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Thread: Loud Hum Through speakers when playing Dual Turntable

  1. #1
    Join Date: May 2018

    Location: Ireland

    Posts: 29
    I'm Stephen.

    Default Loud Hum Through speakers when playing Dual Turntable

    I'm very close to upgrading my system, mainly to play Vinyl, but will have to start with either an amp or turntable.

    As mentioned previously, I have a Dual 505 turntable and a Cambridge Audio Azur 540A amp, which has a gentle hum when turned up to 3/4 power, which was necessary to hear vinyl records even via a preamp, but not for CD via my Monitor Audio Bronze B2 speakers.

    I was very close to deciding that the amp was the first thing to upgrade, but today, while playing the turntable the gentle hum became a very loud buzz through the RH speaker. This stopped when I put the tonearm back on its rest and did not happen at all with the CD.

    Am I right to think, now, that the problem is in fact with the turntable? In which case, that's the first upgrade to make?

    Thanks for any suggestions,

    Stephen

  2. #2
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 34,495
    I'm Geoff.

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    You have an earthing issue by the sound of it. That should be simple enough to sort.

  3. #3
    Join Date: May 2018

    Location: Ireland

    Posts: 29
    I'm Stephen.

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    Quote Originally Posted by walpurgis View Post
    You have an earthing issue by the sound of it. That should be simple enough to sort.
    Thanks Geoff, any advice on how I do it. I have the ground wire from the Dual securely wrapped around the screw on the preamp, in fact double-check it today.

  4. #4
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 1,140
    I'm Andrew.

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    Quote Originally Posted by Valentiaman View Post
    ... today, while playing the turntable the gentle hum became a very loud buzz through the RH speaker. This stopped when I put the tonearm back on its rest and did not happen at all with the CD.
    Either a wire within the tonearm has broken and moving the arm causes an intermittent contact (hence the loud buzz stopped when you put the tonearm back on its rest), or the tonearm has a mute switch which silences the cartridge when the arm is on its rest (hence the loud buzz stopped when you put the arm back on its rest).
    Either way, the arm wiring needs to be checked.

  5. #5
    Join Date: May 2018

    Location: Ireland

    Posts: 29
    I'm Stephen.

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    Quote Originally Posted by RothwellAudio View Post
    Either a wire within the tonearm has broken and moving the arm causes an intermittent contact (hence the loud buzz stopped when you put the tonearm back on its rest), or the tonearm has a mute switch which silences the cartridge when the arm is on its rest (hence the loud buzz stopped when you put the arm back on its rest).
    Either way, the arm wiring needs to be checked.
    Thanks Andrew. I'd be fairly sure (but not certain) that the old Dual doesn't have a mute switch in the tonearm, and I'm leaning towards the wiring problem. I think I have to accept that my Dual has seen better days (I bought it second-hand in 1985). In which case my decision is made easier and I'm going to upgrade the turntable first...I'll probably buy a Rega Planar 1.

  6. #6
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 34,495
    I'm Geoff.

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    If your Dual is an earlier one, it likely has a cartridge carrier that slots into the headshell. The little metal tags/tabs on these can make poor contact sometimes. That could be something to look at.

    I'd not give up on it too easily. The 505 is a decent enough little turntable.

  7. #7
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 1,140
    I'm Andrew.

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    It should be easy enough to check the wiring before rushing into an unnecessary purchase. With the cartridge disconnected there should be no contact between the four wires at the headshell. Then insert the right channel phono plug at the end of the arm cable into a shorting socket and there should be continuity between two of the wires at the headshell. Repeat for the other channel. Check it still works when the arm is moved.
    I'm not sure how easy it is to replace the wiring if it's faulty without seeing it, but I suspect it will be quite fiddly.
    Still, at least you would know for sure what the problem is.

  8. #8
    Join Date: May 2018

    Location: Ireland

    Posts: 29
    I'm Stephen.

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    Thanks again Geoff and Andrew. To be honest, I think I'm ready for a new turntable and probably an amp too! I'm getting too old not to treat myself to decent sounds!

    This is the headshell with the cartridge attached.


  9. #9
    Join Date: Apr 2009

    Location: Near Saffron Walden, Essex

    Posts: 5,801
    I'm Dave.

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    Get yourself a P1, sit back and enjoy the trouble free sound.

  10. #10
    Join Date: May 2018

    Location: Ireland

    Posts: 29
    I'm Stephen.

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    Quote Originally Posted by hifi_dave View Post
    Get yourself a P1, sit back and enjoy the trouble free sound.
    Going to the London Saxophone festival weekend after next and when I get back, I'll be placing the order.

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