Cause of speaker surround separating from driver |
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itskabini
Registered User Joined: 03 April 2019 Location: London Status: Offline Points: 49 |
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Posted: 04 August 2021 at 1:45pm |
When I bought my sound system a lot of the subwoofers had blown drivers, although the damage seemed a bit different to what I've seen before. The surround seemed to be tearing away from the cone itself at various points around the edge. The speakers seemed to still work OK however, voice coils were fully functional although they didn't sound quite right, and on removal they seemed a lot darker than a fresh one.
I initially thought this was likely due to overexcursion causing damage, although looking at a winISD prediction, the maximum excursion should have only been about 17mm to a xlim of 22mm. The signal getting to the drivers was likely heavily compressed however due to the processing that was used with the system before, so this could have caused problems. I've also had someone suggest that this could be damage due to humidity, as the speakers were used in a nightclub that probably wasnt that well ventilated. What's people general opinion on the problem? I'm now running the system with some very conservative limiters, but if excursion wasn't the problem before then I can open them up a bit.
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1083 |
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Most likely over excursion, are you using a highpass filter?
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itskabini
Registered User Joined: 03 April 2019 Location: London Status: Offline Points: 49 |
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The system was set up with a highpass filter at 25hz before, I'm running this a bit higher now to be safe.
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Tinnitus Rex
Registered User Joined: 31 October 2020 Status: Offline Points: 287 |
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The edge suspension can rot and become brittle after time. The edge support,spider and leadoffs are the only mechanical parts of the cone and have to survive trillions of movements .The highest stress point is where the cone meets the fabric edge support (as your photo demonstrates) there are four places where the weave of the fabric joining the cone cross at a + rather than an X. The + parts are weaker due to having only one thread direction taking all the stress. If a small air hole occurs in the fabric edge the box pressure soon blasts a bigger one. it is difficult but not impossible to fix using contact adhesive and fabric patches or replace the edge (pita) The edge support and the spider have to provide the spring force that brings the voice coil back to its zero reference point ,these can stretch and lose their spring over time. The "tinsell" leadoffs often need replacing in time ,All these factors decide is it worth fixing or reconing.
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"couldn't we just like... use headphones?"
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itskabini
Registered User Joined: 03 April 2019 Location: London Status: Offline Points: 49 |
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I guess this could have just been normal wear and tear then. They would have been getting used hard multiple times a week for years.
I've already reconed all the ones with visible tearing, was just trying to ensure it doesn't happen again
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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"and on removal they seemed a lot darker than a fresh one." That's most probably due to HEAT! The obsession with trying to squeeze every "Watt" from the speaker - and actually loosing dB's - and lifetime due to overheating the things. |
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Earplugs Are For Wimps!
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APC321
Young Croc Joined: 24 August 2013 Location: West Midlands Status: Offline Points: 684 |
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+1 |
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4D
Old Croc Joined: 13 November 2008 Location: Winchester Status: Offline Points: 4257 |
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cone damage from mechanical wear & tear & old age whilst a heavily compressed signal being not far off straight DC is quite likely to nicely toast voice coils
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DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"
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