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Rumble question- Thorens/black widow

Hello, I've been a reader  for a while but this is my first post. Thanks in advance for any help/advice!

my turntable makes a very soft rumble sound mostly audible between the tracks or in very soft passages of music. I know the noise floor will never be like a cd but I would like to address this as I don't hear it in my previous  turntable which is a cheapie. 

I have a thorens td125mkii w an infinity black widow tonearm. I suspect the sound is actually due to the tonearm. That's because it seems to be microphonic, because if I gently rub my finger on any part of it, you can hear the gentle rubbing sound get picked up. This is the first black widow- it doesn't have damping trough.  

-do you think the rumble is from lack of damping or maybe not?
-can I diy damp the arm easily to test it?
-or what else might be the problem? It has original wiring but theres no hum or feedback at all. 

Thanks and sorry if this post was long!
-David 

128x128mugrug12

Showing 3 responses by tubegb

tubegb's avatar
tubegb
187 posts
 
It may make sense to address the motor noise/vibration first? Admittedly it has been a long time since owning a Thorens turntable, but I don’t recall it having as much audible noise as you describe.

 

The first generation Infinity Black Widow tonearm with knife-edge bearings requires the use of a low mass/high compliance cartridge for it to perform at its best. (Back in the day think Micro Acoustics, ADC, Grace, etc.) I would not recommend a “home brew” damping strategy. This does not necessarily address your issue but should provide the opportunity for best tonearm/cartridge performance.Watch those original wires, super fragile as you probably already know.


tubegb's avatar
tubegb
187 posts
 
The arm in its early iterations was susceptible to what was called at the time “bearing chatter.” As totem395 mentions the damping fluid tray served to increase cartridge compatibility. It also helped to alleviate the potential for bearing chatter.
tubegb's avatar
tubegb
187 posts
 
Yes, absolute first-hand experience with the Infinity tonearm many years ago. One of the best combinations was with the ADC XLM II that you mentioned purchasing NOS. My turntable at the time was a Kenwood KD-500, which was direct drive and having a fixed suspension. So, very different from the Thorens. Since what you’re describing is while the tonearm is not in use it is unlikely having to do with the bearings.
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