Coral Beta rubbing voice coil / cloth surrounds - diyAudio
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Old 8th April 2008, 09:28 AM   #1
RemcoB is offline RemcoB  Netherlands
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Unhappy Coral Beta rubbing voice coil / cloth surrounds

When further listening to my newly arrived and otherwise good sounding Coral Beta 10Bs, I noticed a buzzing sound on certain bass notes (mainly lower cello and middle electric bass). When I unplugged the buzzing driver and gently pushed the cone inwards, I heard a rubbing sound. Very scary. Only if I pushed it to one side however. I suspect that either the voice coil is damaged, or I need to re-align it. Maybe both. Anyhow, I need to somehow remove/release the cloth surrounds and spider. Anyone done this before? What type of glue can I use to stick the surround to the frame again, if I manage to salvage it? Also, is there a place where I can buy new white cloth surrounds for a 10" speaker?
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Old 21st April 2008, 09:43 AM   #2
crick is offline crick  United States
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What I have done in the past with antique radio speakers is to first remove the dust cover.Then I take cut up pieces of film negitive roughly 1/8 wide and slide them down in roughly 1/8 appart all the way around.Then I take a water mister bottle and LIGHTLY dampen the cone to relax the paper fibres.Give it a couple days to dry depending on humidity.Slide the film back out and do the push test.Iv'e had good luck with this so far.
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Old 21st April 2008, 01:48 PM   #3
Bluto is offline Bluto  United States
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Old 21st April 2008, 04:35 PM   #4
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Crick, that's sounds like a great idea. Thanks for that.
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Let's help Ruth and Dave
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Old 21st April 2008, 05:51 PM   #5
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Coarl Betas have phase plugs and no dustcaps IIRC... you most likely have a bit of crud in the gap... 1st try i'd place the speaker face down and just play it for awhile. If that doesn't work, get into the gap* with something thin (ie like a strip of business card) and see if you can work something loose. If that doesn't work then you can start panicking. I've never had one of these (or the 8) in my hands so i don't know if they are realignable with major surgery, and if you have an "expanded"voice coil repair requires dissassembly and rewind the oice coail (in which case it will likely never be the same as the other)

*(i don't know this for a fact, but i suspect from some of the inquiries i have had, that the phase plugs can be unscrewed)

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Old 21st April 2008, 08:44 PM   #6
RemcoB is offline RemcoB  Netherlands
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Thank you for your reactions. I sent my corals away to a speaker repair guy, who did something with the spiders to realign them. It seems to work properly. If the problems reoccur, I'll try to realign them with water mister bottle & film negative.


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Old 21st April 2008, 09:29 PM   #7
crick is offline crick  United States
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Good luck and let me know if you have any questions.

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Old 9th June 2017, 05:12 PM   #8
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The phase plugs are removable. I just used my finger and thumb and was able to remove both.
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