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Re: Idler Drive and my Rek-O-Kut project [message #13309 is a reply to message #13298]

Wed, 07 March 2007 11:22

hurdy_gurdyman
Messages: 416
Registered: May 2009

Illuminati (1st Degree)

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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Re: Idler Drive and my Rek-O-Kut project [message #13311 is a reply to message #13309]

Wed, 07 March 2007 16:32

hurdy_gurdyman
Messages: 416
Registered: May 2009

Illuminati (1st Degree)

I've had more surprises since my last post. While checking things out, I noticed I had all the tonearm wires backward on the RCA sockets on the back of the plinth. I had to move the plinth/chassis assembly around to get to it for soldering (not an easy task with the rubber balls I'm using for feet). Once done, I put the whole thing back in place. First thing I noticed was that the motor hum was barely noticeable now! I am perplexed! The only thing I can think that could have been effected is the power cord could have been caught on the motor and was dis-lodged when I moved everything. Nothing else has changed. Now, when I leave the motor on but don't engage the platter, I hear little difference between the stylus sitting on the record or lifted off. I may never know for sure what happened, but all is well now. No more nasty mechanical hum. Electrical hum changes a lot according to how the IC wires are positioned behind the equipment console. The wires are 10 feet long Monster Cable Interlink 400 MkII. I really need shorter ones for this.

While playing around with everything, I installed my old Grado Black and was pleasantly surprised to find no more electrical hum than the Shure M91E had. Very cool! I like the Grado's sound better. I never cease to be amazed at how musical the primitive AR-XA arm can sound.

At this point, I have no complaints. Until the Black Widow arrives, this will do me just fine.

Dave

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Re: Idler Drive and my Rek-O-Kut project [message #13313 is a reply to message #13311]

Fri, 09 March 2007 08:13

hurdy_gurdyman
Messages: 416
Registered: May 2009

Illuminati (1st Degree)

I mentioned earlier that electrical hum seemed to be very wire position sensitive. I found the problem. It seems the Monster Cable Interlink 400 MkII I'm using doesn't like being a phono stage wire. I'm not sure if it's the way the wire is built or the 10 foot length. I traded places with the preamp out wire, a blue colored IC that came with my Jolida CD player that's three feet long. Now, the hum is lower than ever and makes only minor differences when moving it around.
At this point in time, I can safely say that this set-up is by far the best sounding of any turntable I've ever owned in about forty years of audio passion. Hum is as low as I could ever get with my Denon DP-75, and mechanical noise is on a par with my AR-XA. I can hardly wait to get the Black Widow arm, now. Also impatient for Spring to get here so I can put a finish on it. Dang North-land weather, anyway.