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Thread: Radford System

  1. #11
    Join Date: Sep 2014

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    I'm John.

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    Have a look at this Barry, solid state rectification for IMA series but Iím pretty sure these are K25 amps. You can just see the XLR input in the EBay photographs. It seems the K25 were a modified MA-25 for the BBC specifically for use with the KEF LS5/1A monitors. They amps have a filter for evening out the speakerís frequency response but this can be switched out. They also have input trim pots but no impedance selector switch.




  2. #12
    Join Date: Sep 2014

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    I'm John.


  3. #13
    Join Date: Jan 2009

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    I'm openingabottleofwine.

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    Oh - this is embarrassing!

    The table you show is exactly the same as the one shown in our article, there is thus no excuse for me not knowing about it. So definitely a K25, which if the frequency equalisation can be switched out, makes them very desirable items.

    I admire your diligence in tracking down the identity of the Radford amp. Well done!
    Last edited by Barry; 19-04-2021 at 11:51.
    Barry

  4. #14
    Join Date: Sep 2014

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    I'm John.

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    I’m sure there’s been some water under the bridge since the article was written Barry

  5. #15
    Join Date: Feb 2013

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    I'm Grant.

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    Quote Originally Posted by barry View Post
    oh - this is embarrassing!

    the table you show is exactly the same as the one shown in our article, there is thus no excuse for me not knowing about it. So definitely a k25, which if the frequency equalisation can be switched out, makes them very desirable items.

    I admire your diligence in tracking down the identity of the radford amp. Well done!
    was a long time ago so i wouldnt worry.. I often forget stuff same day i did it lol
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  6. #16
    Join Date: Jan 2009

    Location: Essex

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    Thanks Guys, however I do pride myself in having an encyclopeadic knowledge about certain audio brands. Anyway, there was no excuse for me not having carefully read the article I co-wrote.

    Returning to the eBay sale, £2,500 would IMO seem to be a bit of a bargain for the Radford system.
    Barry

  7. #17
    Join Date: Sep 2014

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    I'm John.

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    Barry, it gets worse , have a look at post #16

    https://theartofsound.net/forum/show...s-1960-s/page2

    Looks like the amplifier output impedance is 25 ohm but maybe itís a multi tap transformer.

  8. #18
    Join Date: Jan 2009

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    The BBC had a habit of taking comercially manufactured items and custom modifying them (or having the manufacturer do it) for their purposes. They did this with Leak, Quad and Radford amplifiers, and with turntables by Garrard, Technics and EMT.

    All of these items were given BBC designations; AM_/_ for amplifiers, and RP_/_ for turntables.

    Ferrograph were another British company who would supply many specialised/customised versions of their reel-to-reel recorders. These would have been variously for the BBC, the Admiralty, and the secret services and GCHQ.
    Barry

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