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Thread: KEF B139 expert needed

  1. #1
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 447
    I'm Chris.

    Default KEF B139 expert needed

    I have extracted a pair of KEF B139 drivers from some unloved vintage Radford cabinets. They look as if they have been in there for 40 odd years, but they are different, in that one has a rubber cone surround and one has an impregnated cloth surround. I will post pictures when I can, but I have two questions initially.

    1. Was the KEF B139 ever made with impregnated cloth surround or is this likely to have been a very early repair?

    2. I have read somewhere that Radford commissioned their own lightweight cone B139s. Is this true?

    Thanks

  2. #2
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 447
    I'm Chris.

    Default

    OK, can finally add some pictures

    Rubber surround vs impregnated cloth surround, and an overall view
    Attached Images Attached Images

  3. #3
    Join Date: Feb 2008

    Location: Middlesex, UK

    Posts: 2,993
    I'm Alex.

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    All the B139s I've been though, and that's about 12, have have the rubber surround, but I believe that earlier ones have had cloth like one of yours, and I have seen pics of rotted early surrounds that might have been foam, though I'm not sure of this.

    I read somewhere that Radford used a lighter cone on their two unit systems. I repeated it somewhere, can't remember where! And I don't remember where I got the original info!

    It might be possible that both your units are original, if they were made at the changeover time for the surround type.
    Spendorman

  4. #4
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 447
    I'm Chris.

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    Quote Originally Posted by spendorman View Post
    All the B139s I've been though, and that's about 12, have have the rubber surround, but I believe that earlier ones have had cloth like one of yours, and I have seen pics of rotted early surrounds that might have been foam, though I'm not sure of this.

    I read somewhere that Radford used a lighter cone on their two unit systems. I repeated it somewhere, can't remember where! And I don't remember where I got the original info!

    It might be possible that both your units are original, if they were made at the changeover time for the surround type.
    They certainly have the same aged appearance. Funnily enough vintage stereo Saba radios and radiograms often had slightly dissimilar driver construction, I think to exaggerate the stereo effect in the early days of stereo.
    Last edited by bumpy; 05-10-2017 at 19:02.

  5. #5
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 28,517
    I'm Geoff.

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    Not seen the fabric surround version before. No doubt it's early. There was also a version with clear/white foam surrounds, with the 'roll' convex, as opposed to the more usual concave.
    Mr. Tact!

    Main system: MMs/ADCs/Low output MC's/One rare Japanese SUT/One scarce British phono stage/various tonearms/hefty Japanese DD TT and hefty Japanese BD TT and small British BD TT. 4 CD players/2 jitter buster/2 DACs/Valve buffer. TVC stepped attenuator or valve pre-amp or solid state pre-amp. Current dumping power-amp or either of two Class A SS power-amp or Class A EL34 valve monos or big Japanese (part Class A) integrated. Big dual concentric speakers/Smaller dual concentric speakers/Two way British compacts and full range speakers, amongst others. And too much more to list!

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