Dual 503-1 Low Frequency Noise

[Robel]

I just hooked up my old Dual 503-1 turntable after shelving it for a few years. It has an Epoch II cartridge. It sounds good, but after about 15 minutes it starts emitting a very loud low frequency noise. I have the table properly grounded. It is connected to a Marantz AV7701 pre pro. I had this problem a few years ago when it was connected to my McIntosh C28 preamp. I think that's why I put it on the shelf. Any of you turntable tweeters have any ideas about root cause? I want to get back into vinyl.

As always, your advice is greatly appreciated!

 

[wrbear]

I had a grounding problem on mine. This may not be the problem but I touched it around the wiring on the head which made a distinct change in the sound. It was an oxidized grounding connection due to age and storage. Cleaned it and no problems. This might be a different problem but worth a try.

 

[lini]

Robel: You'll need to further diagnose that. For example: Does the noise level vary with tonearm position/playback radius? And does it make a difference, whether the arm is lowered to the platter or in lifted position?

And how exactly does that low frequency noise sound? Like a ground hum? Or rather like something mechanic interfering? And when you write "it starts emitting (...)", would that mean acoustically by itself - or rather via the playback chain, i.e. through your speakers/headphones?

Greetings from Munich!

Manfred / lini

 

[Robel]

Thanks everyone for the suggestions. I don't really know much about turntables other than how to operate them. It sounds like I will have to take it apart to check the ground wire attachment. But the ground could definitely be the problem as this TT was purchased in 1989. It does seem odd to me that the problem presents itself after several minutes of operation. The noise most definitely is coming through the entire system and not just emanating from the table itself. I can eliminate the sound system(amp, preamp, speakers, etc) as a variable as this problem existed on the McIntosh gear, too. Lately, I've been toying with the idea of getting back into vinyl, hence my getting the Dual out of storage. If the problem cannot be resolved I may have to look into one of those Thorens tables! Thanks again, everyone! And Manfred, thanks for weighing in from Munchen! Great city! Especially fond of the Haufbrau Haus!