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Old 14th December 2012, 10:20 PM   #31
xrk971 is offline xrk971  United States
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endia,
Thanks for the drawings! Planet10 actually had made a pdf too but it is buried in the foam core thread. I have made the Cornus with both exaggerated square corners internally (the 20 inch) and also very round spirals on the micro 14 incher. The square shaped with rounded corners was devised by Daniel Ciesinger to reduce the number of cuts they had to make in the wood channels. Since we use foam core board, it is easy to make lots of cuts for a more rounded spiral. I think having the more square shape will help to filter the higher frequencies from coming out the horn. But in practice, the more square one is still quite smooth. If you really want to low pass the sound, make sharp corners.
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Old 14th December 2012, 10:31 PM   #32
endia is offline endia  Turkey
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xrk971, thank you..
i also started to read foam core thread.
this will be my first speaker project, what do you think about my 3" drivers for 20"?
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Old 14th December 2012, 10:38 PM   #33
xrk971 is offline xrk971  United States
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3 in driver should work in 20 in. Scale depth of channel to allow throat area to match driver piston area.
Good luck.
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Old 14th December 2012, 10:41 PM   #34
endia is offline endia  Turkey
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i hope so,
thanks for helps, xrk971.
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Old 14th December 2012, 11:00 PM   #35
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Originally Posted by xrk971 View Post
Cal,
When are you gonna start on speaker set #34 with your 5.25 in drivers?
Ummm...

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Old 15th December 2012, 12:06 AM   #36
gpapag is offline gpapag  Greece
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George,
Thank you for the kind words but...
Regards,
Xrk971

(there was a comma after the inventor )

xrk971 I am too for alternative, cheap, easy to work, having some interesting properties materials for speakers. The diy joy for never grown-up boys is the experimentation and learning, not the cash spending.

Regarding positive justification of adding front horn loading to a rear horn loaded driver and some other technical questions asked already regarding cornu multiple horn, here is a series of 3 articles where one can find a lot of relevant answers (bifurcation, equal mouths, throat size effect, rear chamber importance, horn path bending effects ect)and valuable explanations.

http://www.metaleater.narod.ru/Dinsdale_Horns_1.pdf
http://www.metaleater.narod.ru/Dinsdale_Horns_2.pdf
http://www.metaleater.narod.ru/Dinsdale_Horns_3.pdf

Planet10 has wisely noted that with cornu, the lack of baffle step effect and the “on the wall” placement, makes things easy for the bass region, but that the rear horn help should start where the unattended driver’s front radiation –frequency wise – diminishes.

I fully agree with this, but on this important point (integration of front to rear output) I guess, one has to face the complication of the added effect the vibrating large panel surface has on the overall sound.

The “big sound” effect (as I read) with these speakers reminds me of the omni’s same effect. It has to do with the increased amount of indirect sound that is emitted and reaches our ears. This adds "space" to the music (I like it)

I can’t wait till I put my hands on this project!

George
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Last edited by gpapag; 15th December 2012 at 12:13 AM.
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Old 15th December 2012, 01:55 AM   #37
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The “big sound” effect
Yup.
Quote:
I can’t wait till I put my hands on this project!
Me too, I like when those 'in the know' get involved. George, I hope you get the same satisfaction.

Cheers.
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Old 15th December 2012, 02:22 AM   #38
xrk971 is offline xrk971  United States
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George,
Thanks for the three articles on horn theory and design - very helpful info. I have always wondered if it was the big front baffle acting as a passive radiator that was contributing to the signature of the sound. I think the effect should be more pronounced with the foam core face than plywood faced variants.
Xrk971
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Old 15th December 2012, 04:11 PM   #39
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The diy joy for never grown-up boys is the experimentation and learning, not the cash spending.
Very well put, should become your tagline for 2K13.
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Old 15th December 2012, 11:15 PM   #40
gpapag is offline gpapag  Greece
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Yup.

George, I hope you get the same satisfaction.
I will. The mental exercise has started already (“while counting sheep” as you say). Thank you

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Originally Posted by xrk971 View Post
George,
I have always wondered if it was the big front baffle acting as a passive radiator that was contributing to the signature of the sound. I think the effect should be more pronounced with the foam core face than plywood faced variants.
Xrk971
Xrk971,
A baffle vibrating when excited through the frame of an attached speaker motor,is nothing like the defined and predicted action of a passive radiator.
I will not use the term “chaotic” (which is not) but the vibration modes become very complex and the resulting acoustic output even more so.
I have a lot of reservations as to whether vibrating panel speakers have been developed based on true analysis rather than experimentally decided “best acoustic results” (not that I reject such an approach).
For me, a panel formed from three layers of corrugated paper (layers oriented 90d/0d/90d for structural integrity and deformation symmetry)glued together with acrylic silicon, provides the quietest reference to which I compare other panel materials/constructions.
Discussion on what materials to build speakers out of


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Very well put,
Thank you jacco. I assume you agree on the “never grown-up”

George
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