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 Post subject: Speaker Repair
PostPosted: Dec Mon 04, 2017 5:06 pm 
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I repaired a tear in a speaker, while doing this I thought about how better it would look if I could paint the cone with black paint.
I bought a bottle of black nail polish. Does this sound like a good idea? any help would be highly appreciated.

Thank you, Jim.


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 Post subject: Re: Speaker Repair
PostPosted: Dec Mon 04, 2017 5:12 pm 
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Probably the main concern is that painting the cone will tend to stiffen it. Stiffening the main part of the cone is probably OK (may create a funny resonance in the mid range, but probably not a big issue). The bigger issue is stiffening the accordian edge (the "surround") which is designed to be compliant. If that becomes stiffer, there will be a significant loss of bass response. I usually only use very flexible adhesive (I use silicone caulk) for tears in the surround. You might mask off the surround if you're going to paint the cone.

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 Post subject: Re: Speaker Repair
PostPosted: Dec Mon 04, 2017 8:40 pm 
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No, if speaker cones were meant to be stiff and shiny like fingernails, they'd be made out of metal.

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 Post subject: Re: Speaker Repair
PostPosted: Dec Mon 04, 2017 9:00 pm 
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At one time speaker cones were made of metal.

Speaker cones need to have "stiffness" to them. You should be OK with painting the cone but don't paint the rolled edge (surround) as that needs to be flexible as pointed out above.

Dave


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 Post subject: Re: Speaker Repair
PostPosted: Dec Mon 04, 2017 11:09 pm 
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As may already be clear from the various comments above, the ideal speaker is infinitely stiff (but also lightweight) in the main cone area, and flexible with a well-defined fairly soft spring constant in the surround and spider.

You do in fact see various types of carbon fiber reinforced cones, plastic cones with fiberglass reinforcement, and even some aluminum cones out there in "high tech" speakers. Paper, when formed into a cone shape, is also really quite stiff, while being cheap and easy to make, so that's why most speakers have had paper cones for the last 90 years.

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 Post subject: Re: Speaker Repair
PostPosted: Dec Tue 05, 2017 3:54 am 
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no, it is a bad idea.

I did it once for giggles on an old useless 4 inch speaker.

it will become even more brittle and tight than it may be now.

steve

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 Post subject: Re: Speaker Repair
PostPosted: Dec Fri 08, 2017 7:25 pm 
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Some speaker cones are made of metal but not the surround. Paper has the advantage of cost and weight.

Bruce Hagen


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 Post subject: Re: Speaker Repair
PostPosted: Dec Fri 08, 2017 7:49 pm 
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The speaker cone should be of uniform thickness/density/weight/flexibility. Any type of repair results in a slight in-balance already. Adding more material would make it worse. I think something like a "Sharpie" type of marker that would dye the repair material would work better. If it's not visible behind the speaker cloth, then leave it alone.

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 Post subject: Re: Speaker Repair
PostPosted: Dec Fri 08, 2017 9:30 pm 
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We don't normally see the speaker cone when listening to the set---and usually we see almost none of it from the back. Ergo, the color does not matter.

What DOES matter is mass and stiffness. At low frequencies it's the mass of the whole cone, and the stiffness of the surround---that sets the dominant resonance, which is normally in the 100s of Hertz. Make the cone heavier, and the resonant frequency goes down.

At higher frequencies, you have "distributed" resonances, where the local stiffness and mass are both important.

The actual difference caused by painting a cone is pretty hard to predict, but we do know that there will be a change. It will sound different, but I doubt if we can predict better or worse.

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 Post subject: Re: Speaker Repair
PostPosted: Dec Sun 10, 2017 12:34 am 
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Speakers are also made out of wood. I know, because my JVC speakers have sake-soaked wood cones. Sounds pretty darn good! May be a gimmick but at least I have something unusual... 8)

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