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Grounding problem in a slimmed down recordplayer.

Discussion in 'Audio' started by Mockarutan, Jul 14, 2018.

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  1. Mockarutan

    Mockarutan

    4
    0
    Jul 14, 2018
    So I'm rebuilding an old recordplayer, sort of sliming it down and removing the "big box" and putting away the electronics inside so I can have only the record and the arm visible by itself. I have gotten everyting to work, but the grounding is all wrong so I got quite a bit of humming. If I touch the big metal disk the record is laying on (at least 1 kg of metal), I get a lot less hum, but still some.

    Before it was not grounded thought the outlet, but it was grounded via the amp, which I don't have anymore. It also had a pretty big and heavy metalplate in the bottom, don't know if that could have helped in anymay, but I thought i mention it since I removed it. Now it's hooked to an active speaker via a new RIAA amp I bought for this and the ground cable is connected to the RIAA amp. The RIAA amp has a specific grounding hook, but it's not grounded thought the outlet either.

    So, this is not black magic to me, but almost, so I don't really know how to approch this problem. Can anybody help me out? Thanks in advance!
     
  2. Ylli

    Ylli

    271
    72
    Jun 19, 2018
    So all you have left of the original 'record player' is the turntable and the tonearm/cartridge, right?

    Connect the metal from of the turntable to the ground block on the new amplifier. then... what kind of input does the amp have - differential, single ended, RCA socket, etc?

    And was this a cheap record player - one with a crystal/ceramic cartridge, or is it a higher end unit with a magnetic cartridge?
     
  3. Bluejets

    Bluejets

    3,784
    783
    Oct 5, 2014
    You will need to run the wiring from the pickup arm to the amplifier in shielded cable.
    Connect the shield to the negative rail on the amplifier only, do not connect the other end anywhere else.
     
    davenn likes this.
  4. Mockarutan

    Mockarutan

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    Jul 14, 2018
    I have all the electronics left, just not in the box. The motor, arm, electronics and mechanics associated are all left, it just does not sit in the box (with the metal bottom) anymore. So I have the ground cable left. But I now I tried to just connect all "metal things" left in the system (not only the ground wire) to one wire and then I tried connecting that wire to different things. Connecting it to the new RIAA groound hook does lower the humming a bit, but it's not gone. Connecting it to my radiator, no difference. But if I connect it to the big metal plate from the original box, it goes away completely... So do I need to keep that metal plate connected somewhere hidden? Haha..


    This is basically what I've tried, but not with a shielded cable. And it's not a big amp, just one of those small RIAA amps. Then it's connected to a pair of these: http://m-audio.com/products/view/bx8-d2 . But I'm gonna get a hold of a shielded cable and try that! But do you have any comment on my super getto try I described above?
     
  5. Ylli

    Ylli

    271
    72
    Jun 19, 2018
    If you are going to be still using the old electronics, I would assume the 'RIAA Amp' is just a preamp. does the cartridge you are using need a preamp? Do you have a link to the RIAA amp?
     
  6. Mockarutan

    Mockarutan

    4
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    Jul 14, 2018
    It's this one: https://www.kjell.com/se/sortiment/...CqnqJO2raN7k9-o_XXBoCZykQAvD_BwE&gclsrc=aw.ds

    And now I feel kind of stupid, because I realize that the ground the RIAA (pre?) amp has is probably for it's grounding, so it's suppose to be connected to a real ground? I have some experiments to do when I get home, might have all the gear I need to fix it, will give update here!
     
  7. Mockarutan

    Mockarutan

    4
    0
    Jul 14, 2018
    Update! I think everything is fine! I was just a bit stupid... the ground hook on the RIAA was not to ground stuff in, but for grounding the RIAA itself. So i connected that ground and all the grounds from the record player to a screw on my active monitors. Just loosened a screw, rubbed of some of the black paint on the screw and hooked the ground to that and tada!

    Thanks for the help!
     
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