Here's a picture example of why I don't trust the longevity of Poly speakers...

Discussion in 'Speakers' started by Harvestor, Feb 13, 2019 at 11:15 PM.

  1. Harvestor

    Harvestor Super Member

    51661740_10161299833260277_3114362193139728384_n.jpg
    51956045_10161299833325277_6560247603278118912_n.jpg
    As you can see the cracks are starting to form near the voice coil. .
    I trust Good Old Paper pulp and treated paper pulp because there are speakers still in existence over 70 years of age made with paper..
    Infinities polydome is another example of failure with Poly..

    What are your thoughts?.. fellow members
     
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  2. RxDx

    RxDx Speaker collector Subscriber

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    Do we know the history of those systems? I can see a few hundred watts causing
    a little damage. Reminds me of the HPM graphite woofers...
     
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  3. man00

    man00 New Member

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    Looks like results from Rap music :)
     
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  4. jazzmans

    jazzmans Super Member

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    I don't disagree with this opinion. There are many different formulations of 'poly' however. My RS2b use poly cone woofers with the phase plug bullets, They are 40 years old and still pliable and strong with no evidence of any form of oxidation.

    My Kappas all were in need of severe maintenance, as regards the polydomes. Either the thickness, or the formulation was no bueno long term.
    The IMG cones are nearly indestructable, afaik. I'v never never damaged one, anyway, and I've had IMG cone drivers since 1993.
     
  5. xero-D-hero

    xero-D-hero Super Member

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    This ^^^^ x2...

    Cuz honestly it looks to me like those were "punched in" vs. being "busted up" by normal usage.
    It may be that with those flat poly dustcaps the cone took all the damage instead of the dustcaps themselves.

    FWIW

    Bret P.
     
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  6. ETLS

    ETLS metacarpophalangealcranium Subscriber

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    Norman Labs. Opaque white poly woofs, still working. No problemo
     
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  7. ic-racer

    ic-racer Super Member

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    Paper would probably be in shreds with the same trauma.
     
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  8. SaturationPt

    SaturationPt Fickle Collector Subscriber

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    Or could have softened from being flexed, whether a crease is visible or just internal. Cones of all materials whether titanium, carbon-fiber, graphite-filled poly, mineral-filled poly, ceramic, pulp, pulp/aquaplas, ... all have their yield point beyond which they will have irreversible damage.

    I hate to stereotype here, but the only CV! speakers I own are a permanent part of my test bench. It has been my experience (in days gone by) that most CV! buyers buy them as party speakers, and they get abused.
     
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  9. bbqjoe

    bbqjoe Void where Prohibited Subscriber

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    Are these in the back window of a car in Arizona?
     
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  10. Harvestor

    Harvestor Super Member

  11. WE6C

    WE6C Well-Known Member

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    Rap is music?
     
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  12. goodolpg

    goodolpg Just an old fart trying to help.

    I have a couple dozen Infinity poly coned drivers, all 35 years old roughly.
    No signs of the actual poly cone degrading.
     
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  13. musichal

    musichal poet emeritus Subscriber

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    I've owned many speakers with poly cones and found them quite rugged.

    My current speakers employ aluminum cones, or titanium domes, or ceramic-coated aluminum/magnesium alloy cones and domes. As someone posted above, any material can be damaged by abuse.
     
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  14. slimecity

    slimecity Super Member

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    Yea - I agree with others that there must be tons of different formulations of poly cones.

    All the older KEFs I have seen have been fine - including mine.

    I think a lot can be said about rigidity of the cone - or lack of - I think the latter could lead to less stress on the cone, and eventually, damage like the type you have shown.

    Plus, isnt the (informal) motto of Cerwin Vega "SLAM IT HARRRRRRD BRUR!!!!!!" - Im not sure, I could be making that part up.....
     
    Last edited: Feb 14, 2019 at 7:27 PM
  15. Ross6860

    Ross6860 AK Subscriber Subscriber

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    Ten Infinity woofers, ten midranges, and a pair of KEF 104/2 and they are all fine.

    Add a pair of IMG that were accidentally torture tested last night. BTW, don't hook up your CD player to the second pair of outputs on your preamp:eek:

    Although I also have paper-cone/cloth surround speakers that are 63 years old and doing fine.
     
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  16. Ohighway

    Ohighway Wannabe Minimalist Subscriber

    Well I have plenty of speakers with poly cones that seem to be getting along just fine.

    That being said, I did run into a problem with a set of midrange drivers ( Elac 4/200 from IMF Supercompact II) that I discovered when doing a refoam. At first it appeared that the edge of the poly cone was brittle, but as I inspected further I found the poly cone was cracked near the voice coil. Seems the entire poly cone got brittle over time.

    I see some have suggested yours having been overdriven or hundreds of watts poured into them. Maybe , maybe not, but certainly my midrange drivers did not have the problem of high wattages hitting them or massive amounts of excursion causing the cracking.
     
    Last edited: Feb 14, 2019 at 5:01 PM
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  17. Tom Brennan

    Tom Brennan AK Member

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    Yeah, it is. You know, it’s been around now, what, 25-30 years? Time to accept it or at least stop bitching about it.
     
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  18. Harvestor

    Harvestor Super Member

    They are not mine, I came across this on market place
     
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  19. Ohighway

    Ohighway Wannabe Minimalist Subscriber

    Why should someone accept something they obviously don't like? To please you?

    Perhaps you should accept that some people don't like rap , and are entitled to their opinions about it. Just sayin'....
     
  20. Harvestor

    Harvestor Super Member

    True
     

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