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Old 1st May 2013, 06:41 PM   #11
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Originally Posted by markus76 View Post
If the rear wave of an OB is considered detrimental then why use OBs in the first place?
Constant Directivity across a very wide frequency band can be achieved, and no box to cause colorations.
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Old 1st May 2013, 07:10 PM   #12
adason is offline adason  United States
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well said Stig
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Old 1st May 2013, 07:31 PM   #13
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Originally Posted by StigErik View Post
Constant Directivity across a very wide frequency band can be achieved, and no box to cause colorations.
The former is achieveable with other methods too. As far as I know the latter has never been shown to be a significant factor.
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Old 2nd May 2013, 03:56 PM   #14
gedlee is offline gedlee  United States
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Originally Posted by ra7 View Post
So Stig, if you are going to kill off all the rear radiation, what is advantage of an OB compared to a sealed woofer? Directivity in the lower octaves?
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Originally Posted by markus76 View Post
If the rear wave of an OB is considered detrimental then why use OBs in the first place?
Better LF directivity. There is no other way to get LF directivity with only one speaker. If this is important or not is the issue.
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Old 2nd May 2013, 03:59 PM   #15
gedlee is offline gedlee  United States
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Originally Posted by StigErik View Post
An other is that the dipole is a velocity source instead of a pressure source; properly placed it will excite the room modes less.
A velocity source, yes, but less room mode excitation than a monopole, that is a common misconception, but it is incorrect. Put either at the their particular "best" locations and the room mode excitation will be about the same. This "best" location is different for the two types however.
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Old 2nd May 2013, 04:04 PM   #16
adason is offline adason  United States
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Originally Posted by markus76 View Post
The former is achieveable with other methods too. As far as I know the latter has never been shown to be a significant factor.
markus76, box colorations were always a factor for me
when I heard good open baffle speakers (audio artistry beethoven), I heard no box, since then I never went back, no matter how well that box is made, there is still some resonant character to the sound for me, call it boxy sound if you will, I always hear it
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Old 2nd May 2013, 04:05 PM   #17
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Default out of my league

Wow, I really have to get with the program regarding acoustics. You guys sound like physicists! ha ha! maybe there is reference material i should start reading.
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Old 2nd May 2013, 04:06 PM   #18
gedlee is offline gedlee  United States
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Originally Posted by markus76 View Post
The former is achieveable with other methods too. As far as I know the latter has never been shown to be a significant factor.
Quite correct on your second point and I have done these tests. box coloration is a fallacy unless the box is junk.

And dipoles are not, in general, constant directivity across a wide bandwidth unless the drivers are very small. Otherwise the directivity will narrow with frequency just as it does in a close box. You do get some bandwidth of constant directivity - at a fairly low DI - but it is not "very wide". These are the old "Dipoles are better" fallacies.

Dipoles have a small directivity advantage at LFs but a BIG efficiency disadvantage at these same frequencies.
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Old 2nd May 2013, 04:10 PM   #19
gedlee is offline gedlee  United States
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Originally Posted by adason View Post
call it boxy sound if you will, I always hear it
I am sure that is true as long as you can "see" it as well.

It can't be measured, I've tried, and I don't hear it.
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Old 2nd May 2013, 04:30 PM   #20
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Originally Posted by adason View Post
markus76, box colorations were always a factor for me
when I heard good open baffle speakers (audio artistry beethoven), I heard no box, since then I never went back, no matter how well that box is made, there is still some resonant character to the sound for me, call it boxy sound if you will, I always hear it
I think the difference in the indirect sound is causing such a sensation not the box itself. A blind listening test would shed some light on the matter.
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