Question Feedback Buzz/Hum When Turntable Turned On

Discussion in 'Hi-Fi Stereo Systems & Separates' started by nfisher, Jul 11, 2018.

  1. nfisher

    nfisher
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    Basically when I turn on the turntable the amplifier emits a feedback buzz/hum sound, that is constant as long as the turntable is on or until the volume is turned all the way down. At first I thought it was a mains issue but I moved the system around my home and to different outlets and it made no difference. It seems to be linked to the tone arm as every time I lift it the volume and pitch of the buzz/hum changes. Any ideas? I just moved and this is a new problem.
     
  2. Rachel H

    Rachel H
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    With the amp on and volume at listening level what happens when you touch the tonearm cable in places or touch or twist the RCA plugs?
     
  3. dannnielll

    dannnielll
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    They are good questions to ask, the next one is to check that there should be a single earth point linking the turntable to the amplifier. If the leads from the turntable .. eg RCA types , have a braid ,this normally acts as the earth point and or a shield. If there is an additional connection on the back of the amplifier , then it can be made, provided that the braid only makes electrical contact at on end only.
    The majority of hum problems is having two earth points . The earth wire can act as a loop. The larger the area the loop occupies, the greater the amount of hum current produced. . Even the earth return green yellow wire in a plug can act as part of the loop.
    Phono systems are the most susceptible to this because it is traditional to send a very low level signal of a few millivolts and high impedence , along a metre or so of wiring BEFORE it gets amplified. And it has to be amplified by nearly 1000 fold. The shield is for electrostatic protection, and should have a connection at only one end... . The 4 wires of the cartridge are are looped together to reduce the area of their loop, but if there is another wire also connected, the loop is huge..
     

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