Calrec CM654a Mystery

Discussion in 'Recording Studio' started by Nicky, May 22, 2016.

  1. Nicky

    Nicky On The Road Less Traveled Premium Member

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    I just acquired this vintage (60s-70s era) microphone from Maynar. It is presenting a mystery of sorts.

    It seems to work well, but needs a lot of gain. I've been doing research, and I can find a bunch of info on the CM654d, but NOTHING about the CM654a! A condenser mic should not work at all without phantom power, but the 654a provides a signal unpowered. If I add phantom power, it gives it just a tiny boost, not much. To get a good signal, I have to max out the gain on my interface. It sounds fine. I have not connected it yet to my Trident 80B preamp.

    I read where these Calrecs are unbalanced, and require a proprietary power supply or a custom built adapter cable in order to use phantom power. This 654a works just fine with a standard XLR. I'm emailing anybody I can find that posted anything about CM654s in the last 40 years.

    Any expert here know anything about the Calrec CM654a? :wave:

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  2. malcostuart

    malcostuart Senior Member

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    That is one excellent mic you have there but yes does require the propriety "box". They were produced in a small town called Hebden Bridge, in Yorkshire, England during the 70's. I don't know if their work shop even exists anymore but they had a fab recording studio over it which I used back then. It's a condenser microphone and if you can get happy with it you won't find a better. Wishing you good luck. :)
     
  3. Nicky

    Nicky On The Road Less Traveled Premium Member

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    I've already tracked down the successors to the old Calrec brand, and it dead-ends in Hebden Bridge. A gentleman named Ashley Styles has a website called Saturn Sound, and he seems to be the expert on old Calrec microphones. I sent him an email, but he has not responded.

    The old "box" power supply is available from time-to-time, especially on eBay in the UK. However, they all seem to use the DIN connector to the mic, not an XLR like my 654a. Strange...but searching out this stuff is half the fun.
     
  4. Nicky

    Nicky On The Road Less Traveled Premium Member

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    I sent an email to Hebden Sound, who acquired certain rights to the old Calrec mics and are now producing their own versions.
     
  5. yeti

    yeti Senior Member

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    Saturn sound used to sell a converter cable to use the 600series mics with standard 48V phantom power. They probably have the schematics to build your own. I can't imagine that it'd be hard to do. can't hurt to contact them.

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  6. Nicky

    Nicky On The Road Less Traveled Premium Member

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    Yep. I asked Mr. Styles at Saturn Sound if he would make a cable for me. I think the configuration of the OEM power supply is: "common "Earth/0v", +48v power and an "Un-Balanced" audio output. The +48v feed not being Phantom derived, but a single rail supply."

    How do I create a conversion cable using this information? Wouldn't I need some kind of transformer in the cable?

    Keep in mind that my mic has an XLR connector already, not DIN. How is it able to work now, connected to my interface, without phantom power? I get a decent audible signal.

    There's just a dearth of information available on the interwebz about the Calrec 600 series. Extremely difficult to find much.

    Ultimately, the key is to find out the difference between a CM654A, and a CM654C (or D). I haz a tired head. :shock:

    This is not an expensive mic, so I'm not obsessing about getting it to work correctly. I'm just a hobbyist who wants to restore and preserve a classic and important piece of history. I read where the BBC used the 600 series mics extensively in their broadcasts.
     
  7. Nicky

    Nicky On The Road Less Traveled Premium Member

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    Received a reply from Hebden Sound in the UK. They will inspect and analyze my 654A. They will repair or modify it to work with standard phantom power via XLR.

    That did not take long to find the right source for getting this mic to work properly. Will probably cost me a bloody fortune, but, what the hell!
     
  8. Nicky

    Nicky On The Road Less Traveled Premium Member

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    Mic has been tested, cleaned up and modified for phantom power. Will get it back from Hebden Sound in a couple of weeks. :thumb:
     
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  9. yeti

    yeti Senior Member

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    Good news, looking forward to your report upon return.
     
  10. Nicky

    Nicky On The Road Less Traveled Premium Member

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    I just acquired a companion Calrec CM652 FET condenser microphone. Works great, and I now know how to modify an XLR cable to acommodate its unique handling of phantom power.

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  11. MIKESTAR

    MIKESTAR Junior Member

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    Greetings, I just acquired a pair of CM652 c, how do I modify XLR cable to work these Mics.
    Luv -n- Peace!
     

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