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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, 05:15 PM   #21
Galu is offline Galu  Scotland
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Quote:
Originally Posted by picowallspeaker View Post
Different reality perception & organization
Same wave physics!
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Old 12th June 2019, 05:31 PM   #22
emosms is offline emosms  Bulgaria
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Originally Posted by Galu View Post
If I'm reading it correctly, the narrowed vertical dispersion would prevent treble energy being wasted through being directed towards the ceiling or the floor.
So we only have PA efficiency?

More concerned about the interference of mids and twitter around the xover frequency and all the related deffects.
- could a more straightforward vertical dispersion reduce the interference with the mids dispersion? (the driver mounted bellow)

It is also interesting what is the efect of the more wide / uniform lateral dispersion to the stereo imaging.

// all the above about the JBL type slanted acoustic 'lens'.

Last edited by emosms; 12th June 2019 at 05:37 PM.
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Old 12th June 2019, 06:22 PM   #23
Charles Darwin is offline Charles Darwin  United Kingdom
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I assume that an acoustic lens does what it does with the help of diffraction.

Diffraction is not a good idea and should be avoided.
Which is probably why you don't see them much anymore.
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Old 12th June 2019, 06:23 PM   #24
Galu is offline Galu  Scotland
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The papers in the link below agree with the wider dispersion mentioned by JMFahey.

Horns are very directional at high frequencies, and an acoustic lens widens the dispersion when used in conjunction with a horn rather than with a point source such as a dome tweeter.

Doesn't give an answer to your questions though!

Acoustic Lens Technology – the research continues | Evangel Ric Lapore

Last edited by Galu; 12th June 2019 at 06:30 PM.
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Old 12th June 2019, 06:27 PM   #25
Galu is offline Galu  Scotland
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Quote:
Originally Posted by Charles Darwin View Post
I assume that an acoustic lens does what it does with the help of diffraction.
Not diffraction Charles, but refraction. Check out the papers in my previous post.
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Old 12th June 2019, 06:44 PM   #26
TBTL is offline TBTL  Germany
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Quote:
Originally Posted by Galu View Post
If I'm reading it correctly, the narrowed vertical dispersion would prevent treble energy being wasted through being directed towards the ceiling or the floor.
The slanted plate style acoustic lens only works in the horizontal direction.


Here is some background information: https://www.tnt-audio.com/clinica/acoustic_lens.pdf

Last edited by TBTL; 12th June 2019 at 06:48 PM.
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Old 12th June 2019, 06:46 PM   #27
emosms is offline emosms  Bulgaria
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It is either reflection or diffraction, or probably both...

Refraction is more related to optics - going from a medium to a medum. f.ex. glass to air, water to air and vice versa.
It closer resembles a transparent optics lens.

- Reflection, Refraction, and Diffraction

Anyway, have to find a guideline on how to design this JBL type of lens.
Then I can decide.
Not a problem to make the parts from acrylic or HPL.
But how to design this?

p.p. I found an article praising the slanted lens design. Says it is "the best" solution for HF.
At the end, it says it is not seen nowadays, mostly because of how it looks .
But cant find the exact same article

Last edited by emosms; 12th June 2019 at 06:52 PM.
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Old 12th June 2019, 06:48 PM   #28
emosms is offline emosms  Bulgaria
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Quote:
Originally Posted by TBTL View Post
The slanted plate style acoustic lens only works in the horizontal direction.
What about the vertical dispersion diagram from the JBL paper?
It shows kind a narrowing the 'beam' in a vertical crossection.
Not really parallel, but..
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Old 12th June 2019, 06:51 PM   #29
TBTL is offline TBTL  Germany
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The JBL image of post #6 shows that the vertical dispersion is narrow as is expected from a narrow horn. The horizontal dispersion is wide, like explained in the pdf in post #26.
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Old 12th June 2019, 07:33 PM   #30
Galu is offline Galu  Scotland
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Quote:
Originally Posted by emosms View Post
It is either reflection or diffraction, or probably both...
Refraction is more related to optics - going from a medium to a medum. f.ex. glass to air, water to air and vice versa.
It closer resembles a transparent optics lens.
It is most definitely refraction.

Refraction relates to the change in speed when a wave travels from one medium into another.

Just as light slows down when it enters glass, sound waves slow down when they enter an acoustic lens. See my earlier link for the full explanation.

P.S. My link gives the same paper as TBTL's link.

Last edited by Galu; 12th June 2019 at 07:41 PM. Reason: Added P.S.
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