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Vintage Tweeter ID

Discussion in 'classic' started by sybil, Jan 26, 2019.

  1. sybil

    sybil pfm Member

    Just picked up a trio of unidentified vintage tweeters on eBay for a fiver and I thought I would see if anyone here can ID them!

    https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/254082734107

    The ad says they are for a BBC LS5/9 but they look much older than 1983 and the LS5/9 always used an Audax 34mm soft dome to my knowledge? These look like a Melinex dome or similar and probably late 60s/early 70s vintage. It says 20mm on the handwritten labels but they look to be a bigger dome than an early T27, I can confirm when I receive them.

    Any pointers gladly received!
     
  2. Vinny

    Vinny pfm Member

    The soft dome tweeter was patented in 1967, so these are likely to be 1970's vintage at the earliest, which would fit with the description as being R&D examples. They certainly look like lab-made R&D parts to me (knowing naff-all about speaker development, but plenty about R&D builds in general).

    It is extremely difficult to tell from the photo's, but PETP (ICI trade name Melinex) and things like poly-propylene, do not age to a changed colour or milkiness. If they are milky and/or yellowed, you are really looking at a plasticised polymer, such as PVC.
     
  3. sybil

    sybil pfm Member

    Thanks Vinny this is good to know. I agree they do look like prototypes of something! Or perhaps they were designed for rear mounting where the faceplate wouldn’t be seen. I will put up some better photos when I receive them but I think the domes look clear and mostly unyellowed - the copper colour you can see is the edge of the voicecoil on the former. They are certainly distinctive looking, the Coles 4001 supertweeter had a similar look.
     
  4. Robert

    Robert Tapehead

    Look a bit like old Isophon units?
     
  5. JemHayward

    JemHayward pfm Member

    The diaphragm looks like a Coles 4001 - maybe with a custom faceplate?
     

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