Saturday, June 11, 2011

Getting Rid of the Grado Hum

Type "Grado hum" into Google and you will immediately find numerous discussions about the legendary Grado hum, which occurs with some turntables, most notably the Regas. Like many people I had thought that the hum issue was somewhat exaggerated as I had used a Grado Gold1 with a Rega and found the hum produced to be virtually inaudible. This was with the Grado Gold1 mounted on an RB250.

Recently, I purchased a Grado Sonata and mounted it on a Michelle Tecnoarm. Unlike the RB250 the Michelle Tecnoarm is not internally earthed and has an external earth wire that clips onto the earth terminal of the phono stage amp. Set-up like this the Grado Sonata hummed big time, so much so that I was feeling like taking the Sonata off and reselling it. Searching the internet did not reveal any sure fire solutions. Mu-metal shielding around the motor had worked for some people, but not for others.

Earthing the tonearm to the motor had also worked for some, but it didn't work for me. However, while attempting this, I noticed that the hum reduced in volume the closer I moved to my integrated valve amp. So I clipped the Tecnoarm's earth wire onto the metal front plate of the amp and the hum vanished instantly and completely. Even at full volume there is no hum audible.


  1. So glad you posted this. I have a Michell Gyro SE with a Michell Technoarm and an Ortofon rondo red cartridge feeding a Tom Evans Microgroove + phono stage which in turn goes to an integrated AVI S2000M integrated amp. I was having the same issue but have now linked the ground from the phono stage to one of the screws on the amp's chassis and Bob's your uncle, job done. Thank you so much.

  2. Hi Tony

    Glad this worked for you.

    I now as standard double earth. I run the the tonearm earth to the phono stage earth screw and then run a second wire from the phono earth to a screw on the amp chassis. This has worked on the occasional random hum that arises and is also a good solution when the earth from the turntable / tonearm isn't long enough to reach the amp.