The centering turntable was the Nakamichi Dragon CT. Link is below.
http://www.vinylengine.com/library/nakamichi/dragon-ct.shtml |
There was also the Nakamichi TX1000 (the CT's bigger brother I thought).
I believe it is more easily solved using a method like you describe, though that requires a 'virtual spindle' rather than a real one, and some kind of ranging apparatus. As you hint in your post, if physical and working off the outer edge of the disc as a reference, this only works if the stamping is done so that the outermost groove is equidistant (or actually, the 'appropriate distance' (because the appropriate distance should decrease linearly by the groove spacing over one revolution)) from the edge of the disc. If done based on the grooves (the ideal), that requires another ranging device measuring groove placement on the surface rather than either spindle or outer edge in order to set the records place on the mat. That sounds difficult.
On the face of it, the Nakamichi solution is actually somewhat elegant, because the timing and distance of the "swing" is perfectly regular and therefore easily programmable, and it is not very fast, so there is no 'hysteresis' involved in 'violent' direction changes (assuming overhang of zero - if overhang is not zero, it becomes a bit more complicated I think). If there were slits in the TT platter/mat which allowed laser ranging to the underside of the record with enough frequency, this could be set by the TT before the stylus touched the vinyl, otherwise it would have to be done based on the arm being mechanically sensitive to the swing.
I, for one, would be interested to see Dertonarm wade in... |
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 |
Has2be,
Whenever you think you're the craziest person on the planet, someone trumps you.
Thanks for the reply, Ken |
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. |
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. |
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? |
Dertonarm,
I am not positive I understand the way kftool's existing clamp system works, but if I do understand correctly, it effectively does away with the spindle completely (after all, as long as the record is centered with a peripheral guide and a heavy weight in the center, and there is enough friction between the record and the material beneath, one does not actually need a spindle... and that would be a 4th way.
Though I agree that a mechanical way is possible, and the small center spindle method is probably the easiest to implement if starting from ground zero... |
Dear T_bone, the system Kftool describes does provide pressure with the outer ring plus the center weight and further - by straddling the LP in its center - does provide something like a "material tension inherent pressure" by creating something like a "small convex bubble" at the center. This works great in providing high surface contact pressure over a very high percentage of the records surface. As the center weight is fairly heavy (approx. 3 lbs) there is enough down force provide without clamping to a spindle. Can't really tell from the description either whether the spindle was omitted.
Kftool - can you please clarify this point? |
Has2be, years ago (over 30), I bought a system, which included a rasp for making the spindle hole larger and adhesive rings much like those for sheets in a loose ring notebook. There was also a wooden base with a pointer. You used it to center the record and to widen the hole. Once centered, you slid the adhesive ring down the spindle to "permanently" center the record. You then flipped the record and put another ring on that side. It was a tedious process which I only did perhaps five times. Somewhere I have those records. |
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. |
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 |
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. |
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. :-) |
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. |
Hi Raul,
It's been a while since we crossed threads. I have a feeling that by now you have a few more tone arms and cartridges; Ain't it great! I'll send 50 bucks to kick it off if I can get a Happy meal coupon with my tax free donation.
regards, and" Enjoy the music." A friend once said that to me.
ken |
Dear all, that standard for the center hole was made in late 1940ies when the technical/mechanical standards for the microgroove longplaying record were set.
Those standards were precise numbers.
The problem is poor quality control, the ever increasing need for cutting production costs and too little care in the manufacturing process.
Companies like King Records / JVC Japan and several of the smaller dedicated record companies did always present LPs with very precise center holes. Today the LP-manufacturing is such a small segment of the audio/video market, that this (we...) and its (our..) needs are of no interest at all for the industry. |
Dear Jlin, you are right - very often the two sides do differ in their eccentricity. In that case the "alignment" has to be done for each side individual. |
Dear Dertonarm: Where we can find those standards on the subject?
Now, the " perfect center hole " standard when is achieved give all of us an immediate quality improvement, it does not matters which analog system we own.
is there a " road " for the recording industry can fulfil with that standard? who is the institution that have to control that that standard be fulfil/realize by the LP manufacturers? how anyone could " force/compel " to the LP manufacturers to do it?
We are paying a lot of money for new LP's that are really bad/wrong in its overall quality.
I don't know others but I'm willing to pay an extra " fee " for that " perfect center hole " standard, no doubt about: that makes a difference for the better.
We all here are commited to improve the quality perfomance in our home systems but I can see that for many of us that is not really a priority because in more than one ocasion I bring this subject with receive almost no " eco " to make and take actions about.
I consider you a serious man on this and other subjects why don't start ( you and me ) or take some actions about, let me know IMHO we need to do it like a " group ", this is not a " fight/war " for one person.
What do you think? or you think it will be " futile " ( like you say. )
+++++ " is such a small segment of the audio/video market, that this (we...) and its (our..) needs are of no interest at all for the industry. " +++++
well, remember that we ( the customers ) are part of the industry and not only that but that industry " lives " thank's to us not to them.
regards and enjoy the music.
Raul. |
Dear Raul, I agree. But the only part of the market we have SOME buying power is the specialised audiophile LP market. And even here - take the infamous Classic Records 200gr issues which were certainly plagued with pressing faults and warped samples - even with LPs which do ask some serious retail prices, we seldom get the excellent and careful pressing quality we ask for and deserve to get for our money.
I am collecting LPs since the early 1980ies.
There always were certain companies showing great care in what they released - excellent quality control. JVC Japan, King Records, for a long time DECCA and EMI (at least in their classical department...).
Today maybe we could put some "pressure" for quality on Classic Records, Speaker Corners etc.
You are right - we should try.
We all.
A small group is not enough.
We would need something (something like...) like the international boycott movement which eventually helped overcome apartheid in South Africa in the 1980ies/early 1990ies. That was a display of positive buyer's power (at least here in Europe).
I think the best way would be if Classic Records and all other audiophile record companies would just start having all their LPs pressed at JVC / Japan.
That would solve all our headaches.
I am in. |
Dear raul, I don't know whether the old Microgroove Longplaying Record standards can be found anywhere on the web (but I believe so). I have them in the old printed papers of AE Anthology and Wireless World. |
Dertonarm: Ok, good that you are of that kind of people that like " live its life " ( make things happen. ) and not only see how its life goes through.
Please email me to start about. All of you auio and music lovers friends ( elsewhere you are ) are invited too.
Regards and enjoy the music.
Raul. |
As a fact we need you all!!!
You are WELCOME! |
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. |
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. |
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. |
Dear Dertonarm: Very good, I already email you with some thoughts. Please email me to go on.
Regards and enjoy the music.
Raul. |
Ken, what are you using as an arm on the 308? |
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. |
