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In Reply to: RE: Anyone interested in an improved SL1200 main platter bearing? posted by tubesforever on May 18, 2009 at 00:12:00
But since I don't have many hours on it (and thus don't have a good "feel" for it yet) I wouldn't be able to give you any useful feedback.
See you at Mike's!
Jim
Follow Ups:
Ribs...yummn I am getting hungry already.
I am bringing some toys with me. Cheers!
"Music Matters" Help support our schools music programs.
a silicon carbide ball? I was shocked at the difference between the SS ball and the SC...the accumulative effects of separating the motor from the chassis, changing out the thrust bearing's ball, big spikes as "feet" and the 12.7 pivot point on the JMW 10 created a table I'd put up against anything out there. It is incredible!
I'm looking forward to "showing you do its THANG!" Of course, you're bringing something that I'll cry about...but the stock Piccolo ain't no slouch, either.
There is no such thing as too many records.
There is just too little room for them!
The receipe will be a mystery for a while. I really need to get some alpha site bearings out to folks that have a good reading on their SL1200 turntables.
Good, bad or ugly the SL1200 bearing is a weak link. Improving it will be an interesting follow up post.
I don't have a table of my own to evaluate, so I really need about 5 inmates to let me know how the results sound in their systems.
Luckily this is not an irreversible modification. I can always return this to a chrome steel ball and sintered metal thrust plate. This would be a slight improvement over the stock machined surface.
Cheers!
"Music Matters" Help support our schools music programs.
Your statement that replacing the machined surface with a chrome steel ball would be an improvement is quite wrong.
If you look at the bearing you will see that it is machined as an oblate hemispheroid to increase the effective radius at the contact point, thereby decreasing the load stress and increasing the toughness of the bearing. If the machining is done the right way the apparent surface roughness is not very important as the apparent roughness is orthogonal to the direction of motion.
Bottom line: Technics engineers really know what they are doing. It is important to understand why they made a particular decision before reversing it.
Mark Kelly
Regarding the bearing materials, machining quality and design criteria, this bearing is built to be a nearly indestructable piece perfect for high utility studio and DJ applications.
This bearing provides lower opportunity for Brinnelling given the rubber damped vinyl sub plinth which communicates a lot more pounding than a suspended platter assembly. The SL1200/SL1210 was designed for easy and trouble free mobility which is perfect for a studio or DJ.
Replacement bearings are sold between 75-100 dollars and are available from Technics. They are very simple, very plain, and easy to replace.
Nothing I do in my trials could in any way impact the overall value of the table to its owner. The modified bearing could be tossed out and replaced with a factory bearing if the alpha user does not like the results.
If the modification is successful, I could easily machine plain steel, stainless steel or even a silicone nitride ball to the same geometry of a stock Technics bearing if the table is going to be used in high mobility applications.
I could even use graphite impregnated space age plastics as a thrust surface that would be superior to the stock Technics bearing.
If you want a sample of the thrust surface material I plan to evaluate, I am happy to provide one or several to you for your own testing. I will do so at my own expense. I have no agenda with this test. I am looking for ways to achieve quieter noise floors for my friends spinning an SL1200 turntable.
I have CDR test recordings of similarly improved bearings if you want to hear the results in your own system. My own turntable bearings show no sign of wear after more than a year of daily spinning and I am using a platter at least twice as heavy.
"Music Matters" Help support our schools music programs.
I'd take a sample. I do friction and wear testing for a living. Heck, send me some of the technics stuff and I'll test that too.
I've gotten so much through various forums, that I really would like the opportunity to give back.
If you have not done so, email me at jim_howard_pdx@yahoo.com. I am happy to send you several pieces for your evaluation. I can outline my project, the desired results and some additional details that can make this more fun from a testing/performance perspective.
"Music Matters" Help support our schools music programs.
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