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Thread: Tweeter decreased frequency . Csuses?

  1. #1
    Join Date: Aug 2012

    Location: Lincs

    Posts: 928
    I'm Philip.

    Default Tweeter decreased frequency . Csuses?

    Hi,

    I have a 30 year old tweeter that has an obviously reduced frequency range.

    Listening to one tweeter and then the other, one does not play as high when i use test tones.

    They are kef t33 ferrofluid filled.

    Is it possible one is gunned up more than the other with congealed old ferrofluid?

    Other than crossover or amp which i will test by swapping tweeters, etc, what could cause a decreased frequency response?

    Also, what physically breaks when a tweet fails?
    Is it the voice coil breaking?

    Thanks.

  2. #2
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 44,307
    I'm Geoff.

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    Dried ferrofluid is likely, but shorted coil windings are also possible. Check the coil resistance with a meter.

    Failing crossover caps could also be the cause.
    "when common sense, logic and plausibility are excluded. All that remain are foolishness and lies"

  3. #3
    Join Date: Jan 2009

    Location: Deleted

    Posts: 6,674
    I'm Deleted.

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    If electrolytic capacitors are used in the crossover (which they would have been thirty years ago) then they can increase in resistance as they get older. Also, if there is ferrofluid in the voice coil gap it could have dried up.

    óó
    Edit, Yes, itís the voicecoil breaking if anything, there isnít much else to break.
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  4. #4
    Join Date: Aug 2012

    Location: Lincs

    Posts: 928
    I'm Philip.

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    So, swapped tweeters over and the problem follows the tweeter.
    So problem is with the tweeter.

    I have cleaned the gap and the coil on the bad tweeter.

    My hearing is pretty crap.

    The good tweeter i can hear the 7 khz test tone.
    The bad tweeter i can only hear the 4 khz test tone.

    Here are some images,
    Any obvious problems?

    Thanks





  5. #5
    Join Date: Mar 2017

    Location: Seaford UK

    Posts: 1,528
    I'm Dennis.

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    You should consider that the surround may have changed its compliance.

  6. #6
    Join Date: Jan 2009

    Location: Deleted

    Posts: 6,674
    I'm Deleted.

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    Yes, was just what I was thinking.
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  7. #7
    Join Date: Aug 2012

    Location: Lincs

    Posts: 928
    I'm Philip.

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    What do you mean by surround?
    The diathram?
    Quote Originally Posted by Pharos View Post
    You should consider that the surround may have changed its compliance.

  8. #8
    Join Date: Jan 2009

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    No, the bit around the edge of the diaphragm that connects it to the rest of the component.
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  9. #9
    Join Date: Aug 2012

    Location: Lincs

    Posts: 928
    I'm Philip.

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    Quote Originally Posted by YNWaN View Post
    No, the bit around the edge of the diaphragm that connects it to the rest of the component.
    Ah...i see.
    So, nothing can be done then i guess.

    Not to worry, i knew it was buggered before purchase.

    Thanks.

  10. #10
    Join Date: Jan 2009

    Location: Deleted

    Posts: 6,674
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    No, if exposure to sunlight, smoke etc. has caused the suspension to harden then its stuffed.
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