I can stoop lower than that if I spend 5 minutes looking through the 'too bad to junk yet' shelf. Someone who gifted me a collection loved manotovani!
You Fiend! I'll have to go some to top that, and if I do I certainly won't be bothered about eccentricity 🙂
An externally hosted image should be here but it was not working when we last tested it.
The drawing of the adjustable spindle (image above) shows some dimensions so I can calculate the physical bandwidth. A rotation of 180 degrees will move the “zero point” about 47 mm (half the circumference). When the maximal correction of the eccentricity is 0,5 mm, turning the outer ring 1 mm will result into a correction of the eccentricity by nearly 0,01 mm. Because the diameter of the graduated scale is a bit wider, the visual ratio – to adjust the new spindle – is about 1,7 mm for 0,01 mm.
An externally hosted image should be here but it was not working when we last tested it.
The diagram above shows the relation between the correction and the “minutes” of the graduated scale. So when we set the pointer of the outer ring to 1 “minute” – from 0 to 1 – the correction is 0,017 mm. With other words, we can decrease the eccentricity of a record to a minimum of 0,017 mm.
This accuracy will result into an average deviation of a test frequency of 440 Hz that’s 0,11 Hz. So it is impossible to detect any fluctuation of the frequency – caused by the eccentricity of a record – by ear (see post #133).
An externally hosted image should be here but it was not working when we last tested it.
I can simulate this result into the “Feickert diagram” of the Nakamichi self centring turntable (post #22). The test frequency is 3150 Hz and the average deviation by eccentricity – when we use this new adjustable spindle – is now 0,8 Hz. I have copied the green line from the left diagram – the deviation of the turntable speed – to show this parameter will carry much weight with the amplitudes of the yellow frequencies, when there is a real measurement.
Only the tolerance between the new record hole and the outside of the adjustable spindle is critical. But I cannot draw any conclusions before I have made some new centre holes with the ordered milling cutter.
Are you sure turning down the spindle isn't a better idea. This will completely destroy the second hand value of any of your records. Fine if you expect to be buried with them, but otherwise not possibly optimal.
@billshurv,
I thought I never made a suggestion about centring records “on the fly” by removing the spindle of the platter. Because a record weights about 150 – 180 gram, so it is nearly impossible to push the record 0,1 mm horizontal by hand. Just because of the friction by gravity. Of course, there are tricks. Nevertheless, it is not sensible to centre records without a new adjustable spindle.
A spindle with a radius of 3,13 mm isn’t suitable for correcting the eccentricity of a record. Just because the insufficient length of half the circumference. That’s why we need a “big” spindle: lengthen the size of half the circumference is magnifying the scale to adjust a very small correction. So when we play a certain record day after day, every time we put the record on the platter after setting the adjustable spindle, the record will have the same eccentricity/centricity. The scale to adjust has only little tolerance.
Because of your last post I understand you have a lot of classical recordings. So most of your LP’s will have an eccentricity between 0,1 and 0,3 mm. Just because the vinyl records of classical music were made with more accuracy (so they were more expensive too). When you try to measure/observe the eccentricity of your classical records by a laserpen upon your “every day” tonearm, the result will show more eccentricity than when you use a “special” tonearm. An old one with an old cartridge with a rigid stylus and cantilever (fixated by glue). Just like that nice small arm of the Nakamichi turntable to detect the eccentricity: everything rigid.
Is it sensible to centre vinyl records? Well, it is a must for everyone who have spend more than 1000 euro for a turntable, tonearm and cartridge. Just because a nice CD player costs about 1000 euro. That’s quite simple.
A lot of people like it to start a small firm/shop. They have internet so when there is an opportunity (an idea that’s not everywhere around) they like it to get into business. So don’t bother about making new centre holes. When everything is working fine and published at the internet, it is only a matter of time and you can bring your records to a shop that will “drill” new centre holes. And you can buy in this shop a nice very accurate adjustable spindle too (and a laser arm). So if you once want to sell your old classical records, people will ask you: “What kind of centre hole do it have? Oh no, not a small one...”
(I am searching the internet for readymade 45 adapters because I probably can use them partly. To make the outer ring or perhaps the inner ring. There are a lot of sites that offer all kinds of 45 adaptors. Just amazing.)
I thought I never made a suggestion about centring records “on the fly” by removing the spindle of the platter. Because a record weights about 150 – 180 gram, so it is nearly impossible to push the record 0,1 mm horizontal by hand. Just because of the friction by gravity. Of course, there are tricks. Nevertheless, it is not sensible to centre records without a new adjustable spindle.
A spindle with a radius of 3,13 mm isn’t suitable for correcting the eccentricity of a record. Just because the insufficient length of half the circumference. That’s why we need a “big” spindle: lengthen the size of half the circumference is magnifying the scale to adjust a very small correction. So when we play a certain record day after day, every time we put the record on the platter after setting the adjustable spindle, the record will have the same eccentricity/centricity. The scale to adjust has only little tolerance.
Because of your last post I understand you have a lot of classical recordings. So most of your LP’s will have an eccentricity between 0,1 and 0,3 mm. Just because the vinyl records of classical music were made with more accuracy (so they were more expensive too). When you try to measure/observe the eccentricity of your classical records by a laserpen upon your “every day” tonearm, the result will show more eccentricity than when you use a “special” tonearm. An old one with an old cartridge with a rigid stylus and cantilever (fixated by glue). Just like that nice small arm of the Nakamichi turntable to detect the eccentricity: everything rigid.
Is it sensible to centre vinyl records? Well, it is a must for everyone who have spend more than 1000 euro for a turntable, tonearm and cartridge. Just because a nice CD player costs about 1000 euro. That’s quite simple.
A lot of people like it to start a small firm/shop. They have internet so when there is an opportunity (an idea that’s not everywhere around) they like it to get into business. So don’t bother about making new centre holes. When everything is working fine and published at the internet, it is only a matter of time and you can bring your records to a shop that will “drill” new centre holes. And you can buy in this shop a nice very accurate adjustable spindle too (and a laser arm). So if you once want to sell your old classical records, people will ask you: “What kind of centre hole do it have? Oh no, not a small one...”
(I am searching the internet for readymade 45 adapters because I probably can use them partly. To make the outer ring or perhaps the inner ring. There are a lot of sites that offer all kinds of 45 adaptors. Just amazing.)
I am astounded you want to effectively wreck good records without fully exploring other options. That is all. If I ever get to the point I can hear the eccentricity then I will look more closely at accurate corrections, but for now the only record I can think of with significant wow is a 1950s DG mono which is probably a recording issue rather than anything else.
I may have cloth ears, who knows.
I may have cloth ears, who knows.
If you drill a hole in an LP it effectively drops in value to almost nothing. If I have a record I paid 10p for I don't mind, but some in my collection are apparantly worth £80-£100. I would not consider putting a hole in those, especially when there are other options for correcting eccentricity.
This seems like an ideal topic for a double blind listening study. It would be easy to take multiple copies of the same LP and impose different levels of eccentricity on them by filling in and re-drilling the center holes. Setup multiple identical TT/arm/cart/headamp combos to allow switching between them on the fly. Establish the minimum eccentricity level that is detectable on music by listeners and survey the eccentricity of a broad cross section of LPs. If it turns out that a substantial percentage of LPs display audible eccentricity atrifacts then it is worth developing a potentially complex system to deal with these. If OTOH this is a problem at the end of the long tail of the distribution of LPs then it becomes another factor adding to the category of poorly produced LPs that don't deserve a spin on a high quality system.
well in looking for a low tech and cost option in case I ever find this to be a problem I realised that, with a set of feeler gauges and a bit of grinding to get them to a point I should be able to easily adjust to under 0.1mm, in theory down to 0.01mm, but I doubt my hand is that steady.
@kevin: I can introduce up to 1.45mm of eccentricity at will by pulling the removable spindle out. I should try that.
@kevin: I can introduce up to 1.45mm of eccentricity at will by pulling the removable spindle out. I should try that.
This is the last “improvement”. It eliminates the tolerance between the new adjustable adapter and the 1,5 inch record hole (12 inch records). The polycarbonate adaptor (grey) looks like a perfect circle, but it isn’t. The “shoes” are 0,2 mm wider, so there will be an excellent contact between record hole and adjustable spindle (65% contact area).
Anyway, it is not easy to make this small adaptor without a lathe for metallic materials. So it is wise to make a first one out of synthetic material. I will give it a try.
An externally hosted image should be here but it was not working when we last tested it.
Anyway, it is not easy to make this small adaptor without a lathe for metallic materials. So it is wise to make a first one out of synthetic material. I will give it a try.
why does there have to be 'excellent contact'? that will just make it harder to remove the adaptor each time.
Well Tom I give you that, you're persistent if anything.
I probably would try something else, but that's OK.
Be curious how your solution works out, and how you are going to test it.
'I trust my ears' yeah right 😎
Jan
Attached are two papers with the necessary equations.🙂
Scott you mean by enormous damping of the arm /cartridge resonance?
The wooden tone arm designed for the FM cartridge?
Tom, the tonearm/cartridge resonance is adequately excited by the much lower f excitation frequencies produced by the TT mechanism and the record wrap/eccentricity.
George
@billshurv,
That's a nice question. The aim is to prevent some tolerance between the spindle of the platter, both non-concentric rings and the new centre hole of the record. A tolerance of 0,017 mm isn't possible when there is some instability between the parts.
When I increase the contact area, the friction/wear will decrease. Adaptors like the blue one above have 3 small contact areas. So I have to force the "hoofs" a bit into the record hole. Otherwise these small contact areas has to few "grip".
A small contact area will result in more wear locally. So I don't want tolerance and I don't want (too much) wear.
That's a nice question. The aim is to prevent some tolerance between the spindle of the platter, both non-concentric rings and the new centre hole of the record. A tolerance of 0,017 mm isn't possible when there is some instability between the parts.
An externally hosted image should be here but it was not working when we last tested it.
When I increase the contact area, the friction/wear will decrease. Adaptors like the blue one above have 3 small contact areas. So I have to force the "hoofs" a bit into the record hole. Otherwise these small contact areas has to few "grip".
A small contact area will result in more wear locally. So I don't want tolerance and I don't want (too much) wear.
Tolerance I understand, grip I don't. There is no need for the adaptor to grip the record. Records are not turned by the spindle, that is the job of the platter and mat, unless you are a follower of Ed Meitner. All the adaptor has to do is position the LP, after which you could remove it.
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