Do Off-center Holes Affect Sound?

the thin end of the wedge
TA

Re: Do Off-center Holes Affect Sound?

Post by TA » 15 Nov 2017 20:21

The 0.55 Hz would not bend the stylus much at all if the resonance frequency is around 10 Hz. With respect to warps, the speed variation is not at all as bad as off-center holes. Warp average frequencies are 2-6 Hz which means that a resonance of 10 Hz of arm/cartridge is just one octave above the warp frequencies.

Ideally I would like an at least 3 octave headroom to these disturbances. An horisontal resonance of 5 Hz and vertical resonance of 20-30 Hz would be fine.

billshurv
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Re: Do Off-center Holes Affect Sound?

Post by billshurv » 15 Nov 2017 21:43

Thanks, I'll take a look and see if I can find that online. I don't agree on the damping, but reading the full article might Help me understand where he is coming from.

jdjohn
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Re: Do Off-center Holes Affect Sound?

Post by jdjohn » 15 Nov 2017 21:57

jdjohn wrote:The February 1959 issue of Popular Mechanics has an article titled, "Hi-Fi Buyer's Guide: Tone Arms", which mentions this concept, and warps as well.
My apologies, it's actually Popular Science magazine from February 1959.

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Re: Do Off-center Holes Affect Sound?

Post by FloridaBoyDon » 16 Feb 2019 22:16

Off-center records was the primary reason I embraced CDs back when they came out—far more important to me than noise or other distortion.

As a teenager I was bugged by off-center records, particularly those containing sustained notes. Even on more harmonically or melodically complex music, the slight variation in pitch gave many recordings a “sour” quality. I never had the means to purchase one of those Nakamichi turntables, but I sure did understand the need!

My fix—then and now—was to widen the center hole and move it on the platter to correct the problem if it was bad enough; otherwise I’d just suffer through it. On several records I glued on a little centering guide so I wouldn’t have to do it more than once. THe guide was a piece of stiff (but thin) cardboard with a notch that I’d rest the spindle against when it was centered.

I imagine you could get sheets of self-stick vinyl circles and punch a 1/4 inch hole in the center of each one to use as a permanent fix—effectively moving the hole over to where it was supposed to be.

The same fix that worked on side one will most likely work on side two because the centering problem is generally due to sloppy drilling, not sloppy pressing. Not that it’s impossible to have side one and side two pressed off center to each other. It’s just that I’ve never needed a different fix for side two. And it stands to reason since both sides are presssed together using two pricey stampers held in close alignment.

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Re: Do Off-center Holes Affect Sound?

Post by ripblade » 16 Feb 2019 23:04

The stampers are individually punched before they're placed in the press. So yes, it is entirely possible that one side can be perfectly centered while the other is not.

33audio
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Re: Do Off-center Holes Affect Sound?

Post by 33audio » 17 Feb 2019 08:52

Hi Folks:

The maximum allowed runout for the LP is .050 inch, which is a lot of WOW.

It often exceeds this limit. This figure of .050 is from the 78 era.

Why didn't they tighten the tolerance? Probably because the stampers are centered by eyesight by tired pressing personnel. Thus, one side can be perfect and the other way off center, far more than .050 inch.

Yes, it makes a big difference in the sound even if you think you don't hear it.

I found that records from collections that were in comparatively good condition were those with a lot of runout.

I use a piece of solder wound around the head of a small plastic bottle as a guage to find the high spot. Put the solder wire (bent downward) next to the tonearm headshell lift. Then put a marker on the label to show the postion. I use a dice. Put a pencil mark next to the spindle as accurately as possible.

The main reason I use a direct drive turntable is because it can be slowly rotated by hand with the motor off.

This is a very critical procedure. Use a rat tale file (round small about 1/4 inch I.D.) to enlarge the hole enough to move the record over against the spindle. It is very easy to mess it up because a little error in the initial position of the dice will lead to a large cutting error in the hole. Make sure that you start moving the file in the center of the pencil mark on the record. Go slowly.

I have been doing this for over 25 years and still mess them up sometimes. Let a layer of fingernail polish dry in the over cut area and then use a small pocket knife to take out enough polish to get the right position.

Sometimes both sides are out and fixing one side makes the other side worse. There is a way around this with the fingernail polish procedure.

The bad side of this is that it ruins the resale value.

If done properly (and you have a well fixed regulation diameter spindle) just move the record over to where the pencil mark (supposedly in the right place) is and play the record. It is a pleasure to have them run on speed.

Also, the center hole may simply be too large. In this case find the place where the record runs concentric and put a pencil mark on the lable.

Hope this helps you out with this issue. Regards, Mark

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Re: Do Off-center Holes Affect Sound?

Post by Ghaasl » 17 Feb 2019 14:45

I have a reissue copy of Pet Sounds that’s got an off center spindle hole. It’s bad enough that the album is unlistenable. I either have to enlarge the hole or get a new copy. Shame because it’s one of my favorite albums.

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Re: Do Off-center Holes Affect Sound?

Post by lini » 17 Feb 2019 16:19

33a: Actually most other LP standards (DIN, IEC & JIS) only allow for a much lower maximum groove spiral to centre hole excentricity of 0.2 mm (BS even 0.13 mm only) - while an RIAA bulletin contains a note, that explains, that those 0.05 " (ca. 1.27 mm) rather aren't meant as quality parameter in terms of wow, but as limit to prevent certain types of auto-stop (& -lift & -return) mechanisms from being unintendedly activated, so that the RIAA limit isn't really comparable to the limits of the the other standards.

Greetings from Munich!

Manfred / lini

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Re: Do Off-center Holes Affect Sound?

Post by 33audio » 18 Feb 2019 02:30

The standard for the trip mechanism sounds familiar.

I have had a few records far beyond .050 inch.

Pressing records is a very physical process. I'm sure the workers
got very tired at some point.