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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
dertonarm
1,042 posts
 
Dear Raul, dear all, - I think the best way to start would be a foundation here on Audiogon. A kind of "Audiogon quality record collectors society" (...which is just meant as an analoghy - not my propolsal for a name for this group or society...).

It was Raul's idea and I believe Raul should start and name this.
However I think if we can relate this in any way to Audiogon it will be a much wider public and therefor much more (positive) power.
That way it would be more promissing - the chance to get really some influence on the LP-manufacturers and distributors.
Ag insider logo xs@2x
rauliruegas
13,103 posts
 
Dear friends: I already email Dertonarm on the subject to start about and we come back to you in a dedicated thread to share and take ideas from all of you.
In the mid-time you can email us with your thougths and ideas on the whole subject, I mean any subject.

Rgeards and enjoy the music.
Raul.
dertonarm
1,042 posts
 
Dear Raul, just briefly as these days are crowed with real world work for me.
As for the LP STANDARDS.
These are the points (certainly not all - but the ones which came to mind first) - in no particular order - which I believe should serve among others as standards for longplaying records:

- perfect centricity (i.e. - derivation less than 0.1 mm)
- virgin vinyl with high percentage of high purity soot to lower groove friction (this was done in the very early 1960ies for some special copies for reviewers and radio stations) - this minimizes groove noise.
- constant control of pressing temperature to avoid pressing bubbles.
- "non stress" cool-down process to avoid wraping of LP.
- all records packed in VRP or Mofi or similar "rice paper" soft poly inner sleeves and fixed to avoid movement during shipment.
- precise center hole
- flat outer edge (no "rim") of LP - like LONDON FFSS "pan cake" pressings.
- LP weight between 180 and 220 gram max.
- standard value for run-out groove - a certain figure like 3/4 inch or such.

Let me know your mind and your ideas please.
Ag insider logo xs@2x
rauliruegas
13,103 posts
 
Dear Dertonarm: Very good, I already email you with some thoughts. Please email me to go on.

Regards and enjoy the music.
Raul.
t_bone
1,182 posts
 
Ken, what are you using as an arm on the 308?
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