On 26/08/13 14:06, Dave Plowman (News) wrote:
In article ,
Tim Streater wrote:
The arm assembly is mounted on wood so it's not a ground loop. Moving
the arm over the deck makes no difference to the hum - so I'd guess it
isn't coming from the motor. The wiring within the arm is single wires
- but then the arm itself should screen them? I've checked it is
grounded to my star ground point.
Where the wires leave the arm to enter the cartridge?
I'm not sure where SME grounds the arm. There are five wires going to the
connector on the base of the assembly (other end from the cartridge, as it
were) - one of which is the arm ground. They all disappear up the middle
of the pivot.

what you SHOULD do is to ground everything at the amplifier INPUT.
traditionally that means that the arm carries a separate earth for the
metalwork back to the amp chassis, which should be the ONLY part of the
hifi stack that is actually attached to earth.

And that ONLY at the preamp input itself.

in order to reserve the safety niceties, what the means is that other
equipment is only grounded electronically to cases by a 100 ohm
resistor if the cases are to be earthed, and that the outer sheath of
the phono/DIN plugs are NOT directly connected to mais earth on peripherals.


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