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
Feathed also made the same post on AudioAsylum, if you haven't seen it. Here is a quote from him:

"I just hope I get the alignment on the Alphason perfect to hear it at it's best. I suppose I should get my alignment template out and check for problems with my current setup. I hesitate though as my eyes are terrible compared to 10 years ago when I mounted the cartridge."

Looks like it's been 10 years since he's checked the cartridge setup.
With such knowledgeable folks as Raul and Thom attempting to carry the flag of reason, I'm a little hesitant to join the march. But I'll go ahead and step in line anyway.

Feathed stated "I on the other hand believe the presence of a slotted headshell is explicit approval to tweak." So I must ask, is there an industry standard for stylus tip location relative to the cartridge body mounting holes? Simply looking at the variety of body designs and cantilever lengths the answer must be no. Therefore, the slotted headshells (or slotted mounting base such as the SME) are intended to accommodate a variety of cartridges to be correctly mounted on a given arm/headshell. Fortunately, they also allow for minor adjustments if an arm is not mounted precisely.

I have been in this audio hobby for roughly 40 years and have included vinyl playback for the entire time. This is the first time I can recall anyone suggesting that overhang is arbitrary and can be set anyplace (i.e. at the end of the arm) at the user's discretion.
Hi Pryso,

The forward position of the stylus relative to the cartridge mounting holes is more of a statistical norm than an industry standard. Frank Schroeder has observed this norm to center around 9.25mm.

I know the ZYX (Airy-3 and Universe) come in at 9.00mm, and the Dynavectors vary, but in general fall into the 8.00 to 8.25mm region. I haven't compiled as large a database as Frank has, but don't doubt his 9.25 number.

SME's assumption is that you can compensate for these small differences in effective length by moving the arm for and aft in the track, to arrive at a workable combination of effective length (as dictated by your cartridge) and overhang/pivot-spindle.

In my early days at Galibier, I advocated this as well, using the articulated armboard to adjust pivot to spindle distance. To a certain extent, I trivialized the importance of offset angle as does SME.

While I now advocate the use of an arc protractor (certainly for precision in setting of effective length and overhang/pivot to spindle parameters), the importance of offset angle is still one that I would like to explore further.

In a conversation with Yip at MintLP, I posited that offset angle might be considerably less important than dialing in the effective length/overhang parameters (tracing the arc perfectly). Yip has been thinking the same thing.

Both of us however have been respecting all three parameters, and need to experiment with the effect of screwing this third one up (offset angle). Of course, with an arc protractor, it would be a simple matter of separating offset angle from the other two variables (e.g. tracing the arc) in order to observe the effects.

I'm thinking out loud here, but as I visualize the solution, a clockwise rotation of the cartridge (relative to that dictated by Baerwaald for example) would have the effect of shifting both your null points toward the record spindle. So, with a Baerwaald arc, you'd have an alignment that slightly favored the inner grooves as does Loefgren.

I need to both think this through as well as play with this a bit.

This concept of optimizing for the inner grooves at the expense of overall higher distortion in the majority of the record is an odd one to my way of thinking, yet I understand why the fellow who listens to large, romantic works with big climaxes might make this choice.

Back to our old friend, the SME ... Of course, there are two reasons for having a bit of play in the holes in the headshell holes - both of them relating to adjusting the offset angle: (a) due to an alternate effective length dictated by the fore/aft position of the stylus relative to the cartridge holes, and (b) to correct for "out of true" cantilevers resulting from normal production variances.

It's been too long since I owned an SME (an original Model V), but I don't recall much play in the cartridge holes in the headshell. I recall one poster commenting on this forum that he opened up the diameter if his holes a bit in order to play with offset angle.

Cheers,
Thom @ Galibier
Dear Pryso: +++++ " This is the first time I can recall anyone suggesting that overhang is arbitrary and can be set anyplace (i.e. at the end of the arm) at the user's discretion. " +++++

me either and the problem was/is that he never answer the " right " Dan question about the spindle to pivot distance. He say works with the DB protractor where you can't to measure any of those distances: effective length or spindle/pivot.

So everyone has to assume ( like you ) that the overhang and effective length were take it at " random " because there is no reference point taked about.

I think that maybe he has a misunderstood on the subject or needs an up-date but of course he can " drive " the road he choose it ( like it to us or not ) where he already has such " distortions " where only can have " great " sound around the lead out groove ( null pont ) due to its " odd " tonearm/cartridge set-up.

I'm with you, Halcro, Dan and Thom on the Feathed " argument ".

I always say that all of us ( in this forum ) have the opportunity to learn every single day from everyone: things are that we want it, a not always " easy " attitude.

Regards and enjoy the music.
Raul.
Hi Thom:

Of course I realize the headshell slots allow for offset adjustments as well as overhang. To simplify the argument (which seems to have become complex enough on its own!), I was focusing only on the overhang as it relates to individual cartridge dimensions. This was to address Feathed's quote regarding the headshell slots. And having met Brooks Berdan I will look forward to your report back with his take on this discussion.

I've never used an SME arm but it is fairly obvious that their mounting slot accommodates overhang adjustments. I hadn't considered their use of headshell holes rather than slots as limiting offset adjustments -- good point.

But as Raul points out, these forums are an opportunity to learn. So whenever anyone posts information that runs contrary to science or common knowledge there is also the chance to misinform. That is unless they can produce new proofs to support their position.