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Thread: Capacitor replacement ??

  1. #1
    Join Date: May 2016

    Location: Milton Keynes

    Posts: 519
    I'm Andrew.

    Default Capacitor replacement ??

    Is it a given that vintage speakers must have their capacitors replaced in order that the speaker performs as it should ?
    If the circuit board is free of leakage and the speakers still sound great to your ears why bother or how would you know for sure that they've degraded?

  2. #2
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,235
    I'm Jez.

    Default

    "Circuit board leakage" is rare at the best of times and a complete non issue in a crossover.

    It is not a given that caps should be replaced no. Non electrolytic caps don't wear out.... Some speakers don't use electrolytics but most have at least some.

    If the speaker sounds fine to you then that's the main thing. Many speakers have been ruined by enthusiastic amateurs messing with them (as have many amps etc!).

    It needs to be understood that good speaker designers will have taken account of the shortcomings of the cheaper parts used in the crossovers of often even expensive speakers. Electrolytics have very wide tolerance margins, +/- 20% is good for electrolytics! They also have quite high ESR (equivalent series resistance), as do more affordable inductors in most speakers. Replacing either with ostensibly much better quality components can have a very bad effect on the flatness of the frequency response of the speaker.

    Overall the only components likely to wear are electrolytics. To test these you need to be able to measure the capacitance, and the ESR. ESR meters are rather less readily available than a multimeter with a capacitance range but can be obtained these days. Measuring just the capacitance is usually pretty useless...

    Now when you do measure the capacitance and find that 22uF cap reads 17uF do you assume it's faulty? That's actually within spec for one thing and for another, how certain are you that the manufacturer was not selecting ones around this value deliberately? Some do. Such as KEF in all their Reference series speakers. Some will not be too picky and are happy to just fit 22uF caps knowing fine well they could be 20% higher or lower than that.

    To get to the point, I advise leaving everything alone except, in the case of very old speakers, electrolytic capacitors and then they should be replaced by a very similar equivalent part, not one of vastly greater quality.

    If you are planning on using polyprop caps from the likes of Mundorf etc and flat tape wound air cored inductors then you should know what you are doing to a degree where you certainly would not need to ask the likes of me about it! In effect, you would need to be capable of redesigning the crossover to allow for the superior characteristics of these components.
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  3. #3
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 3,501
    I'm Alan.

    Default

    Excellent advice Jez

  4. #4
    Join Date: Dec 2015

    Location: vancouver

    Posts: 642
    I'm danilo.

    Default

    All Good points well said.
    However Vintage suggests Old and as such were quite possibly 'voiced' for sources / amplifiers that were a bit short on frequency delivery.. by current standards.
    Meaning they can be somewhat dull/lifeless.. Today.
    NO big deal to swap out the electros, even the film caps for fresh ones or even upgrade the coils (keep track of the oem Coils' ESR you might needs add a resistor).
    Important to do this neatly sans damage and SAVE all the removed bits for when/if you decide to try the experiment in reverse.
    This IS a hobby.. have some fun and learn something in process.
    My audio bits: Thorens / diy phono, CD/dvd player(s), diy pre, F6, Tannoy Golds in my boxes / my xovers, and of course all strung together with basic diy Wires
    Lots of Cd's, yet more audio files, a couple of hundred semi worn Lps.

  5. #5
    Join Date: May 2016

    Location: Milton Keynes

    Posts: 519
    I'm Andrew.

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    Thank you very much for sharing your knowledge. I'm happy to leave well alone.
    Cheers

  6. #6
    Join Date: Dec 2015

    Location: vancouver

    Posts: 642
    I'm danilo.

    Default

    Not a lot of sense of adventure in that .. is there?.
    You may have been completely correct in your initial Assumptions...re sound age related degradations.
    I first replaced the electros on My Tannoys on their 10th B'day. Despite trepidations at the time, the result was instantly amazing.
    Consequently over the ensuing decades not much at all remains of the original Crossovers.
    Yesss there have been more than few backwards steps.
    But again it IS a hobby. Live and learn.
    Want easy non involvement? Only shop at a Dealers' and/ or buy Bose Or Beo .
    My audio bits: Thorens / diy phono, CD/dvd player(s), diy pre, F6, Tannoy Golds in my boxes / my xovers, and of course all strung together with basic diy Wires
    Lots of Cd's, yet more audio files, a couple of hundred semi worn Lps.

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