Cserbell,
Good detective work, but the hum is not caused by physical vibration of the motor. It's caused by leakage of electromagnetic energy from the AC motor coils. EM energy travels through air pretty readily. That's why radio works.
Most cartridges are electrically shielded aginst EMI. Grado's are not, and are thus famous for humming. If you search here or on Vinyl Asylum for "grado + hum" you'll get a million hits. If you search for "most other cartridge names + hum" you'll get far fewer.
Possible solutions:
- shield the motor, try wrapping some foil around it
- shield the Grado, as mentioned by Ramstl
- dump the Grado
Good detective work, but the hum is not caused by physical vibration of the motor. It's caused by leakage of electromagnetic energy from the AC motor coils. EM energy travels through air pretty readily. That's why radio works.
Most cartridges are electrically shielded aginst EMI. Grado's are not, and are thus famous for humming. If you search here or on Vinyl Asylum for "grado + hum" you'll get a million hits. If you search for "most other cartridge names + hum" you'll get far fewer.
Possible solutions:
- shield the motor, try wrapping some foil around it
- shield the Grado, as mentioned by Ramstl
- dump the Grado