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
Dear Axel, as for your quote:

"""""A lot of folks don't want to know the details of their car's differential gear, but simply use it.
So, that said, it might make a case for Linn and SME's non-variable approach.
I'm also not really sure if a very 'funky' adjust-all approach is the last answer to all this."""""

The reason why today we can just enter the car and drive without knowing the details and without having to adjust some things before starting the engine is, that in the past 100+ years a lot of well-educated engineers have put endless work into the complex topic "automotive car" and have solved all problems (and there were an endless number of problems in the early decades and still today cars are improving).

We are far from that state of development with analog front-end.
Far less time, far less high-trained manpower, far less money.

Till we can use analog front-end with the same ease as our cars, I will have a long white beard...... and I am not that old yet.
:-) Dertonarm,
Mine is not long, but white for sure, and SME's founder is dead by now.
It must have been at least their intention to move on with all this fiddly-dilly alignment stuff. I feel obliged to give them credit for it, even one can't agree with it all at times.

Incidentally, I just learned by John Carr himself, that Lyra got it right on target with the stylus-tip to mounting hole-distance 3/8" = 9.52 mm tolerance +/- 0.3 mm.

So, yet another step in the right direction.
Get a Lyra, get an SME, and stop worrying about your 'differential'-> alignment(s).
Jolly good show, I say!
Best,
Axel
Maybe one of the " weird " tonearms ( on stylus alignment ) was the SAEC 506/30: the builder specs are 295mm on effective length with 9mm on overhang ( many trouble with some cartridges because to achieve 9mm there is almost no space in the SAEC headshell for the cartridge connector pind and the headshell wires. ), where the pivot to spindle distance is 286mm.

Well if we run Baerwald with that EL ( 295mm ) then we have an overhang of 13.8mm that give us a pivot to spindle distance of 281.2mm.

I wonder why SAEC made this compensation ( 5mm ) with the whole numbers where they choose the overhang of 9mm that was a pain for say the least?

Regards and enjoy the music.
Raul.
Dear Raul, I will set up - for a friend of mine - a SAEC-506/30 in two weeks - mid May. I will have some news and geometrical details after I have done so. If anyone interested, I will gladly supply all findings.
Other SAEC the WE8000/ST has 13mm with 302mm in EL as manufacturer specs but through Baerwald/Lofgren calculations we have: 13.5mm/13.9mm on overhang.

So I think that the SAEC owners could try those overhang calculations on it and in the the model 506/30: 13.8mm in overhang and 281.2mm on pivot to spindle distance.

Regards and enjoy the music.
Raul.