Anti Skate Take 2

Re: Anti Skate Take 2

Postby Golear » Wed Sep 02, 2020 10:41 am

Rampelmann's article:
http://brujic.gradjevinans.net/HiFi/ve_skating_force_and_antiskating.pdf

(It doesn't have an author block immediately after the title. But the last entry, at the very end reads "Klaus Rampelmann" and I guess is a sign off. It covers the same stuff as the summary I read before.)

There's a fantastic Annex which describes anti-skate mechanisms on different arms.

In the paper, there's another gem, also new for me: "Skating force compensation is provided at the arm pivot. This means that a torque is applied at the pivot which results in a compensating force that is at right angles to the effective length." Yes... so? Well, if one looks at the accompanying diagram, one can see that the anti-skate force is not applied in the exact opposite direction as the skate force.....

Thanks.

EDIT: I removed a ref to a thread in the Steve Hoffman forum. That's how I found the Rampelmann article. But that discussion is not very helpful.
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Re: Anti Skate Take 2

Postby theeng » Wed Sep 02, 2020 3:34 pm

@Golear,

If you go back in this post and take a careful look at the spreadsheet photo of the VPI a/s device and read the calculations you will see the following:

1st - it calculates the total torque (Ta/s) the device develops - and there are 3 individual torque components - T1 + T2 + T3.

2nd - it then calculates the force (F1) that is applied to the thread based on its position (mechanical advantage) on the upper pole.

3rd - it then calculates the force (F2) that is applied perpendicular to the tonearm noting that the thread is on a angle at the collar that is located behind the pivot. Part of F2 is lost to pulling the tonearm axially toward the pivot that should have no measurable meaning.

4th - it then calculates the anti-skate force (Fa/s) that is actually applied at the headshell and this considers the tonearm effective length - but that force is mostly perpendicular. If this is repetitive disregard - I measured VTF with and w/o the a/s device and there is was no change in measurable VTF to 0.01 gm.

Stay well,

Neil

PS/If you have not already - you should download the two Audio magazines 1967-10 & 1967-11 and read the whole Kogen article, you may see where there may be some misinterpretation, but I am not getting into any discussion - its for your own edification. You can find these magazines here https://worldradiohistory.com/index.htm; you will need to do some searching at the header to find where those magazine are - I am working with tablet right now - its too cumbersome for me to give details. Given your technical interest you owe to yourself to be familiar with that site because of the enormous amount of data/info available. I have not yet found a way to be able to search the audio magazines - it mostly searches the technical journals.
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Re: Anti Skate Take 2

Postby Golear » Wed Sep 02, 2020 11:43 pm

I set the anti-skate according to the SoundSmith method. And as I've written in other posts, I have adjusted from there for specific LPs. So in my set-up, it's a very relative thing and I go by ear. I was very curious about the three videos by WAM. But it was just that. And as I noted in the original thread, I'm good.

I'm sure we'll all look at the link. Many thanks. I'm still curious about what you see might be wrong with Agostos' and Rampelmann's articles. But this is not a big request.

Cheers.
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Re: Anti Skate Take 2

Postby Jprod » Tue Sep 15, 2020 3:24 pm

Golear wrote:I set the anti-skate according to the SoundSmith method. And as I've written in other posts, I have adjusted from there for specific LPs. So in my set-up, it's a very relative thing and I go by ear. I was very curious about the three videos by WAM. But it was just that. And as I noted in the original thread, I'm good.

I'm sure we'll all look at the link. Many thanks. I'm still curious about what you see might be wrong with Agostos' and Rampelmann's articles. But this is not a big request.

Cheers.

I have read his method and quoted it here
“When you have it adjusted right, the arm will track slowly inwards on the SURFACE of a record (not in a groove) at the end of the record on the un-pressed flat space where the run-out groove is. Again, when adjusted correctly, it should track SLOWLY INWARDS toward the center at a MUCH SLOWER RATE than IF IT WERE ACTUALLY in the end groove.”

I for one have no idea what he’s talking about. When the stylus enters the end of a record it goes into the groove.
I have read it 5 times and still don’t understand. If someone can shed some light it would be appreciated
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Re: Anti Skate Take 2

Postby BuddyO » Tue Sep 15, 2020 3:44 pm

Jprod wrote:
Golear wrote:I set the anti-skate according to the SoundSmith method. And as I've written in other posts, I have adjusted from there for specific LPs. So in my set-up, it's a very relative thing and I go by ear. I was very curious about the three videos by WAM. But it was just that. And as I noted in the original thread, I'm good.

I'm sure we'll all look at the link. Many thanks. I'm still curious about what you see might be wrong with Agostos' and Rampelmann's articles. But this is not a big request.

Cheers.

I have read his method and quoted it here
“When you have it adjusted right, the arm will track slowly inwards on the SURFACE of a record (not in a groove) at the end of the record on the un-pressed flat space where the run-out groove is. Again, when adjusted correctly, it should track SLOWLY INWARDS toward the center at a MUCH SLOWER RATE than IF IT WERE ACTUALLY in the end groove.”

I for one have no idea what he’s talking about. When the stylus enters the end of a record it goes into the groove.
I have read it 5 times and still don’t understand. If someone can shed some light it would be appreciated


My interpretation is that he is trying to say that rate of travel for a properly adjusted antiskate setting (if on a groove-less surface) should be much slower than the rate at which the arm travels when it is in the run-out groove.
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Re: Anti Skate Take 2

Postby Jprod » Tue Sep 15, 2020 4:04 pm

So use a record with a blank side and see if it’s slower than on a run out groove ?
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Re: Anti Skate Take 2

Postby theeng » Tue Sep 15, 2020 4:30 pm

Jprod,

What Soundsmith is talking about is the blank space between the run-out groove. It takes some patience - and a number of tries - but you are trying to drop the stylus/tonearm in the blank space between the run-out groove and see that the stylus tracks slowly inward until engaging with the run-out groove. The whole event is just a few seconds. HOWEVER, if there is very little anti-skate initially set - the stylus can track inward so fast that it skips the run-out groove and can crash into the label unless you have an auto tonearm lift device installed - personal experience - my Little Fwend caught my 12-3D tonearm and lifted it.

Soundsmith as does many address to first view the cantilever in its relaxed position (above the record) and then check it when in the groove playing the record and verify that the cantilever is not angled left or right (from the cartridge body) when viewed from above or from the front (cartridge design dictates - Soundsmith can be viewed from front and above). If its angled adjust anti-skate to correct. You can then try the Soundsmith method or you just use your ears.

Hope this helps
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Re: Anti Skate Take 2

Postby Jprod » Tue Sep 15, 2020 5:09 pm

theeng wrote:Jprod,

What Soundsmith is talking about is the blank space between the run-out groove. It takes some patience - and a number of tries - but you are trying to drop the stylus/tonearm in the blank space between the run-out groove and see that the stylus tracks slowly inward until engaging with the run-out groove. The whole event is just a few seconds. HOWEVER, if there is very little anti-skate initially set - the stylus can track inward so fast that it skips the run-out groove and can crash into the label unless you have an auto tonearm lift device installed - personal experience - my Little Fwend caught my 12-3D tonearm and lifted it.

Soundsmith as does many address to first view the cantilever in its relaxed position (above the record) and then check it when in the groove playing the record and verify that the cantilever is not angled left or right (from the cartridge body) when viewed from above or from the front (cartridge design dictates - Soundsmith can be viewed from front and above). If its angled adjust anti-skate to correct. You can then try the Soundsmith method or you just use your ears.

Thanks. I will try to find an lp that has a longer run out groove area and try it tonight. As it is my cart travels very slowly in the run out groove. It’s a Ortofon 2m black and I went without anti skate for a while and now trying with.

Hope this helps
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Re: Anti Skate Take 2

Postby Peer Gynt » Tue Sep 15, 2020 10:50 pm

Soundsmith’s strategy is designed to get a little anti-skate, but not a lot.

He is probably right that we don’t need as much as will be dialed in with a traditional test record.

But he looks at it from the perspective of a retipper. He knows that the tip wears more on one side if bias is too high.

But if you use bias to maximize your sound quality, you will set it by ear and accept the wear that may or may not come as a consequence.

Flat grooveless vinyl does not load the arm like grooved vinyl. And anyone who argues that you can set bias perfectly for one record and that that setting will be perfect for another record is whistling past the bias graveyard.

If you notice mistracking, and you know SRA and VTF are pretty close to right, that’s the time to play with bias.

In the Soundsmith spirit, you could set it with a test record, and then cut it back 50%. Since it is dependent on vinyl composition as well as on groove modulation, you’re still not going to be on the money most of the time, but your tip might last longer.

All of this stuff is better left to ears than calculations. And I say this as a PhD trained ME who spent more than half his career developing mathematical models and searching for optimal configurations and controls.

Sometimes you just have to accept that the best choices are dependent on things you can’t really practically measure. And so you fly by your ears, not your calculations.

If it sounds good, it is good.
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Re: Anti Skate Take 2

Postby edw » Tue Sep 15, 2020 11:09 pm

Peer Gynt wrote:All of this stuff is better left to ears than calculations. And I say this as a PhD trained ME who spent more than half his career developing mathematical models and searching for optimal configurations and controls.

Sometimes you just have to accept that the best choices are dependent on things you can’t really practically measure. And so you fly by your ears, not your calculations.


No disagreement here, but you can measure THD on both channels to dial in A/S. While THD will increase as you get closer to the spindle, maintaining close THD between channels and also minimizing THD overall near the end of the LP does seem to get A/S working correctly. At least that is what AnalogMagik's antiskate LP/test tries to do. It has confirmed the need for A/S in one setup and no need for A/S in another setup.
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