Hi all,
is this a real problem?
looking to do a home build, and ran into this one. S.E. Grimm wrote a topic on this in his blog
according to the various standards, RIAA and IEC this can be between 0,05" (1,27mm) and 0,2 mm- assuming manufacturers would comply
I am looking at biglobe.ne.jp/~yosh/standards_table.htm
If so, being an issue, any remedies (apart from buying a Nak)😀
appreciate the help
thx
Coolerooney
is this a real problem?
looking to do a home build, and ran into this one. S.E. Grimm wrote a topic on this in his blog
according to the various standards, RIAA and IEC this can be between 0,05" (1,27mm) and 0,2 mm- assuming manufacturers would comply
I am looking at biglobe.ne.jp/~yosh/standards_table.htm
If so, being an issue, any remedies (apart from buying a Nak)😀
appreciate the help
thx
Coolerooney
In the 60s we called it character.
If it is a single, you can "dink" the larger hole slightly off centre or just place it on the table without a centre pin.
If it is a single, you can "dink" the larger hole slightly off centre or just place it on the table without a centre pin.
Character. But not very musical in the sense slowly varying pitch doesn't add to the general experience, at least not IMO.
It ought to be possible to devise a mechanism that can auto-centre a record, even if the hole is off-centre and the spindle is a tight fit. Over the years some attempts have been made.
From 1st principles, the spindle would need to be free to move in the plane of the record until spindle rotation had minimum net radius and minimum angular momentum, then it could be clamped. So one would put a record on the spindle, it would be off-centre, but would self-correct before clamping.
Something like that...………[edit: ah just realised that doesn't work either, doh!]
LD
It ought to be possible to devise a mechanism that can auto-centre a record, even if the hole is off-centre and the spindle is a tight fit. Over the years some attempts have been made.
From 1st principles, the spindle would need to be free to move in the plane of the record until spindle rotation had minimum net radius and minimum angular momentum, then it could be clamped. So one would put a record on the spindle, it would be off-centre, but would self-correct before clamping.
Something like that...………[edit: ah just realised that doesn't work either, doh!]
LD
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In my thousands of records, I had one with this problem. A Colombia masterwork, oddly enough, Buxtahude. I'm fairly sensitive to pitch, being an experienced double reed player. Couldn't play that one.
The Roksan Xerxes had removable spindle, so one could center the disc manually (although it was not its primary purpose).
I have a xerxes with said removable spindle. The problem is still finding an easy method of measuring the offset and adjusting it which doesn't suck all the fun out of spinning a record.
Yes, of course most of the time the offset is very tolerable from a listening point of view.
I just thought that there ought to be a mechanism way to self-centre. It seems so simple, but very elusive.
Some sensor would need to measure eccentricity. I suppose that could be tonearm position or a separate optical sensor. Producing an error signal used to correct spindle position and sliding the record over the platter to centre it.
I don't think that can be done purely mechanically, think that needs a servo.
Or, move the tonearm pivot to accommodate?
LD
I just thought that there ought to be a mechanism way to self-centre. It seems so simple, but very elusive.
Some sensor would need to measure eccentricity. I suppose that could be tonearm position or a separate optical sensor. Producing an error signal used to correct spindle position and sliding the record over the platter to centre it.
I don't think that can be done purely mechanically, think that needs a servo.
Or, move the tonearm pivot to accommodate?
LD
I found the new USB microscopes with decent mounts to work fine, focus on a spot on the cart and split the difference in wander with one complete rev while turning the table by hand. A couple of iterations and it is much better.
I did buy an 'integrated' USB scope and display for this purpose, but the mount is frankly rubbish so I need to build something better. There are some nice ones with decent stands, but then I need to plug a laptop in to play a record, which would annoy me.
SWMBO will be unhappy but I might splash £15 on a cheapy retort stand to try that.
SWMBO will be unhappy but I might splash £15 on a cheapy retort stand to try that.
Funny the one I bought seems to have disappeared, but there is a new one that comes with a little screen or talks to your phone. Mine has the stand shown and the simple metal tube camera. The base slips nicely under my TT, I imagine that might not be true on all tables.
Amazon.com : Aomekie USB Digital Microscope Magnifier Camera Video 200X Zoom 1600x1200 HD 2MP PCB Inspection Handheld Endoscope with 8 LED Lights and CMOS Sensor for Mac Windows PC Android Phone : Camera & Photo
That's the one I was considering as a next step. Hadn't realised it would work with a phone (if I had an android phone). The endoscope attachment is slightly worrying...
Hello Luckythedog,
The Nakamichi turntable does all of that, as has been mentioned in this thread.
One could simplify the Nakamichi by removing the "test arm" and mounting my own "pivoting tangentially tracking tone arm" on the Nakamichi. The independently floating head-shell of my tone arm would then output a fluctuating signal via the built-in Hall effect sensor which could be used to drive the XY spindle motors.
Sincerely,
Ralf
Been over this a number of times. It's not easy to make it go fast. You're shooting for under 1mm, under .5mm to match the Nakamichi. And it works... it sounds better.
You need something more precise than the hand to do this... tiny fine thread screws can be used, but as you may imagine when and where to set them presents another interesting challenge.
Essentially you need a platter on top of platter, with it's own spindle. Then you've got a question of what kind of surface to surface do the platters make because they need to move against each with small movements...
It gets more complicated from there. 🙂
You need something more precise than the hand to do this... tiny fine thread screws can be used, but as you may imagine when and where to set them presents another interesting challenge.
Essentially you need a platter on top of platter, with it's own spindle. Then you've got a question of what kind of surface to surface do the platters make because they need to move against each with small movements...
It gets more complicated from there. 🙂
With my roksan I can nudge the record as the mat is not grippy. But would need either a delicate touch or a micrometer to do this. With the microscope+built in display you could mark lines that show how much correction is needed and where to apply it (max excursion).
I suspect gentle tap would end up a lot quicker to do.
I suspect gentle tap would end up a lot quicker to do.
So how would that work Scott? Do you set the cart in a run-in groove, then manually rotate? Do you then see a wander, superimposed on the radial motion due to the run-in groove?
Jan
No, the run in is too widely spaced use a real groove near the beginning. It takes a little practice, rotate to either a max or min then rotate 1/2 a rev and move the LP along the spindle/needle axis to split the difference. The groove spacing will give a slight error you might be able to tweek out. When perfect the cart should move smoothly in as you rotate.
Of course you commit to enlarging the hole and reqiring alignment each time. A complete process would include some way of marking the best spot, maybe a thin disk with a precise hole and some double sticky tape?
Neat, JP. But unavailable. You'd still need a micro threaded thing to adjust the LP to be a really good tolerance.
Bill, if your LP can easily move then it probably doesn't sound as good as it could. Touching the LP while it spins would be better to stop the platter than have the LP move at all.
Bill, if your LP can easily move then it probably doesn't sound as good as it could. Touching the LP while it spins would be better to stop the platter than have the LP move at all.
Imho there are 4solutions:
a) Get a well calibrated Naka TX 1000 Turntable , compensating THIS issue
b) accept it like it is
c) throw the record in the garbage
d) get another record from the same musician and try your luck
a) Get a well calibrated Naka TX 1000 Turntable , compensating THIS issue
b) accept it like it is
c) throw the record in the garbage
d) get another record from the same musician and try your luck
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