Do 45 RPM records need higher anti-skate setting?

Atmasphere,
It would seem so.

Lewm,
I think your take on it is right. All I would say is that rather than "headshell" offset angle, it is perhaps better to think of it as "groove" offset angle (which is what gives rise to the tracking angle error, as both the cartridge offset and headshell offsets remain constant while the groove offset angle changes, the error increasing markedly at the innermost radii, giving rise to higher skating forces there).
J
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Zavato,

Just noticed this.
Your mistracking is most likely caused by the 45 presenting the cartridge with the problem of tracking a groove which makes the stylus accelerate at a greater rate. This puts it at the edge of its tracking envelope, therefore the influence of the skating force (which is always present in a pivoted arm) more apparent, resulting in distortion on one channel.

Normally, with insufficient anti-skate, the VTF is enough to cope with most groove modulation. When there is more energy in the system, that is not the case and shows up the imbalance in downforce on each face of the groove, which anti-skate is designed to compensate.

Omsed,
you said

when you think you know it all start looking for your mistakes!

Have a look a R.J Gilson's paper in Wireless World Oct 1981 for some more reasons why you might wish to increase antiskate disproportionately as the arm approaches the inner grooves. Also, watch you don't fall into the trap of regarding anti-skate as a setting governed by a "I can't hear a difference with anti-skate, so why bother using it" attitude.

As an aside, regarding 45rpm records, if we had been talking about 7" singles rather than 12" LPs, that is another thing altogether. (see my blog
for more on this and on anti-skate generally.)

Omsed,
You need to read and assimilate before spouting. Otherwise you may be
considered a wanker.
[quote] This greater acceleration does not exist. And more energy is NOT
being put into the system or the volume would be louder on a 45![/quote]

So would you care to enlighten us otherwise why anyone would use 45 rather
than 33 1/3 other than to be able to have a disc with higher modulation?
As far as my (possibly inferior) knowledge is aware, that a body revolving
faster has more energy than one revolving slower. I thought this was
something to do with kinetic energy?
Therefore permitting higher signal levels to the cartridge.
Of course you may not have noticed any difference between 45s and 33s, in
which case get yourself some and listen....

Re centipetal force - think about it. The only revolving item other than the
platter, is the tonearm, which is the item under discussion, and there are
minimal, and irrelevant, centripetal forces acting on it, which is what I have
said in the blog.
John

Lewm,
If there was no groove, the arm would skate and rotate until there were no forces acting to make it do so, so there would be, for a short while, a "conventional" centripetal force acting on the stylus and arm along the stylus to pivot axis caused by the rotation.

When there is a groove, the inside face restrains the stylus, so there is effectively no such force, because the arm is rotating only minimally (at less than 0.01 rpm), and the stylus has such a tiny mass, that any forces are negligible, and totally overwhelmed by the friction forces by many orders of magnitude.
J

Mmakshak,
There is actually a logical default position: namely, that given there is a skating force (which is old, proven, science, well documented, though commonly misunderstood) and which leads to VTF being different on each channel, it should be counteracted.

it is approximately between a fifth and a third of the VTF, depending on stylus profile and other factors.

Now, while it may vary subtly to some debatable extent across the record and with platter rpm, it is, as Omsed stated, always there and always towards the centre. Applying anti-skate may or may not be audible, but it is designed to compensate for something which could result in record or stylus damage, which is why 99.9% of arms have it in some form.

Users seldom use VTF below cartridge makers recommendations, because the cartridge will mistrack and even if you can't hear that mistracking it is acknowledged as being a bad thing.

However, without anti-skate, the chances are that your cartridge is running below recommended VTF on the right channel.

John

Timeltel
you said:

A pivoted arm with overhang will seek the center of a blank (ungroved) LP. Would it not move towards the spindle more rapidly if the disc were spun at 78 or 45 rpm than at 33.3?

That depends on the friction generated. All things equal, the friction would be more or less the same, as once the stylus is moving the friction (dynamic as opposed to static) is constant if nothing changes. It is is like when you try to push a heavy box. Static friction makes it hard to get started, but once it is moving it takes more or less the same effort whether it is moving slowly or quickly ). And it is the friction which supplies the force to rotate the arm.

However in any particular modulated groove, the friction changes with velocity (due to the modulation). So in the case of the OP, there may have been a particularly loud passage which indicated that the the existing anti-skate setting was inadequate.

John

Omsed,
No one is talking about spinning a complete turntable, or that there is a centripetal force involved in the skating issue, or that the cartridge is spinning with the record. If you read all the posts here and elsewhere I think that is clear. The only reason for using the term at all is in attempting to try and clarify the difference between a force acting toward the centre in the context of an arm being spun or a body in orbit, and a force acting towards the centre in a tonearm in reaction to the friction in the groove.

VTF is, of course, different on each groove face unless anti-skate is used. That's why the skating force is a problem. That is elementary. I don't get what you are saying re the groove faces being identical etc. We are not talking about record cutting, but playback.

Regarding information storage, if I store the same information in a bigger space, that's all I have done. When I retrieve it, I get it back. The point about the bigger space is that I can store more information, otherwise what's the point? Perhaps I am wrong, not being a recording engineer, but I was under the impression that higher speed allowed higher levels, whether it be tape or vinyl. And if there is more information, of whatever kind, the cartridge has to do more work to retrieve it, hence the reference, albeit imprecise, to energy (I take your point about the irrelevance of the platter's kinetic energy).

As you are having difficulty finding proper scientific papers, I've posted a link here. Look at Gilson and Alexandrovitch.

John
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Timeltel,
As Omsed said

Skating force remains the same since it is based solely on the magnitude of friction and the offset angle of the tonearm. Same tonearm, same friction, same skating force, so anti-skate should remain the same.

However, if the friction force changes then so does the skating force, so it depends on whether the coefficient of friction remains constant, which is an assumption.

For an ungrooved as opposed to grooved disc, I don't know. For what it's worth, my experience of records skating (mainly in days long gone by) is that I recall them skating at much the same speed whether 33, 45 or 78, judging by the pitch of the scratching sound...

John
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Atmasphere, Tonywinsc,
I used to think, as a previous poster, Omsed, posted, that antiskate should be the same irrespective of speed because dynamic friction would apply.
But over the years I have continued to be open to new information I previously wasn't aware of, and willing to modify my ideas if the facts didn't fit them. (Wish that were the case with many scientists).

The OP said all was well with his deck until he played this particular record, and that the problem was solved with an increase in anti skate. If that was the case, then the problem was not with the record, but too little antiskate.

This might fly in the face of conventional engineering opinion, but only if the facts are ignored. The logical answer is that there was more friction, therefore more skating force. And the reason for that would be, as you noted in your example, Tonywinsc, increased modulation, as per studies by George Alexandrovitch, (JAES, 1961). His study showed that on an unmodulated groove, friction remained constant with groove speed, increasing only with downforce. On a modulated groove, friction increased for the same downforce, and also with decreasing radius.

There has been a lot of good, reliable, proven, information on skating forces available for many, many years, which is why virtually every arm was, and is, supplied with antiskate.

John
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Lewm,
Check out the link to Alexandrovitch and other papers via this link.

He found that with an unmodulated groove, there was no change in friction with radius ie groove speed. With a modulated groove there was an increase in friction, and this increase increased towards the centre, despite, apparently, the reduction in groove speed.

Ct0517,
I don't get the thing in the ET manual regarding the two skating forces. Certainly there is a tiny component of skating force due to the stylus contact point and the cantilever bearing point being in different places, but as far as I am aware that is not a major consideration in terms of the overall picture. But all skating depends on overhang, because it is that which gives rise to the fact that the groove and arm pivot are not in a straight line, thus causing the forces, unlike in the ET which is a linear tracker. If it was set with overhang it would skate too.

John