The “Korf method” for azimuth alignment

[tony22]

The thread title refers more generally to azimuth alignment that targets stylus perpendicularity to the groove as the goal for optimal azimuth, using either distortion or HF measurement as the method. I imagine most vinylistas already know about this technique, but for those who do not, here’s the link -

Azimuth Adjustment Myths and Reality, Part I

korfaudio.com

The stylus perpendicularity method essentially ignores shooting for equal channel separation. I hadn’t read this in some time, and after seeing it again I wondered what parameter is being used by the old Adjust Plus+ or AnalogMagik v1 or v2 - or even the Fozgometer - for setting azimuth? Generator alignment I guess? I’ve spoken with Peter Lederman a few times about azimuth, and he points out that at least his own carts when properly aligned, given their very high channel separation to begin with, can have different numbers from L>R and R>L. That would suggest (what I’ll keep calling) the Korf method is a more useful technique, keeping the stylus from excessive vertical skew because of maybe shooting for the wrong goal. Wondering what other folks think.

 

[mtemur]

I wondered what parameter is being used by the old Adjust Plus+ or AnalogMagik v1 or v2 - or even the Fozgometer - for setting azimuth?

They all use the correct method, maximum channel separation and minimum phase error.

The thread title refers more generally to azimuth alignment that targets stylus perpendicularity to the groove as the goal for optimal azimuth, using either distortion or HF measurement as the method. I imagine most vinylistas already know about this technique, but for those who do not, here’s the link -

Korf blog contains some useful insights for vinyl playback but their azimuth method is not one of them. When you read the blog you get a feeling like every manufacturer before Korf is stupid and cheated us with poor products. I don’t know maybe it’s just me or their writing technique. Of course there is some reality in their assumptions but not as dramatic as they portrayed. IMHO take everything in Korf blog with a grain of salt. I still believe that their tonearm can be incredibly good though.

I used to think like them about Azimuth in the past but soon I realized perpendicular stylus is not the correct way. Scanning sides (edges) of stylus in contact with groove walls are not straight lines. They’re rather like an arc or hyperbolic.

What is the benefit of arc shaped edges on a stylus? Well, when the stylus is tilted to one side 1-2 degrees it will still be in perfect contact with groove walls. Modern profiles are cut like an arc on the edges and tip for this purpose rather than straight lines. Don’t let illustrations on the Korf blog fool you. They’re drawn as a triangle.
I don’t want to use their illustration without permission. It’s similar to the one below

It is illustrated as if stylus shape is a triangle with straight lines on the edges and whole triangle fits inside the groove. But in reality stylus is not triangle and only a small part of the curvature area fits inside the groove as you can see below. And that area is close to the tip which has a curved shape. So, modern profiles are not exactly circular shaped like a spherical but still keeps contact with groove walls up to a couple of degrees tilting.


As a result it’s better and correct way to adjust azimuth according to maximum channel separation and minimum phase error up to 1-2 degrees. If You need to tilt more than that than change the cartridge or use it as it is. Reducing phase error is more important cause human ear is very sensitive to phase error. IMHO using AP test disc is very good for setting azimuth.

 

[tony22]

Korf blog contains some useful insights for vinyl playback but their azimuth method is not one of them. When you read the blog you get a feeling like every manufacturer before Korf is stupid and cheated us with poor products.

Right! I'd been using the accepted methods for years and I go back again to this blog and see this again.

As a result it’s better and correct way to adjust azimuth according to maximum channel separation and minimum phase error up to 1-2 degrees. If You need to tilt more than that than change the cartridge or use it as it is. Reducing phase error is more important cause human ear is very sensitive to phase error. IMHO using AP test disc is very good for this purpose.

If the goal is to get maximum channel separation and minimum phase difference, it seems a tradeoff will have to be made if phase difference is the priority. That would suggest Adjust Plus+ as being perhaps a slightly easier tool to use for this purpose (at least IMO). AM does provide phase numbers but I think the graphing technique used by AP makes it easier to "see" where things are going as the cart is rotated. Having said all that, we've all had the discussion in another thread about the numbers between AM and AP not being the same for azimuth. Beyond that I've had numbers be virtually dead identical from L>R and R>L with AM and be unequal in AP, and vice versa, ignoring the values not being close.

 

[mtemur]

If the goal is to get maximum channel separation and minimum phase difference, it seems a tradeoff will have to be made if phase difference is the priority. That would suggest Adjust Plus+ as being perhaps a slightly easier tool to use for this purpose (at least IMO).

It looks like Adjust+ is easier to use but I’m not sure if it’s better than AM. Normally -but not always- phase and best channel separation coincide.

Beyond that I've had numbers be virtually dead identical from L>R and R>L with AM and be unequal in AP, and vice versa, ignoring the values not being close.

I get equal numbers for L>R and R>L on both AM and AP discs only on vacuum hold down platters. Numbers are not the same but equal on both channels, something like 28dB for AM and 35dB for AP. Other than vacuum hold down platters I still reach to the same adjustment using either test disc but presented numbers are only equal with AP disc. What I’m trying to say is both test discs lead you to the same correct adjustment when you try to achieve highest possible numbers for both channels. If they’re also equal it’s even better.

 

[tony22]

but presented numbers are only equal with AP disc

I do get the best coincidence of results with the Analog Productions Ultimate Analog (I’m hoping that’s the one you’re referring to) test record. The AM and the Adjust Plus records when used with their respective programs yield the differing results I see. Makes sense I guess. Nobody really knows how well all these test records are cut and pressed. And for some reason Mikey doesn’t seem to like the Adjust Plus disc for azimuth.

 

[mtemur]

I do get the best coincidence of results with the Analog Productions Ultimate Analog (I’m hoping that’s the one you’re referring to) test record.

Yes, that’s the one.

 

[tony22]

You're right of course, @mtemur. I got out the Ultimate Analog test record, and after a tiny (and I mean tiny) bit of tweaking I got Adjust Plus+ and AMv1 to show almost identical (off by a couple of tenths of a dB) azimuth readings, on both programs L>R and R>L off being identical by .4 dB. Good enough for me. APlus shows the phase delta to be 4 degrees. Hoping that's low enough. Trying to get that any smaller was an exercise in frustration. And as others have noted, when all that was done I looked at azimuth on AMv2, with the v2 test record (since on v2 azimuth can't be done with separate L and R tracks) and the difference was on the order of 12dB. Really not sure what to think about that, as two other programs (oh, and the Visual Analyzer SW oscilloscope) all show very close results to each other.

 

[mtemur]

You're right of course, @mtemur. I got out the Ultimate Analog test record, and after a tiny (and I mean tiny) bit of tweaking I got Adjust Plus+ and AMv1 to show almost identical (off by a couple of tenths of a dB) azimuth readings, on both programs L>R and R>L off being identical by .4 dB. Good enough for me. APlus shows the phase delta to be 4 degrees. Hoping that's low enough. Trying to get that any smaller was an exercise in frustration. And as others have noted, when all that was done I looked at azimuth on AMv2, with the v2 test record (since on v2 azimuth can't be done with separate L and R tracks) and the difference was on the order of 12dB. Really not sure what to think about that, as two other programs (oh, and the Visual Analyzer SW oscilloscope) all show very close results to each other.

I believe 0.4dB channel separation and 4 degrees phase differences are extremely good. I have similar experience with AM test record.