2. analog
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Which EPA-100 bearings?

I picked up a nice EPA-100 a few months ago in excellent cosmetic and functional condition. The bearings seem good, as far as I can tell—it passes the WallySkater stiction test with aplomb, anyway. And it sounds remarkably alive and resolving with no obvious behavioral issues.

Still, given the famous fragility of its ruby bearings and the age of its internal wiring, I suspect it can sound even better with some refurbishment—new bearings, new wiring, whatever it needs. I think this tonearm is good enough to warranty the investment. 

JP at Fidelis Analog has graciously agreed to work on it. He offers, and prefers, silicon nitride ceramic bearings (Si3N4) for both performance and longevity. He also has a supply of ruby bearings for those who prefer to keep it original. So, I have a decision to make. I like the idea of keeping it stock but I want the best performance and, most important, sound.

Has anyone compared the sound of Si3N4 bearings to the original ruby? Has anyone replaced the ruby with Si3N4 and regretted it?  I’d like to hear some hands-on, ears-on experience before I make the choice.

Thanks!

wrm57
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rauliruegas
12,814 posts
 

Dear @wrm57  : I owned the 100 and the 100MK2 functioning in perfect condition.

If you want to internal re-wiring go a head, recomended.

Now, for the ruby bearing please do it your self next question:

ceramic bearings always exist even when the EPA 100 was designed: do you think that been designed by Technics that if ruby were not the best quality performance bearting tonearm design they made a mistake when choosed ruby?, Technics is second to none even today and they does not makes that kind of design mistakes. In those times the japanese competence was really hard on  tonearms.

 

Btw, I owned  the Mission top of the line that came with ceramic bearings and was not good enough till I changed by stellness ones.

 

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

tablejockey
3,779 posts
 

'Has anyone compared the sound of Si3N4 bearings to the original ruby?"

Drag coefficient has  a sound?

pindac's avatar
pindac
2,414 posts
 

Ruby's and Sapphire are fragile and may be difficult to ensure the parts produced from it in a Tonearm or TT, will be intact at the end of a Long Freight Journey.

 Si3N4 is commonly seen used as a bearing in place of a Steel Ball, the Si3N4 is known for its robustness, and is seen at interfaces where impact damage is a risk.

https://forum.audiogon.com/discussions/silicon-nitride-vs-ruby-bearing-for-rega-p5   

  

wrm57 OP
975 posts
 

@pindac , thank you for those links. Very interesting, especially moisin’s comments.

@rauliruegas , I appreciate your experience in this matter, as in others analog. Is it that you think the ruby material (actually sapphire, as it turns out) has a preferable sound to the Si3N4? I ask because the hardness and density of the two materials seem virtually the same, which means their friction and stiction will be pretty close to each other when the bearings are unflawed, which means their mechanical performance should be pretty much the same. So what’s left? Whence your strong preference for ruby?

 

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