Author Topic: Inexpensive speaker repair suggestion.  (Read 149 times)

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Offline RacerX

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Inexpensive speaker repair suggestion.
« on: May 21, 2018, 07:54:33 pm »
Hello,  I have a Sunn Beta 402 that I have let set for a long time. I went to use it and noticed all four speakers have identical cracks. Only one crack per speaker, and all are the same. I was pressing on the cone to get the separation seen in the picture. The material actually closes up tight without any pressure on it. I need inexpensive repair so someone can use it long enough to try my amp or I can make a short video to demastrate it. I understand it would be best to replace or recone them but it looks like the value of a Beta 402 would only be worth what it would cost to properly repair it, or even less with shipping’s . I was thinking of using some fingernail polish or latex caulking?  I also read in a post where a guy said to lightly spray the cones with lacquer to refresh them. So I was wondering if maybe there is a material like felt, I could embed in the crack and use some lacquer as an adhesive. Any advice would be appreciated. Thank you in advance.

Offline RacerX

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Re: Inexpensive speaker repair suggestion.
« Reply #1 on: May 21, 2018, 07:58:17 pm »
Sorry, pictures from iPhone load as incompatible.

Offline eddiemac

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Re: Inexpensive speaker repair suggestion.
« Reply #2 on: May 22, 2018, 06:54:41 am »
I would try a light application of epoxy glue, to the crack only  - just enough so it stays solidly together.

Offline bigobassman

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Re: Inexpensive speaker repair suggestion.
« Reply #3 on: May 22, 2018, 06:31:30 pm »
I've repaired several splits like you have.  You need a sheet of paper towel and some flexible rubber glue/cement that is applied with a brush.  Cut a strip of paper towel a little larger than the tear.  Apply a layer of glue around the tear and then lay the paper towel section as smooth as possible over it.  Then put a layer of glue over the top of the towel extending out on the cone some.  If possible, do the back side as well.  Works great!   :-)
"You can't have too much bass."

Offline GrannyGremlin

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Re: Inexpensive speaker repair suggestion.
« Reply #4 on: May 23, 2018, 12:03:25 pm »
Nice clean tear - easy to fix.

Don't use epoxy - too heavy.  Rubber/contact cement only if it's a poly cone vs paper.  For a paper cone like this one use regular white/school glue.  Water it down a bit so it doesn't go on thicker than necessary, dries slower, and paints on with a brush easier (though sometimes I just finger it on).  Alternatives include Wood Glue and  Modge Podge (in both cases def water down) - both being water based as well and very similar.

Paper towel is a bit thick - I use toilet paper (if thick/multiply, use a single ply).  Layer of glue on both front and back, line up the tear, stick on TP patch on rear only ( don't want to see that from the front), and then paint over the patch with another layer of glue (watering it down as mentioned also helps is not rip the TP when you top coat). Optionally another coat on the front as well if you're worried it's not strong enough.  Be conservative with the glue - you can always add another coat later.

Basically you don't want to add significant weight in an unbalanced way. That can be bad.  Adding weight in a balanced way (e.g. paint the entire cone with watered down glue/mod podge) is a common mod in DIY HiFi circles for cheap drive units when you want to lower the resonance/bass response and don't mind risking the loss of a bit of high end (cuz there's a tweeter for that anyway).  I've repaired many a low power vintage alnico this way (reconing is not worth it - costs more than replacing the speaker).  After a few you even learn to make them not so damn ugly.