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-   -   The construction of a multicell horn (http://www.diyaudio.com/forums/multi-way/136964-construction-multicell-horn.html)

Petter Persson 20th January 2009 08:13 PM

The construction of a multicell horn
 
I'll try my best to inspire and to show to you that everything is possible. To do a multicellular horn takes a while due to all different moments but they are all kind of nice and it feels good to see the horn grow with every hour of work.

These horns are NOT a Altec 1505B copy. They are pure exponential with a flare frequency of 183 Hz, the same, or at least what was my and reVintages intentions bacause the throat flare in JBL 2441 and 2445.

The horns are built out of 3 mm Baltich Birch plywood, filled with polyester and the outher sides are covered with polyester and glass fibers.

Enjoy:cool:

Petter Persson 20th January 2009 08:14 PM

8 Attachment(s)
Construction of a mold

http://proxy1.pixbox.se/arkivet/synl...0/22887580.jpg


http://proxy1.pixbox.se/arkivet/synl...0/22887582.jpg


Was later copied so the mold became symmetrical

http://proxy1.pixbox.se/arkivet/synl...0/22887757.jpg


http://proxy1.pixbox.se/arkivet/synl...0/25793040.jpg

http://proxy1.pixbox.se/arkivet/synl...0/22887606.jpg

Petter Persson 20th January 2009 08:15 PM

6 Attachment(s)
Good start:)

http://proxy1.pixbox.se/arkivet/synl...0/22887765.jpg


Some help from a friend

http://proxy1.pixbox.se/arkivet/synl...0/22887766.jpg


http://proxy1.pixbox.se/arkivet/synl...0/22887603.jpg


http://proxy1.pixbox.se/arkivet/synl...0/23342746.jpg


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http://proxy1.pixbox.se/arkivet/synl...0/23342751.jpg

Petter Persson 20th January 2009 08:16 PM

10 Attachment(s)
So the cells have zero edge width at their beginning.

http://proxy1.pixbox.se/arkivet/synl...0/23490399.jpg

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http://proxy1.pixbox.se/arkivet/synl...0/23507030.jpg

Petter Persson 20th January 2009 08:18 PM

6 Attachment(s)
One side was taped

http://proxy1.pixbox.se/arkivet/synl...0/23799970.jpg

And filled with polyester

http://proxy1.pixbox.se/arkivet/synl...0/23799971.jpg

http://proxy1.pixbox.se/arkivet/synl...0/23799973.jpg

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Petter Persson 20th January 2009 08:20 PM

9 Attachment(s)
Construction of adapter

http://proxy1.pixbox.se/arkivet/synl...0/23800035.jpg

http://proxy1.pixbox.se/arkivet/synl...0/23820190.jpg

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http://proxy1.pixbox.se/arkivet/synl...0/24099509.jpg

Petter Persson 20th January 2009 08:21 PM

4 Attachment(s)
X-mas:cool:

http://proxy1.pixbox.se/arkivet/synl...0/25163214.jpg




Finish!

Sorry for the filter, the layout is just preliminary and will be changed.

http://proxy1.pixbox.se/arkivet/synl...0/25793483.jpg

http://proxy1.pixbox.se/arkivet/synl...0/25793484.jpg

http://proxy1.pixbox.se/arkivet/synl...0/25793485.jpg


The crossover at 500 (12 db electrical) and 3000 Hz (6 dB electrical)

Sounds like heaven:D

If you have any questions/comments please post them and I'll try to answer.



Thanks! / Petter, Sweden

WithTarragon 20th January 2009 08:40 PM

Excellent Work!!!!!!!!

That was a very nice project. Very, very nice.
I was a bit confused on the throat adapter's construction. I may just need to look at it more closely.

Have you had a chance to make any acoustic measures of the horn, especially the polars?

Thank you very much for posting this

Helmuth 20th January 2009 09:26 PM

Looks great Petter,:smash:

Thanks for sharing your solution how to construct the horn.
:worship:

bear 21st January 2009 03:10 AM

Very nice work...

If you measure them I'll be curious to see what the real F3 freq works out to be (sans xover), given the mouth size and the flare rate being 183Hz...

I have Altec 1003s, 803s and 203s here to play with... I like that they go to <300Hz. Makes the xover to midbass much better, imho.

One of the real problems with any horn is that there is significant energy there, and the sides of the horn, especially with the thin walls of the multicells (or anything made with thin wood or steel) are not sufficiently stiff... I've had to reinforce the walls of my 203s (for example) which makes a world of difference.

Among the best of the WE and Altec multicells are the ones that are "Tar Filled" - a big hunk of heavy dried asphalt/tar that was moulded around the whole thing... dead and heavy.

So I was wondering what you did about that, if anything with your wood horns. I did notice what looked like some fiberglass over the cells of the completed horn... hard to tell from the pix what it is for?

Btw, they look wonderful!
Nice work...

_-_-bear


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