grado hum

We had a Rega with a Grado that hummed; I found that neither the platter bearing nor the motor was grounded! Adding a wire was all that was needed- presto! no hum. The wire tied the ground of the motor to the platter bearing and the tone arm ground.

Most tone arms with a single-ended output will also have a ground wire for the tone arm ground.

In the case of a high output cartridge like the Grado, sometimes the cartridge can pick up hum from the motor if the motor is not also grounded to the arm. This is something that has to be added in some cases, like my example of the Rega above.

The wire was added to the case of the motor and went to the base of the tone arm. It was a bit of a trick because the metal case was an alloy that really didn't want to be soldered. I filed off some of the plating and used a good solder flux to assist with the soldering. This took the Rega/Grado combination from having an annoying background hum (usually only audible between cuts) to no hum at all.

This may be something that you will have to get a technician to perform, and I can't say it will work in all cases, but it is certainly worth a try!