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LP eccentricity, spindle hole center,The fix??????

Hi all,

I'm one of those audiophiles, 67 years of age, that wonders about the effect of the accuracy of the center hole. Some of the LPs I put on the TT have play due to a center hole that's punched out of round, too large or what ever.

I'm playing a record on a Denon 308 direct drive table using a system devised by a LJT Mfg in Canada to reduce eccentricity and help flatten warped records using a peripheral ring clamp in conjunction with a 1420 gram spindle clamp. The trio comes along with a cnc machined polycarbonate centering disc that straddles the record after the clamp ring is set registering on the outside diameter of the record. I can feel play regarding the center hole as I implement the OD centering device. I'll measure it tomorrow, just a few thousandths. The music sounds fine to my ears but I wonder what the relationship is to the record grooves, the outside diameter, and the center hole.

A while back a TT was made that had an extra arm that MEASURED THE ECCENTRICITY of the record and re centered the disc for play, it sells for big bucks if you can find one.

FINALLY, Your thoughts on the question?

regards, Ken Fritz
kftool
old_6eyes
46 posts
 
You could use an extra mat or mats to raise the record so that the spindle isn't in the way and center the record visually. This requires no modification of spindle or record. VTA will be off, of course, that's the part that makes it a less-than-perfect solution.

Removable spindles would be handy for this too, like the older Duals, etc.

I like the smaller spindle w/adapters idea.
kftool OP
104 posts
 
Dertonarm,

The center spindle was not omitted. The spindle dia. on the
Denon is .284 inches; the smallest diameter generally found on LPs. If i find a record with a larger hole I notice the back and forth motion of the arm. I then put the polycarbonate centering device back on the clamp ring and diddle it back and forth which re locates the LP on the smaller spindle. Putting the arm back on tells me if it's centered properly, or at least as best as my eye can tell. I believe most, if not all tables have a spindle dia of .284 inches, at least my two Sota tables have that same dia.

Ken
dertonarm
1,042 posts
 
Dear Kftool, those 0.284 inch do equal the 7 mm in metric world. That is indeed the standard.
Thank you for setting this straight.
jlin
57 posts
 
One thing to note is that there is nothing to prevent the eccentricity to be different on the two sides of the record. For example, the record may be perfectly centered on one side but off on the other, or it may be off on both sides but in different directions. Just a little extra thing to think of. :-)
Ag insider logo xs@2x
rauliruegas
13,103 posts
 
Dear Ken: The fix????

IMHO, like in the human been healthy, the name of the game is to prevent not to fix.

We have to form an audio-association ( audiophiles/music lovers ) and ask to the RIAA ( or to the correspondent oficial institution ) to make a RIAA standard for a " perfect center hole " to all the LP manufacturers, this is what in my opinion we have to do not trying to fix things that are errors on the audio item maker.

We have to be serious on this subject and many others and give it a serious treatment looking for a final solution. IMHO I think we need to help us in a more definitive way.

Do you want to start? any one? who say, I.

Regards and enjoy the music.
Raul.
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