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Old 17th February 2010, 10:15 AM   #1
el`Ol is offline el`Ol  Germany
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Default time alignment in horn loudpeakers

Hello all!

I am working on a concept for very invisible corner speakers.
The woofer is chosen, it will be this SEAS, crossed at 1 kHz.
THE ART OF SOUND PERFECTION BY SEAS - H1488-08 L16RNX
The tweeter will have a constant directivity horn. High SPL is not necessary, so virtually every 1" driver will do it down to 1 kHz.
Perfect time alignment is not possible of course, so an other solution will have to be found. With an Eighteensound horn and a Celestion driver one would have an offset of the half wavelength at the crossover frequency.
My question:
Is this essential, or can the phases be adjusted, so that shorter horn/driver combinations would do it, too?

Oliver
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Old 17th February 2010, 11:38 AM   #2
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Imho, that depends on two things or maybe three.

Can you get that setup to create a proper stereo image?

Can you hear the time/phase difference?

Some people feel that flat amplitude response is paramount and phase relationships of this sort are either inaudible or of less significance.

With that woofer, I would be concerned about getting the huge peak in the HF end of the response controlled and cut off, otherwise with a "normal" crossover, that area will be audible...

The question is what will the "offset" actually be after you apply the xover to it? The xover will have some delay and phase shift depending upon what xover you employ - the physical relationship that you mention is only part of the story. And, if it is a half wavelength, perhaps you can flip the phase of one driver and have a zero wavelength difference?

What's the physical distance that a half wavelength at 1kHz is equal to?

Can you not physically compensate for that??



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Old 17th February 2010, 12:59 PM   #3
el`Ol is offline el`Ol  Germany
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I am not concerned about phase relationship, I just don't want to have a cancellation at the crossover point. I thought with the half wavelength (17.2 cm) I can use the same crossover I would have used otherwise, just with one polarity reversed. Physical compensation is impossible, woofer and horn have to be mounted on the same baffle. Placement of the woofer will be in a way that enclosure and walls work like a horn up to 1 kHz, so this will reduce the danger of getting problems with the giant resonance peak.
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Old 17th February 2010, 01:21 PM   #4
Pano is offline Pano  United States
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Quote:
Originally Posted by bear View Post
The xover will have some delay and phase shift depending upon what xover you employ - the physical relationship that you mention is only part of the story.
Amen, brother Bear. You have to know the phase shift of the crossover.

Quote:
Originally Posted by el`Ol View Post
I am not concerned about phase relationship, I just don't want to have a cancellation at the crossover point.
Then, in fact, you are worried about the phase.
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