Tracking error distortion audibility


I recently unpacked my turntable from a couple of years of storage. It still sounds very good. Several times during playback of the first few albums I literally jumped from my chair to see which track was playing as it sounded so great. After a while I realized the "great" sound was always at one of the "null" points. They seem to occur at the approximately the proper place (about 125mm from spindle) and near the lead out groove. Questions:
Is this common? I have improved the resolution of my system since the table's been in storage but I don't remember hearing this before.
All others geometric sources of alignment error not defined by the null points (VTA, azimuth etc.) are essentially constant through out the arc correct? If so they should cancel out. I assume the remedy is a linear tracking arm but I am surprised at how obviously better the sound is at these two points.
Table - AR ES-1, Arm - Sumiko MMT, Cart. - Benz Glider, Pre - Audible Illusions, Speakers - Innersound electrostatic hybrid
Do linear arms really sound as good across the whole record as I hear at only the nulls with my set-up?
feathed
I think we can all agree that alignment is difficult to get spot on and visual means have many inherent inaccuracies. To me this screams out for verification with a test record and instrumentation. I would think it possible to measure the distortion and confirm the positions of the nulls. You can then position them to agree with whatever formula you prefer or fine tune in combination with listening tests. I thought I remembered 20 years or more ago one could bring his or her table to a dealer and they would analyze the output to assess alignment. Did or does such a thing exist?
Dear Thom mackris: +++++ " who can achieve the same audible results with a two point protractor as I can with an arc protractor is ....." +++++

any one can do it if the two null points protractor is " works "/designed in almost perfect way and if what you are comparing against the complete arc protractor is the same: Baerwald vs Baerwald or Loefgren vs Loefgren or whatever.

This adjustements is not " black magic ", it is almost easy maybe the subject is that many people do not have the right know-how/exprience about, I hope that you can do it in the same way than Frank and many other people.

I don't know why so many put this subject arc protractor like something " unique " or sophisticated, because IMHO it is not.

Maybe I'm missing something but IMHO it is " crazy " to me that the only way ( almost ) to go is through an arc protractor when a two point one is an " arc ", my God!

I think that the first real target to everyone of us is try to match the tonearm and the cartridge making a in deep research before making a choose about.
Like you say there are " thousands " of words on this thread subject when the main subjects/basis/foundation about tonearm/cartridge is a little not discuss in deep.

Anyway everyone is totally free to post anything on this open forum, that's the way things are and nothing wrong with that.

Regards and enjoy the music.
Raul.
Hi Raul,

You may be one of the exceptions, and that would put you in Frank Schroeder's class of setup wizards. I was of the same opinion that you were before I started experimenting with this last Spring.

I have an old Ortofon, mirror-backed acrylic, two point protractor that I never let out of my sight. I dreaded losing it because it had very fine lines which gave me great insight into correcting for parallax when aligning at the two null points.

It now sits in my historical archive (a.k.a. "junk bin").

Cheers,
Thom @ Galibier
FWIW Maybe not on the current subject as I don't wish to debate protractor merits.
Since audibly my null seemed to be at about 128mm and since Lofgren B seems to be most correct as I don't hear inner groove distortion and both Lofgren B nulls are nearer the middle grooves, I increased my cartridge overhang and it did seem to sound better. I wouldn't suggest trial and error by ear as at least I can't be that precise with just my ear so I got out my protractor. I use the DB Systems. I found it very easy. Lofgren B did require about 1mm greater overhang and 1.000 smidgen units counterclockwise rotation.
Regarding alignment tools that require input of pivot to spindle length, I can't accurately measure that because of my arm's pivot design. For the system cited above where one uses the manufacturers pivot to spindle distance, No one drills the arm board where the tonearm maker specifies do they? Unless of course you have fixed cartridge mounting holes. If you have slotted mounting holes one should always mount your arm further from the spindle so as the maximize effective length and minimize tracking error. I've not read about this but I just assumed everyone did that.
What about alignment of the stylus to the cantilever? A misaligned stylus renders all methods discussed above (except maybe listening) null and void. They are utterly and completely useless.