speaker cone patch

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speaker cone patch

Postby nyazzip » Sun Nov 23, 2008 12:22 am

a few days ago i was funning up a "speaker cab" using a giant cardboard box with a hole cut into it, just to hear how it would sound. to mount the 12" speaker(1950s alnico jensen 12", one of the low power models that everyone scorns) i used some bathtub caulking, as screws wouldn't work on thin cardboard. anyway, as i finished, i dropped the tube of caulk, and the tip of course fell into the speaker, poking a hole into it about an inch from the dustcap- real freaking nice!
after walking away from it for a few minutes and cooling off, i decided to try and repair it.
first i used various flat objects(popsicle stick worked best) to coax the jagged paper tears back to their original plane, from behind. the ancient cone paper is quite thin and very delicate, so i figured i would use a little graft of tissue paper(or whatever you call it- the uber lightweight stuff that gifts are sometimes wrapped in...craft paper?). i cut out a little oval, big enough to cover the hole and tears. for glue, i made a solution of white flour and water, about the consistency of elmers glue( i have used flour and water in the past to bond this same type of paper to make hot air balloons, with good results). then for good measure i added some actual elmers glue. using tweezers, i dipped my little patch into the glue solution, placed it over the hole, and carefully smoothed it out.
when it dried, i was amazed at how smooth the repair is....i can barely detect the seams with my fingertips. aside from now sporting a whitish oval, i suppose the speaker is probably very close to being sonically and structurally what it was before the incident; most importantly i suppose i have prevented the tears from spreading.
if i had to do it again, the only thing i would have done is maybe dab some glue around the "hole zone" with a Q-tip before i added the patch, just to make sure the cone paper was good and saturated.
this glue job might not hold up under high power woofer/guitar applications, but i would certainly give it a shot. i am pleased with my results. oh, and the giant cardboard speaker cab sounds...a bit flabby Yellow_Light_Colorz_PDT_16
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Postby mesherm » Sun Nov 23, 2008 6:13 pm

I trick I've usd before is to use two samarium magnets out of a dead computer hard drive. Place one each in a heavy plastic sandwich bag and appy glue and or a patch to the cone . Put one magnet on each side and wait a day. Pulling magnets off can be a bit tricky especially if close to the metal spider or magnet. But it will make a nice flat patch.
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Postby nyazzip » Mon Nov 24, 2008 6:45 am

magnets....that's a great idea!
except i'd probably go with something less potent. the magnets i salvaged off a hard drive are so strong they're almost dangerous...its all i can do to get them apart, and thats without a speaker in the way
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No lumpy gravy please

Postby EWBrown » Mon Nov 24, 2008 11:30 am

I've used the "paper patch" cone repair in the past, several times over the years. tissue/toilet paper is a bit too thin and flimsy, and writing paper is a tad too thick, something in between would be best, I used the paper that sometimes comes with new shirts, or as "wrapping" inside some boxed gift items. I suppose that Japanese "rice paper" would be a good patch choice. Keep the amount of glue (I also used Elmers, usually watered down a bit to make it thinner and flow easier) to a minimum effective amount. Flour and warer will work, just make it nice and smooth, with no lumps Yellow_Light_Colorz_PDT_02

The last step, I used black magic marker to darken the patch against the dark cone, and from a distance it was nearly invisible.

If the tear or rip is especially long, I'll apply a patch on the back side of teh cone as well, if it is eradily accessible.

This works for small tears, or poked holes (it's amazing what a rugrat armed with a sharp pencil can do)... :o Yellow_Light_Colorz_PDT_11

This works best on the cone itself, and only in an emergency on a paper suspension, with thin tissue (or toilet paper).

/ed B
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Postby Quad » Mon Nov 24, 2008 9:55 pm

Adding a dash of copper sulphate while preparing the flour glue makes
it unpalatable to rats or insects.
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Postby nyazzip » Tue Dec 02, 2008 12:20 am

i don't have much of a rat problem, but i have to take back my criticism of my cardboard box speaker cab: it sounds fantastic with a 5w guitar amp!! better than any "real" cab i've plugged it into. in fact, i was just looking at those pink foam panels they use to insulate houses with...it is really rigid and stiff- perfect for model airplanes, and.... home recording speaker boxes?
i think i'm going to make me a monster 1x12 cabinet out of it....
it will be disposable, the size of a closet, resonate at 3Hz, weigh 5 lbs, and it will cost me 10 bucks! i just need to figure out how to join the corners.
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Postby EWBrown » Tue Dec 02, 2008 6:12 am

You could join the corners with any decent glue - even "white glue" should work. Make some joiner blocks out of 1 inch cut strips of the same pink insulating foam and it will make it more durable and lless prone to being shaken apart bu those thunderous low notes Yellow_Light_Colorz_PDT_04 Yellow_Light_Colorz_PDT_06

I was thinking of making some multi driver "towers" out of PVC fence post and a bunch of cheap "full range" drivers from Parts express, and maye badd in some of thir cheap neodymium tweeters if needed.

That's a "next year project"....

/ed B
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Postby Spraiski » Tue Dec 02, 2008 11:36 am

It would be pretty simple to make a couple of test pieces with whatever glue you have on hand.

Glue them together, make sure the glue is well cured...and then break them :P
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Postby Ty_Bower » Tue Dec 02, 2008 11:53 am

I betcha this stuff would stick to that pink foam packing board real good:

http://www.eclecticproducts.com/shoegoo.htm
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Postby EWBrown » Thu Dec 04, 2008 6:52 am

Gorilla Glue would work, too, as it expands to fill in the voids. Good stuff, but it can be messy stuff to work with... :o

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