Elliptical?

[dlaloum]

Hmmm - would THD measurements at 15kHz identify and seperate a 0.7mil conical/spherical from a 0.4mil eliptical?

And if so what would the expected difference be?

ie: is there a functional way of measuring it with a test record?

[Bran Kulez]

Since taking a renewed interest in my vinyl collection and subscribing to this forum a couple of years ago, I've read over and over again that a conical stylus will reduce pops and clicks or roll off the high end more so than an elliptical. I'm wondering if these comments are based on actual listening experience or just simply repeating manufacturers marketing claims. I personally have not done any critical listening in this regard but would like to do so in the near future.

[Ldg]

Hmmm - would THD measurements at 15kHz identify and seperate a 0.7mil conical/spherical from a 0.4mil eliptical?

And if so what would the expected difference be?

Well, THD at 15kHz is inaudible anyway, not to mention tricky to measure well. In any event, one doesn't have to go to hf to measure difference, in principle. Pinch effect relates to groove angle, not curvature, so is level related. And should show up in principle even at 1kHz at high enough levels.

Some time back, I included a pinch effect distortion calculator in groovy.xls. It lets one explore pinch effect, amongst other things, and it's here :

IN PRACTICE, however, other factors than stylus profile tend to dominate THD performance. For example, Paul Miller publishes distortion measurements based on 0dB level (ref 5cm/s) at 1kHz. In these tests, the DL103R is better than the 2M Red by far, and the 2M Black by a little. AT OC9/III and AT440MLa are better than all, but not that much better than the DL103R.

Such things, and my own listening tests, led me to conclude that popular opinion of the audible effects of distortion arising from spherical profile styli is often greatly exaggerated. In normal programme material. As Bran K suggests, I also concluded that much marketing hype might be responsible.

What's near impossible to do is try a substitution where just the stylus profile changes. Not the cantilever, suspension, azimuth, rotation/shank alignment, VTA etc etc. That makes it near impossible to be conclusive about measuring, or listening to, effects of stylus profile in isolation, as I see it.

Sphericals have a couple of advantages too. Easier to make to close tolerance of geometry and polish. Easier to mount on the cantilever, eliminating zenith alignment contribution to overall tolerance. Lower friction, improved trackability and surface flicker noise. Can be run at higher VTF, better trackability. Base clearance can be better, lower surface noise. But some of these advantages might equally apply to 'quasi sphericals', or 'bi-radials' as described on this thread, of course.

[missan]

Has anyone looked at the Denon sphericals closely?
missan

[Ldg]

Hi missan. I found this. Credit sidandcoke for the original image :



http://imageevent.com/sidandcoke/upclos ... =2&s=0&z=2

It's side on, so can't see the nitty gritty, also mag/scale doesn't allow to see detail near contact region. But, it's a square shank (grain aligned ?), and polish appears fine, as best one can tell. Hopefully someone can post the scoop frontal zoom shot !

[Ldg]

Hi missan, here's a front shot of my moderately worn Stanton 500 spherical :



It is a decent performing spherical. As you can see, geometry is good, polish is good. It's a circular shank. There are no ground flats.

[missan]

Hi LD.
Thanks, I don´t know why I had the feeling that I´ve seen Denon´s sphericals somewhere, and they had a cut front/back. Guess I was dreaming.
missan

[Hepokatti]

Excuse me for being an idiot, but explain me how "front/back" cuts in an elliptical stylus improves contact area with groove wall over spherical? I've always thought that ellipticals are just cut sphericals. Or are the cuts made on sides? I'm really confused.



Here on the left side there is an elliptical stylus, and to my eyes it looks like the cuts are in front (and back). How this improves groove wall contact? :O

[dlaloum]

In theory... (based on that article) - after the front/back cut, they are supposed to get another stage of grinding/polishing achieved via tumbling....

[Ldg]

Yes. The issues are to what extent, if at all, does that extra step happen, and what does it actually achieve? Because if one looks at common ellipticals, the radius on the cut edge, if present at all, typically appears too small to participate or achieve anything.

The image Hepokatti posted is a marketing sketch, unfortunately and has some howlers which are misleading. The scale, especially shank, is hopelessly out, as is proportion. Drawing of the groove is below absolute limit spec for minimum groove depth, IIRC. Bottom clearance looks wrong. It seems to be drawn to convey a marketing concept, which I'm not even convinced is real.

Here's a markup of that image with actual front images of elliptical and FG styli to scale, and you'll see what I mean. In any event, I think this illustrates more realistic contact locations and proportions, and where the elliptical grind, and cut edge, is in relation to it. NB the overall groove depth is too shallow, I think, but that does not change the contact locations or fit :

[flavio81]

Here on the left side there is an elliptical stylus, and to my eyes it looks like the cuts are in front (and back). How this improves groove wall contact? :O

I don't think the elliptical improves contact respect to the conical. Makes no sense.

[flavio81]

Yes. The issues are to what extent, if at all, does that extra step happen, and what does it actually achieve? Because if one looks at common ellipticals, the radius on the cut edge, if present at all, typically appears too small to participate or achieve anything.

The image Hepokatti posted is a marketing sketch, unfortunately and has some howlers which are misleading. The scale, especially shank, is hopelessly out, as is proportion. Drawing of the groove is below absolute limit spec for minimum groove depth, IIRC. Bottom clearance looks wrong. It seems to be drawn to convey a marketing concept, which I'm not even convinced is real.

Here's a markup of that image with actual front images of elliptical and FG styli to scale, and you'll see what I mean. In any event, I think this illustrates more realistic contact locations and proportions, and where the elliptical grind, and cut edge, is in relation to it. NB the overall groove depth is too shallow, I think, but that does not change the contact locations or fit :

You made that image? This is a masterpiece! Great!

[Ldg]

Thx flavio81 ! The FG could be clearer, but the gist is there. Especially for the elliptical.

[Hepokatti]

Thank you ld. Now it makes more sense

EDIT: Might vinyl deformation play some part in where typical elliptical shape could offer advantages pushing the deformed vinyl away differently? Or is the deformation even that big considering modern, rather low stylus pressures?