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demon
11-25-2008, 08:26 AM
i got a pair of 236oA horns the other day, as some of you might know, and i have the following problem:
http://i303.photobucket.com/albums/nn153/mikeysound/P1080323w.jpg
http://i303.photobucket.com/albums/nn153/mikeysound/P1080325w.jpg
http://i303.photobucket.com/albums/nn153/mikeysound/P1080327w.jpg

as you can see, there are warps (and warp-caused holes!) right at the beginning of the throat of the second part of the horn.
what to do??
:confused:
thanks for help!!
cheers--
mikey

johnaec
11-25-2008, 08:38 AM
Please post some more pictures from a greater distance that shows this area more in context. And maybe you could also post some pictures of what the good one is supposed to look like.

John

Earl K
11-25-2008, 09:01 AM
as you can see, there are warps (and warp-caused holes!) right at the beginning of the throat of the second part of the horn.
what to do??

As John mentioned , better pictures would be helpfull. To most casual viewers, the pictures you've shown are disorienting .

- Anyways, you've shown the end of the metal entry throat that opens into a diffraction slot . I have one here .

It appears to my eyes that someone ( maybe even JBL ) has tried to cover-up a very bad metal casting ( the holes in the metal ) by applying a self-sticking piece of black pvc inside the throat area . A loosening of the adhesive at the edges ( of the black pvc ) would give the "look" that you've displayed .

If my conjecture is correct , simply glue it back down and call it good .

<> cheers

hjames
11-25-2008, 09:16 AM
i got a pair of 236oA horns the other day,
as some of you might know, and i have the following problem:
as you can see, there are warps (and warp-caused holes!)
right at the beginning of the throat of the second part of the horn.
what to do??
:confused:
thanks for help!!
cheers--
mikey

Bondo!
I can't see the pictures from here (corporate firewall) but I suspect a bit of plastic autobody filler would fill the hole, could be sanded smooth, then a spot of paint would blend it right in ...

mini
11-25-2008, 10:21 AM
cheers--
mikey

Hi,

I've got a pair too. Mine too show some unexpected - as to say - sloppy machining. But it doesn't hurt! There was absolutely - measured against my measurement skills - no difference between a concise fitting of part I and II and coarse mounting. Holes might cause high frequency loss, but it would be less than half of a dB, so my expectation.

If the plate is still connected to the bell firmly I would not waste a thought on that issue.

Congratulations!

ps: I wonder how You will hear recorded music without mentioning the speakers all the time! "... virtually the speakers vanished and left just music and me ..." Ha ha ... - welcome to the club :applaud:

demon
11-25-2008, 12:21 PM
Please post some more pictures from a greater distance that shows this area more in context. And maybe you could also post some pictures of what the good one is supposed to look like.

John

good point!

so, lets close in on the other one:
http://i303.photobucket.com/albums/nn153/mikeysound/P1080337w.jpg
http://i303.photobucket.com/albums/nn153/mikeysound/P1080354w.jpg
http://i303.photobucket.com/albums/nn153/mikeysound/P1080348w.jpg
http://i303.photobucket.com/albums/nn153/mikeysound/P1080352w.jpg

the warp seen in the pictures in the first posting is very solid and brittle, it cant be flatened without beeing destroyed. i think this is the layer wich was soft when put into the form of the horn, before the fiberglass. it must have been hardened out that warped way during production.

so maybe i should sand down the warps until they are even, fill the holes and dont care anymore about it.
on the other hand, i could also start not caring right now, as mini kinda suggested. without all the work!

no, if there is some experience with this issue already, id like to know about the possibilities.

anyway i will try them soon. wich leads me to this question:
wich type of screws should i get to connect the throat to the bell? if possible i want metric. im not into screws, so before i run to the shop i need some proper numbers, not? mini helps again?
:applaud:

thanks a lot,
cheers--
mikey


ps:

"... virtually the speakers vanished and left just music and me ..." im not beeing ungrateful here, but if there is a chance to let the horns vanish, id take it. i mean, they are huuuuuuuuge butts :D


Ha ha ... - welcome to the club
thanks!

1audiohack
11-25-2008, 06:07 PM
The black stuff is gel-coat, a polyester resin with powder as filler and color. It is hard and brittle as you describe.

Gel-coat is sprayed into, or onto the mold and the fiberglass resin matrix on top and rolled or vacuumed into place. Gel-coat does not by itself adhere well to many surfaces so if the glass/resin does not come and stay in contact with it before it cures, it can peel like old paint.

It has delaminated from the fiberglass either from stress, or insufficient bonding.

You can see the machine marks on the edge where it was trimmed flat before it was mated to the flange.

I would at least grind it off where it protrudes into the path. Be careful, it can be quite sharp.

My 2360's came with 1/4" by 1.5" bolts, in metric as close as you would find in the US would be 40 by 6 mm.

Use a nylon lock nut or some kind of prevailing torque nut as the parent material of the horn is to soft to load the threads of a standard finish nut sufficiently to keep them tight.

Enjoy them, I love mine!
Barry.

demon
11-26-2008, 12:07 PM
today i screwed the horns.

:)

what?
screwed them together, of course! as far as i can hear, there is no problem audible, no problem at all, no, everything but problems.
they simply sound AAAWWWSOME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:applaud:

whoooooheeee!!!

anyway, i will come back to this thread soon, so dont go way or flip the channel. or better yet, flip the channel, but flip it to my documentational thread:
http://www.audioheritage.org/vbulletin/showthread.php?p=229473#post229473

cheers, lotsa cheers,
mikey