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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
mugrug12's avatar
mugrug12 OP
10 posts
 
I think also maybe I don't fully understand the purpose of tonearm damping. If the mass/compliance is well
matched producing the correct recosnance, like my setup is, then what's the damping fluid for on the later models?
totem395
196 posts
 
then what's the damping fluid for on the later models?


To allow more flexibility in choice when using lower compliance cartridges.
tubegb's avatar
tubegb
59 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.
mugrug12's avatar
mugrug12 OP
10 posts
 
Thanks that's helpful guys. Is bearing chatter possibly what I'm experiencing then? Or I'm barking up the wrong tree maybe. Have you guys ever owned a thorens td125mkii or BW tonearm? Time to google "bearing chatter" here I go....
tubegb's avatar
tubegb
59 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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