Hum Problem with Grado


I recently helped my friend set up his VPI Aries Extended. He is temporarily using an inexpensive Grado ($80 Red?) cartridge but we are hearing significant hum. We grounded the table, which helped, but the hum is still very noticable. Anyone have experience with hum using a Grado and how can we solve this problem? Rest of the system is AR SP16 and VS110 w/ Proac Response 3s. Thanks.
dodgealum

Showing 2 responses by sidssp

This is odd. The only thing on the Aries that might cause hum is the motor but it is on the other side far away from the arm. It shouldn't cause the Grado to hum. Does the hum get louder as you move the arm towards the spindle? If not, I don't think the motor is the cause.

If it hums only during play, it is highly likely that you are hearing the mechanical hum caused by the vibration of the motor. This is a well-known problem of the Aries. To test that theory, you need to take the rubber belt off, lower the cart on the platter, turn on the motor, and turn up the volume. Now while the motor is running, carefully lift the motor up slightly and see if the hum goes away. If it does, you have vibration problem. An easy way to reduce it is to put a thick mouse pad under the motor. You can reduce it even further by replacing the stocked rubber feet with Tender Feet from Herbie’s Lab or run the motor through a SDS at reduced voltage.
Cserbell,
In your case, it was not caused by motor vibration. It was caused by the electric magnetic field generated by the motor since the Rega placed its motor under the platter near the center. You may try to reduce the hum by lining the underside of the platter with one or two layers of mu-matel sheet. Mu-matel can be cut in shape with a utility knife and can be mounted with double-sided tape. But they have very sharp edges (guess how I know). So handle with care.