Linn Bedrok LP12 Plinth Upgrade

On audible noise between tracks, my brand-new Decca recording of Beethoven's Triple Concerto is very quiet on the long lead out tracks but has noticeable murmerings between the tracks, about in the middle of the quiet moments!

@lewm 

Don't you see the irony that you make that 149th comment as someone who doesn't even own an LP12.

The most precise manufacturing tolerance I ever encountered was the extremely tight shaft and bearing of my Thorens TD124.

You attach the shaft on the bottom of the 4.5kg (9.9lbs) cast iron platter, place it in the bearing, it takes several minutes for over 10lbs to fully lower, the air has to escape, push it, it is like an air spring, it bounces back. I will never forget the 1st time I put it back in and experienced that heavy platter floating on trapped air.

The many parts of it’s SME 3009 II Tonearm are such that required movement is easy yet impressively tight

I watched this video showing the assembly of Linn’s TT in a Bedrock Plinth, and I was quite surprised at the looseness of parts, at minute 5, the platter/shaft drops into the bearing, finishing with a clink or clunk, it happens twice and then, the tonearm post goes into the mount like a truck driving thru the Holland Tunnel at minute 6.

The Bedrock’s best feature seems to be captive threaded inserts to fasten the top and bottom metal plates, you can see it’s just an edge frame with corner blocks, not really a plinth in my thinking.

https://www.youtube.com/watch?v=SqP4eHBSlI4&t=2s

I was/am shocked to see the lack of precision, I always assumed fine manufacturing tolerances were part of Linn’s success.

That TD124/SME 3009 II combo combined with the V15VxMR microridge on beryllium produced the most impressive, tightest bass I ever experienced (tracking at only 1.0g). I’ve never forgotten or experienced it since having to part with it because it’s bearing was too succeptible to vertical movement from my springy wood floors.

I always felt quite certain it was due to ALL groove modulation being transferred to the cartridge, none escaping thru movement in the arm and TT. I have to believe that cannot be possible with the loose platter shaft and tonearm post seen in that video.

@elliottbnewcombjr The new Karousel bearing is reportedly machined to within 5 microns ( is that a lack of precision???). What do you believe your Thorens bearing is machined to?

BTW, you do realize that your SME example relies on a knife edge bearing and all that it brings?

newton-john. Of course I see the irony. Which is why I posted.  But the title of the thread indicates that the Bedrock is the subject, which, unless I missed something, you also do not own. We have that much in common. Anyway, I hope you know I bear no ill will toward the LP12 or the Bedrock. I originally commented in order to clarify for myself what the Bedrock is made of and how it is fashioned. Our of curiosity. My own preferences in TTs are pretty much the opposite of an LP12.