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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
has2be's avatar
has2be
555 posts
 
Hi Ken.I know a Fello who back in the seventies started doing what many would think is crazy but since he never had plans on reselling any albums and like alot of us back then he bought two copies of favorite lps. He was quite the tweaker long before it was so popular. He actually made a jig that laid the album perfectly centered and protected from surface scatches. He then using a drill press with a very sharp forstner bit carfully cut out a perfect centered clean hole exactly the size of a 45 adapter he machined himself.When the album was placed on the platter with the adapter he sat the weighted clamp that he machined which had the center machined out to fit over the adapter. Yes it did cut out some of the label obviously but every record he played the arm tracked straight and steady with no eccentricity at all. Definately NOT recommending this just thought I would share this. Some thought he was crazy but I admired the fact he fixed the problem. Also he always reminded me that others think he was ruining the lps but he said "I just ruined everybody elses ability to borrow them".Cheers
kftool OP
104 posts
 
Has2be,

Whenever you think you're the craziest person on the planet, someone trumps you.

Thanks for the reply, Ken
dertonarm
1,042 posts
 
Dear Kftool, dear T_bone, the best possible way to solve the problem with the notorious LP eccentricity should be a pure mechanical one and - most important - should go without any alternation on the given LP itself (widen the spindle hole etc. etc.). I think the way to go is to decrease the spindle diameter and provide a kind of adapter (or a small 3-4 unit set with different ex-center adapters) which balances the LP-eccentricity. I have done so in my fist TT design back in the early 1990ies. It works fabulous and without any alternation or harm to the LP physics (sometimes you want to sell a LP....... a wide center hole does not really add to the value...) . The procedure itself is a matter of 30 - 50 seconds. Even LPs with eccentricity up to 3 mm (which is a lot...) when played with this adapter were dead quiet center in play. The modification should be done at the TT's spindle - not at the LP. The Naka's TX-1000 does cure one problem with an extreme amount of work and technical (electronic) periphery - and opens up a few boxes of other problems by doing so. A friend of mine just had a Nakamichi TX-1000 restored past week and put to work. More electronic than in any of our preamplifiers (which phono board....). But - it works. But so does the mechanical approach described here.
t_bone
1,182 posts
 
Dertonarm,
For simplicity's sake, I agree that a 'minimum spindle' plus off-center adapter should work fine. For the sake of the search for perfection (such as in the thread about drive systems), you'd need a lot of them and a way to measure. The one 'problem' with this is that not all of our TTs have removable/interchangeable spindles.
dertonarm
1,042 posts
 
Dear T_bone, you know I like to look at TT and tonearm questions from the physical and geometrical point of view first.
Well - even if you use say 30 adapters with a step of 0.1mm each in compensated eccentricity, it will still be a fairly easy, cost-effective and very precise solve to the problem. We have 2 fixed points here - the spindle hole in the LP and the spindle of the TT.
To compensate the given eccentricity we have 3 options:
a) compensate at the platter itself and leave spindle and center hole alone = Nakamichi's approach (the whole platter compensates the eccentricity of the LP...... I see it working and I do not have a sense of "good solution" - the sound isn't anything to write home about either...)
b) widen the center hole to compensate eccentricity at the problems core itself - the LP (= modification of teh LP's spindle hole making it hard if not impossible to play the LP on any other turntable.. and results in a huge decrease in value. Certainly not the way to go for a collector of highly priced vintage vinyl..).
c) decrease spindle diameter to compensate eccentricity at the spindle. Solving the problem again at the very core of the problem. Modification can be done to almost any TT.

What I can say is that the method I described works very good in everyday handling.
You make a note for any specific eccentric LP and have an adapter with the specific compensation at hand in a few seconds.

There is no free lunch here.
Honestly - I can not see any other option aside from the 3 mentioned above.Do you have any idea?
Anyone else?
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