[78-L] turntable hum mystery

[jeffrey smedbron]

Could that be Hall effect from the close proximity of the metal turntable surface beneath the record. Maybe try taking off the needle and hold the cartridge just above the platter running without a record on and see if it is present.   




________________________________
 From: David Lennick <dlennick at sympatico.ca>
To: 78-L Mail List <78-l at klickitat.78online.com> 
Sent: Thursday, November 8, 2012 4:54 PM
Subject: Re: [78-L] turntable hum mystery
 
At times I've had the opposite situation..hum disappears when I place the 
stylus in the groove. My Technics SP15 has a ground wire for the turntable and 
another for the tone arm and I found when I disconnected one of the grounds 
(can't remember which one), hum disappeared. Also when I stopped playing 
records by the Tuvan Throat Singers.

dl

On 11/8/2012 5:46 PM, neechevoneeznayou at gmail.com wrote:
> Listers,
>
> Last time I posted about hum on my turntable, it was solved by checking
> the ground connection. It was loose, and tightening it made a huge
> improvement.
>
> Later I was thinking I was hearing much hum from the records. Surely
> they didn't record that much hum in so many records did they? Upon
> further investigation, it appears not to be from the records. It is only
> when the table is on and the stylus in contact with the record. Lift the
> stylus even the tiniest bit and the hum goes away. Turn the thing off,
> even with the stylus on the record, and the hum goes away.
>
> So how is the hum getting into the system? Neither vinyl or diamond are
> conductors of electricity. So I've ruled that out. Bad p.s. caps giving
> off EMR that the cartridge is picking up? Seems unlikely, in that
> picking up the stylus even the tiniest bit causes the hum to cease. If
> the leak were in the air I would expect the hum to remain as long as the
> cart was within a certain proximity.
>
> Whaz goin' on here?



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