grado reference statement hum

where does one obtain mu metal?

Is the motor on your Wilson turntable directly underneath the platter? What I have seen some do in the past is to place a thin sheet of aluminum foil underneath the turntable mat. This will create a shield in-between the cartridge and the EMF fields being created by the motor.

This is ineffective if the motor of off to the side. But if it is directly underneath, it may be an inexpensive way to create some shielding without breaking the bank.

Had the same experience with Grado's when I used them many years ago. I guess they still choose to not include shielding. I believe lead creates a good shield, but is obviously heavy. I wonder if you could address the shielding at the platter and or mat. There was a company called Merril that used to make mods for the classic AR turntables, one of which was a motor shield since those motors were unshielded and really did a number on the Grado's. The metal plate they sold to shield the motor attached to the plinth and did offer some improvement, but my Grado still had quite a bit of hum even with the plate. I also swapped out my motor with the Merril modded motor but don't recall that helping as much as the plate did. Otherwise I always liked the Grado cartridges. I had three as I recall, the best of which was in the signature series. All MM cartridges. On the same table I tried a Sumiko MM and got no hum at all.

Good luck!

Marco

PS A quick search on magnetic field shielding (MU shielding) turned up This Site. I'm sure you can find others.

woo hoo mu metal works.....thanks all

Hum on my the statment (when the arm moves closer to the motor) completely gone when ac motor was replaced by dc motor. Magnetic filds are night mare for grados. ph-1 is also very sensitive and did not like any heavy electric powers (transformers, wires) around.