Posted by hurdy_gurdyman [ 4.229.162.155 ] on March 07, 2007 at 12:22:57:
In Reply to: Idler Drive and my Rek-O-Kut project posted by hurdy_gurdyman on March 06, 2007 at 09:04:59:
I found another problem I had overlooked before. I was playing a record at a good room filling volume today. When I lifted the arm from the lead-out groove, I noticed a reduction in a slight hum, different than the electrical hum I had had. I played with this a while, both on the lead-out and the lead-in groove. Next, I started just the motor without engaging the platter drive. Exact same thing happened. Definitely not the drive system. What I'm hearing is mechanical motor noise. I can't hear this acoustically while listening to the motor with my ear by the chassis, as all I can hear is a whisper of sound. Hmmm... I dug out the Dual and listened to it, doing the same experiment. It had the exact same sound with just the motor running. I've listened to Duals for many years and had not noticed this before. Probably if I had heard it I had just thought it was recorded noise from the record cutter. I don't know if this is audible on belt drive, as my AR doesn't have a tonearm at the moment. The noise level is low enough not to be noticed at all while playing a record. I'm thinking that those old rubber grommets on the motor mount may be dried out and not isolating good anymore. I'll see if I can locate some locally from a hardware store. Not sure what I'm going to do if I can't find new grommets. Live with it, I guess. I am going to try and mass load the motor when I have the chassis removed to install veneer. This may get rid of a lot of it. It's not bothering me at all while playing music. I still like the music better than on any of my other tables. I guess it's just one more challenge!
Dave 
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