7c crossover issues? Sticky varnish?

npatt
npatt Posts: 3
in Vintage Speakers
Hi folks,

Nice community you've got here :)

So I recently received a pair of 7c from a neighbour...

One speaker sounds great, but the other isn't outputting anything from the woofer.

I'm thinking it's an issue with the xover as the driver itself does pass audio when the xover is bypassed?

Any common issues I should check first?

Also, any advice on reconditioning sticky varnish? Cabinets are in otherwise good condition, just a bit tacky to the touch.

Drivers have 1985 dates on them, btw

Thanks in advance!
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Comments

  • Astrl55
    Astrl55 Posts: 64
    I imagine most here would give you the same advice -- rebuild your crossovers.
    They're nearly 40 years old.

    The varnish will probably need to be stripped.
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  • boston1450
    boston1450 Posts: 7,658
    edited January 28
    I would take good woofer out & put it in the other cabinet & see if it FOLLOWS.. WHILE your in there look at the crossovers to see if you can see anything out of the ordinary. Check bad woofer to see if Magnet has shifted. The glue holding magnet over time degrades & shifts with the slightest bump. REUSE the woofer gaskets if it isnt rip'd... Don't worry about sticky woofer. That's normal. Use 100% real Windex to clean them. Be easy with micro soft cloth..You may want to Reglue your magnets on woofers at some point to help prevent shifting magnets & the crossovers are OverDue for a crossover refresh. EDIT : Welcome to the forum
    ..
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  • Astrl55
    Astrl55 Posts: 64
    boston1450 wrote: »
    ... Don't worry about sticky woofer. That's normal. Use 100% real Windex to clean them. Be easy with micro soft cloth..

    Pretty sure the OP's reference to stickiness has to do with the cabinet, not the woofer.
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  • F1nut
    F1nut Posts: 50,654
    The material on your cabinets is likely vinyl, so no varnish. Try scrubbing them down with original Windex.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • npatt
    npatt Posts: 3
    Thanks all for the great suggestions and advice, much obliged!

    Will have a go during the week and report back.
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  • npatt
    npatt Posts: 3
    UPDATE:

    Gave the problem driver a (gentle) poke and, sure enough, it looks to be stuck.

    Tried the known good driver in the problem cab and hey-presto, all sounding pretty dang good!

    So both xovers seem to be working & just the one bad/stuck driver.

    What's the current advice on re-gluing magnets/servicing drivers?

    Meter shows 3.7 ohms for good driver and 3.9 for bad

    A gentle application of original Windex worked a treat on the veneer too - great tip! :)
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  • joebass3
    joebass3 Posts: 286
    Everything you need to know about repairing your driver... https://forum.polkaudio.com/discussion/197152/diagnosing-fixing-shifted-polk-mw-drivers/p1
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  • F1nut
    F1nut Posts: 50,654
    edited March 14
    Meter shows 3.7 ohms for good driver and 3.9 for bad
    The difference between those two is insignificant.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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