In article ,
tony sayer wrote:
It's the pick-up to on board pre-amp where the hum occurs. Pre-amp to main
amp control unit is fine.


Right..

You say this amp is a "balanced" input is that transformers or
electronically balanced?.

Electronic. Uses an SSM 2017 at the front end.

Either way what happens when you simply short out the inputs with a
total short then say 10 ohms then 100, any reduction or rise in the
"hum" level?. Do that at the input terminals presumably XLR or similar
then repeat the same on the cartridge leads on the SME arm where the
cart goes.

No XLRs. The pre-amp board is mounted only a few inches from the pickup
arm. The SME arm has a plug and socket connector, which is hard wired to
the PCB. Unplug that, and the hum totally disappears. No need to provide a
dummy load.

Of course each lead from each pickup coil left and right that is, is
connected via two isolated from any ground leads is it not?..

Each coil goes to a balanced input. No other connection.

What I might try is removing the internal wiring to the arm, and see if it
is twisted. I suspect not.

--
*Speak softly and carry a cellular phone *

Dave Plowman London SW
To e-mail, change noise into sound.