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Hum coming from Turntable

I need help in tracking a slight hum on my turntable.   I did narrow it down, and the cause of this would be my turntable.   Is this due:

1) cartridge not grounded properly 
2) cartridge wires are loose
3) turntable grounding is bad 
4) phono cable not properly shielded

Can any members/technical person that work on turntable can help me out.  Much appreciated!
128x128zipost

Showing 4 responses by holmz

holmz's avatar
holmz
2,328 posts
 
1) Does the cartridge even need to be grounded? The two wires come off if each coil
2) doubtful to be causing a hum
3) Seems the most likely to me

4) I would doubt #4 unless the RCAs were running along side of a power line going into the TT.
holmz's avatar
holmz
2,328 posts
 
Also add:
5) Magnetic fields caused but inductance loops from household wiring.
That one took me a couple of hours to figure out once. But one should rarely find that if the house is wired with Romex.


Does it do it whether the TT motor is running or not? 
holmz's avatar
holmz
2,328 posts
 
@zipost it has nothing to do with you household grounding.It is likely a magnetic field if it is 60 Hz.
But it could also be a ground loop.
holmz's avatar
holmz
2,328 posts
 
I would run all grounds to the same point.
If the cartridge is plastic or wood, then I am not sure how grounded they are??

If it is inducted field, rather than a ground loop, then it can get more complicated… but moving the switching supplies to another power strip might provide a data point?
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