he liked well enough to reprint and distribute. If you must put your speakers in opposite corners then adding a center can be helpful. Note that for a period of time he was advocating a center channel connection that used out-of-phase difference information, until that error was pointed out to him. Even the greats make mistakes.

David S.
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Old 31st October 2011, 02:47 PM   #1609
Pano is offline Pano  United States
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Test your center image with mono recordings. Simple. I happen to like the sound of 2 channel phantom mono better than single speaker, FWIW.
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Old 21st November 2011, 11:09 AM   #1610
graaf is offline graaf  Poland
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from an article by Alvin Foster:


Quote:
Harmonic and IM distortion, phase response/time lag, transient response, squarewave reproduction, decay time, etc., measured in my tests and others', have proven to be unreliable indicators of a loudspeaker's playback quality. I cited, among others, the definitive research of Salmi and Wickstrom, Toole, and at Bose, all of which concluded that such distortions pale in significance to frequency response and dispersion pattern.
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