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Multi-Way Conventional loudspeakers with crossovers

tweeter with blinds-like waveguide
tweeter with blinds-like waveguide
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Old 12th June 2019, 01:19 PM   #1
emosms is offline emosms  Bulgaria
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Default tweeter with blinds-like waveguide

Hi, I read an article explaining this type of old fashioned "waveguide" some time ago:
- smth. like window blinds right in front of the twitter.

It consists of horizontal "boards" at an angle of mby 45 degrees. Extended in front of the panel.

How is that called? I want to find the article and re-read the explanation about it.

This is an example of it, but there are slightly different shapes as well.

Click the image to open in full size.

Regards

Last edited by emosms; 12th June 2019 at 01:25 PM.
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Old 12th June 2019, 01:23 PM   #2
Galu is online now Galu  Scotland
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Acoustic lens tweeter.
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Old 12th June 2019, 01:24 PM   #3
JRKO is offline JRKO
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Do you mean like the jbl lens?
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Old 12th June 2019, 01:30 PM   #4
emosms is offline emosms  Bulgaria
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Yes, what it does?
Any relation to the soundwave interference with the lower band (mids)?

Or "constant directivity", on and off axis?
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Old 12th June 2019, 01:39 PM   #5
Galu is online now Galu  Scotland
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Quote:
Originally Posted by emosms View Post
Yes, what it does?
Disperses the sound to stop beaming of high frquencies.
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Old 12th June 2019, 01:50 PM   #6
Galu is online now Galu  Scotland
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Diagrams showing the vertical and lateral dispersion patterns.
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Old 12th June 2019, 01:56 PM   #7
TBTL is offline TBTL  Germany
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I guess it works similar to an optic lens. The sloped plates cause the speed of sound (in forward direction) to be lower than in air. In optics, glass does the same to the speed of light. These lenses have a similar shape to a negative optic lens. If they are mounted to a horn (= point source located at the compression driver), I expect them to widen the dispersion.

Last edited by TBTL; 12th June 2019 at 02:02 PM.
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Old 12th June 2019, 02:04 PM   #8
Galu is online now Galu  Scotland
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Quote:
Originally Posted by TBTL View Post
Judging by the shape, it should widen the dispersion.
The function is to control the dispersion of high frequencies. More accurately it converts a single point sound source into a parallel wavefront - similar to the way a convex lens can convert the light from a point source into a parallel beam.

P.S. I'm basically agreeing with you TBTL!

Last edited by Galu; 12th June 2019 at 02:14 PM. Reason: Added the P.S. Changed quote to 'widen'
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Old 12th June 2019, 02:06 PM   #9
TBTL is offline TBTL  Germany
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I made a mistake, a negative lens should widen the dispersion of a point source. However, I think it does not convert the expanding wavefront of a point source into a parallel wavefront - that would require a positive lens and that would narrow the dispersion.
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Old 12th June 2019, 02:22 PM   #10
Galu is online now Galu  Scotland
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I mean like this.
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