Could someone point me to a resource for the industry standards and tolerances for LP's? Such as label height, lead out groove diameter ect.
Thanx,
Casey
Thanx,
Casey
Hi,
There is an IEC recommendation, Publication 98, 1964 and its supplements, for this matter, but you have to buy it from the IEC web site.
Ghianni.
There is an IEC recommendation, Publication 98, 1964 and its supplements, for this matter, but you have to buy it from the IEC web site.
Ghianni.
I found this page linked from the one Werner suggested...
http://www.mcc.spacetown.ne.jp/~yosh/standards_table.htm
.... it covers everything I was looking for except the specification of label height. Does anybody know how far the label area is raised above the rest of the album, and what the tolerance is ?
I am looking at creating a depression in my TT platter to clear the label but I need to know how deep.
Ghianni...I would consider purchasing from IEC, but I haven't been able to find any pricing.
Casey
http://www.mcc.spacetown.ne.jp/~yosh/standards_table.htm
.... it covers everything I was looking for except the specification of label height. Does anybody know how far the label area is raised above the rest of the album, and what the tolerance is ?
I am looking at creating a depression in my TT platter to clear the label but I need to know how deep.
Ghianni...I would consider purchasing from IEC, but I haven't been able to find any pricing.
Casey
One thing that specification didn't mention is that some LPs are flat(ish) and some have a 1 degree angle to them. Have a look and you will see that some have a distinct dip at the run-in groove, followed by the 1 degree slope up to the final groove, whereas others are flat. I have a vague recollection that this "innovation" may have been started by RCA (probably to save vinyl during the 1973 oil crisis).
Lovely 😡
It would seem to make sense then to "bowl" the platter by 1 deg. to ensure a solid coupling to the platter..I think the "flatish" records could stand being deformed this small amount with the record clamp.
Thoughts ?
Casey
I knew you'd be pleased. Dishing the platter by 1 degree and applying a clamp sounds sensible. You'll need to measure a couple of LPs to see where the 1 degree dish should start from, and put a rather steeper opposite dish before that to ensure that you don't end up supporting the LP by its periphery.
The other alternative is a reflex clamp, similar to what VPI has done. It works surprisingly well.
This looks like it could turn into a real can of worms...I don't have many albums on hand (yet) to measure. Was this an exclusive RCA "innovation", or did the rest of the industry follow suit ?
Well I'm all for a simpler solution. But as I picture this in my mind ( such as it is), I see the clamp holding the thicker portion of the record down while the thinner section "floats" above the platter.
What am I missing ?
Casey
You're missing the reflex action. Under the center spindle (which is threaded), the record rests on a washer (roughly 25mm dia), which makes it float a bit above the platter. An inverted cup, slightly smaller than the label, is placed over the spindle, then a knob is threaded on. This presses the cup against the record, deforming it a bit to snug up against the platter.
Got it... Anybody happen to know how much of a curve ?
If anybody happens to own one, as well as a dial caliper, you could measure the diameter and the depth of the center. The arc could then be calculated. I think this info would be very useful..oh ya, the thickness of the rubber washer would be nice also.
Just sayin' 😀
If I remember, I'll buy a couple of awful LPs in a charity shop at the weekend, run them through the bandsaw, and check the angle across the recorded track.
Just an aside...
IIRC, the raised lead in groove and label were meant to protect the grooves when one stacked their records on a changer. (which is also why some classical box sets have the discs numbered the way they do - one could place the entire set on their changer and play through without having to flip each record.
Cody
IIRC, the raised lead in groove and label were meant to protect the grooves when one stacked their records on a changer. (which is also why some classical box sets have the discs numbered the way they do - one could place the entire set on their changer and play through without having to flip each record.
Cody
OK, on my table (a VPI HW19III), there is a milled out recess in the platter in the label area, 4 inches diameter, 0.020" deep. The washer that fits over the spindle is rubber, I'd guess about 65 Shore A, 1.25" outside diameter, 0.0625" thick. The clamp cup is 3.375"OD, with the cup's side wall being 0.125" thick.
Sy, I shall hence forth speak highly of you in all future social engagements 😀 ...
... I gather from this description, that the bottom of the clamp has a hollow machined out. The point I'm not completely clear on is what you refer to as "thick". Do you mean the depth of the hollow, or the width of the ridge around the periphery?
Thank you for the effort 😉
Casey
... I gather from this description, that the bottom of the clamp has a hollow machined out. The point I'm not completely clear on is what you refer to as "thick". Do you mean the depth of the hollow, or the width of the ridge around the periphery?
Thank you for the effort 😉
Casey
Okey-Dokey....Thank you. The more I think about it, the more I like this approach.
I'll just show them your new avatar..they'll figure it out.
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