Why use a super accurate cartridge protractor

Dear Thekong, dear Nandric, we should in specific worry about where on the groove's radius the maxima and minima are located. The groove's walls do change with decreasing radius and thus do the conditions for the stylus' polished areas. Thats why high derivations from the tangential zero are most "lethal" to the sound towards the inner label.
Cheers,
D.

Hi Thekong, the null points will shift and the curve will be a different one. If you go to Vinyl Engine and play a bit with the alignment comparator - you will see, that small alternations have huge impact.
Cheers,
D.

Dear Thekong, the alignment I did choose actually minimizes distortion in the last 2/3 ( not just last 1/3) of the record groove's radius.
Cheers,
D.

Dear Cocoabaroque, when Loefgren and Baerwald calculated the respective tangential curves (Baerwald/Loefgren A and Loefgren B), they did do it for monophonic records to be tracked with round styli of approx. 60 µm radius.
Stereo microgroove and fine line or similar styli with polished area of 1µm x 5-6µm weren't in sight at all.
A stereo record's groove is not a homogenous track at all and the differences in radii between the groove's two walls do increase with decreasing distance to the spindle.
In other words: the tracking conditions for a stereo stylus do change ever more towards the groove's lead out.
That's why some designers did choose alignments different from the "old masters" and that's a reason why so many modern audiophile records have rather long dead wax - avoiding the ever more problematic situation close to the inner label.
When Loefgren made his calculation's, our grandfathers were young men and our parents were in pampers. This was almost half a century before micro-ridge, vdH 1 or fine line styli first saw the light of day or the walls of a MFSL LP.
A spherical 60µm needle tracking an old wide groove record has a much easier job.
No worries there about soundstage recreation, increasing differences between left and right groove wall contact areas.
Keep enjoying the discussion - off for 2 week holiday in Africa now,
D.

Löfgren just used euclidean geometry - as does did everybody before/after him in the past 2260+ years in the western hemisphere - be it in tonearm geometry or any other geometrical topic related to mechanics and 3-dimensonal space on earth.
He was however unquestioned the first to muse and care about giving phono playback an optimized geometric solid basis.
And every analog audiophile should be grateful for his attempt.
I for one certainly am.
Viewed in the light of fact that there is a wide diversity of stereo records since 1958 with groove cut area varying by a wide margin, his preferences and weightings aren't as universal applicable as they were in 1934/38.

Dear Nikola, spindle diameter variations are usually between 7,00 to 7,25 mm - so we are talking derivations between spindle diameters of maximum 0.25 mm.
As long as one tries to be as precise as possible in as many parameters as possible, it is at least a suitable way to get close to a precise alignment.
If the inaccuracy however builds up and adds ever more with the number of parameters "not cared that much about", one may (not need to - by dump luck) get not an alignment, but a "guess" which may be way off.

Why use a super accurate protractor?
Simply because it helps to get the best (read: best sonic performance) out of your cartridge/tonearm.
Would you use an expensive high performance Porsche or Mercedes (Audi, Jaguar - extend at wish ...) with old worn tires suitable for a 1955 beetle?
Not using an as precise as possible alignment ( = super precise protractor ) is simply giving away possible sonic quality and putting the whole performance of one's audio set-up at risk (sonic wise).
It is as easy as that.
If one doesn't really care about sound and possible wear of his/her records - fine, no problem (at least not mine).
But then the question arise why spending hundreds and thousands of dollars for analog playback at all?
CD-players are cheap to get and don't need a protractor (at least not a super precise one ...).
Cheers,
D

John_gordon, no so far there isn't a new formula.
But then - is there really a need for one?
Given the wide variation in records grooved radius, there is no "royal device"/Königsweg.
The user/operator/analog enthusiast ultimately has to choose the alignment he/she (it..?) prefers.
This choice should be based on the majority of the records in one's collection.
Lucky audiophiles out there with multiple tonearms at hand (Halcro?, Nandric?, Downunder?, Thuchan? ..) might go the way of using different alignments and thus serving all the different records - each with the best suitable alignment.
"My" preference is based on the majority of my collection (mostly US and british records pressed in the late 1950ies to early 1970ies - many with very short dead wax/lead out groove) my preferences in sonics (big and detailed soundstage and up-front, dynamic live-like sonic "picture") AND finally my experience that 0.8% distortion in the lead-in groove are far less sonically "obstructive" (in the negative aural sense) as they are close to the inner label.
Add to that my addiction to big symphonic music, opera and 1950/60 Jazz with many big crescendi towards the end of movements and I have yet another good reason for trying to reduce/minimize distortion in the last 2/3 of the groove.
This of course would in no way apply to a collection of 1990ies to 2010s modern audiophile records where the groove quite often doesn't even come close to IEC inner limit.
I am quite happy that we have a selection of different alignments to choose the appropriate for each collection/preference.
In any case - off now for holiday till mid-september.
Kind regards to everyone and a sunny august!
D.

A note - as I am not yet off the computer.
A protractor with just a helping line saying "please rotate till this line points toward the pivot" (talking about eyesight and good target....) has certainly potential for increased accuracy.
The laser lines on the UNI-templates/UNI-Protractor are accurate to the 3rd digit of a millimeter.
The lines are the smallest possible in laser-engravement.
All templates are with 3mm deep true parallax.
The UNI-Protractor's templates allow for alignment of the stylus and cantilever - not just the cartridge body.
It does so for ANY effective length and ANY pivot tonearm to ANY tangential curve desired.
Add to this the fact that most owners of the UNI-Protractor - more than 70 by now - did already own one or more MINT and other protractors before purchasing the UNI-Protractor.
Before I did design the UNI-Protractor I did collect samples of all the other protractors on the market - past and present.
Those 70+ fellow Audiogoners who have worked with the UNI-Protractor already know exactly why they bought this comparatively high priced tool.
Because of it's precision, unique universality, build quality and - last not least - outstanding sonic results.
Cheers,
D.