Hum Problem with Grado

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

I recently bought my VPI Scout and set it up with a Grado Red just to get me going. I noticed a hum but only after a rather loud listening session where I left the volume way up and went to change a record. I was only a few feet from my speakers and noticed it. Turning the volume way up increases the hum...but I would never even consider listening at those levels. I tried grounding the table to pre-amp, less humm. I switched from my Kimber Hero's to AQ Diamondbacks and got even less hum, but sound was not as good.

Right now I still get an audible hum at high volumes when I am close to the speakers. Normal listening is ok. I'm sure it degrades the sound some and because of this will more than likely change to a new cartridge sooner than I thought.

Same problem for me with my VPI M4 and high output Grado Sonata. Not a huge hum, but motor induced and noticable at high volume levels. I shielded the motor assembly with two layers of mu metal and the hum is pretty much completely gone, I'd say 90% reduced. I could only hear the hum on the last three inches towards the spindle when not actually playing. But you know it's there. Easy to do and effective. A very good tweak for me because the cartridge wasn't cheap. Good listening.

http://www.lessemf.com/mag-shld.html