Vinyl Asylum Welcome Licorice Pizza (LP) lovers! Setup guides and Vinyl FAQ.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Vinyl Asylum ]

---

[ Alert Moderator ]

---

RE: Fremer's ZENITH ANGLE CORRECTION or have we all gone crazy.

Posted by flood2 (A) on February 14, 2021 at 23:17:38

In Reply to: RE: Fremer's ZENITH ANGLE CORRECTION or have we all gone crazy. posted by dave slagle on February 11, 2021 at 09:59:51:

Hi Dave

That's very interesting!

I was just having a good think about the point you raised about the issue of phase vs tracking error over the last few days.
If I may just go back to the issue of tracking error in relation to a long groove wavelength (relative to the radius of curvature for the scanning surface) and how it causes distortion - if the cantilever axis is not tangential to the groove then the movement of the cantilever is not perpendicular to the groove and this results in a distorted waveform with an FM-like distortion that is related to the groove wavelength. With a conical stylus, the points of contact are such that the line joining them is always perpendicular to the direction of the record motion and matching the cutter. I am sure that this is why a cartridge such as the DL103 has such ardent fans. With an elliptical or line contact stylus, the contact points are no longer perpendicular to the groove wall except at the null points and tracking error introduces the phase component which makes these styli far more sensitive to tracking error.
So the question is if, for a groove wavelength that is very much longer than the radius of curvature of the scanning surface, the tracking error due to cantilever alignment still dominates? It is not until the groove wavelength decreases sufficiently that the phase error due to the zenith compounds the problem. However, nulling a zenith error doesn't solve the distortion due to the cantilever tracking error and that you are still introducing an FM distortion to the signal.

I don't know the answer. Maybe zenith distortion dominates particularly for line contact styli and this IS the right approach, but I can't help thinking that "two wrongs don't make a right" and I think that shifting entirely to nulling zenith at the expense of the longer wavelength FM distortion due to cantilever tracking angle doesn't solve the problem. I have a number of styli that have a zenith error, I may do the experiment. However, I have not found setting the offset to be particularly consistent and I normally consign faulty styli/cartridges to the reject pile and move on to suitable candidates that are worth the time and effort!

The test method you described sounds a clever way to determine IMD.
I have the Ultimate Analogue Test LP and also didn't find the VTA test terribly useful given that the VTA is essentially pre-determined by the cartridge manufacturer and is also has a fixed relationship to the SRA.

One thought came to mind in relation to the position on the record for the VTA test - it is centred at a radius of around 100mm. For a typical 9" arm set to the standard 66/121mm nulls, the tracking error is about 0.9° with a estimated distortion level of about 0.5%. Therefore wouldn't adjusting zenith for the minimum distortion not be changing the alignment completely? Surely one would be trying to set the distortion to the equivalent value based on tracking error? If on the other hand, the you had a suitable test tone centred around the nulls, then perhaps your method applies directly.

The original Ortofon (0001 and 0002) test discs have a difference-tone test stepping down from 20/19 kHz down to 8/7kHz which enable stylus condition to be monitored using the level of IMD as a metric. These are still available on discogs and I can recommend it to you as I find it the most useful of all my test discs (which includes the CBS STR-110 and 112 as well as the Telarc Omnidisc). In particular it has a white noise test tone which makes doing frequency response checks a breeze!


Regards Anthony

"Beauty is Truth, Truth Beauty.." Keats

This post is made possible by the generous support of people like you and our sponsors:

Sonic Craft

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---