Hum from Empire 698
normansizemore283 posts"Sounds like the cartridge is picking up a open ground loop..." That doesn't make any sense. A ground loop and an open ground are completely opposite things. A ground loop is the result of two or more paths to ground with different voltage potentials. An open ground is an open (incomplete) circuit. The most likely cause is a cartridge that susceptible to motor hum. Grados are especially vulnerable to hum fields. You might also check your arm wiring. That there is no hum when it is at rest is no assurance the wiring is ok, because of course the wiring must twist to some extent as the arm pivots. |
rwwear, Sounds like the cartridge is picking up a open ground loop from the motor. When the stylus is moved over the platter (i.e. in closer proximity to the motor) your getting hum. 60hz I would imagine. Try placing an additional rubber matt on the platter and see if the hum is reduced or disappears. I am flying blind here, but I would think that your issue is in the motor, since you properly rewired the arm. If the hum experiment above is sucessful, then a motor rebuild or replacement is in order. Being that it's making noise (is should be dead quiet), that is where I would look. Good luck, the 698 is a wonderful table and worth the effort to sort matters out. Norman |
