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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, 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?
t_bone
1,182 posts
 
Ken, another question for you about the 308 you are using... do you go through the line-amp directly out to amp? or did you unplug the arm outs from the board and run those to an equalizer? (And if so, have you tried the line amp and phono stages inside? Any thoughts??

My original question about the arm was asked because while it was optimized for the 103, it would be easy to imagine wanting to try a different long arm.

You mentioned in another thread that you didn't appreciate the MDF and top plate. Are you going to try and re-plinth the whole thing?

And by the way, if you want a pair of monitor headphones for the headphone monitor plug-ins on the left, they are the Elega DR-631C and they are still making them (be sure to get the 631C (not another letter) 10k ohm type with the #110 jacks - the 110-end type jacks cost about 5% more than the regular type but they are the ones for broadcast use). If interested, let me know and I can help navigate in Japanese for you.
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