Hi Raul,
Not a lot of itme these days, but this thread was brought to my attention by a couple of customers.
Up until this point, I have been recommending arc protractors for owners of all tonearms with adjustable headshell slots. The Mint combines availabilty and high quality.
The Schroeder Reference, Reference SQ and DPS arms are a challenge, because different cartridges yield different effective lengths (I know you know this). I try to make it easy for my Schroder customers and I send them card-stock protractors made for the effective length that their cartridge yields.
After that, it's up to them if they want to order a Mint or a Wally, or whatever.
At my suggestion, the Durand Talea has a small nipple on the underside of the bearing. Joel supplies a machined aluminum bar that mates to the record spindle and the nipple to adjust the pivot-spindle distance to within about .004" (some intentional play in the record spindle hole due to turntable manufacturer variances). A quality protractor brings you to the last .004" by rotating the arm (or, on a Galibier, by adjusting the armboard with its vernier, fine adjustment).
I appreciate the heroic effort undertaken by Dertonearm. I don't take this lightly, but there are some big claims being made, and I want to separate the issue of chosen geometry from how well a tool achieves the geometry.
On the subject of geometry, I found the ad, and noted that the protractor allows for Baerwald, Loefgren, and Stevenson for both IEC and DIN (6 combinations). I must have misread an earlier post about another alignment geometry being employed.
So an experiment using the Unitractor and the Mint (note that I did not use the word "shootout") would have more validity. Only 6 protractors need to be made for it ;-)
There are some nice usability features on Dertonarm's design, and these should not be underestimated. The fixed position magnifying glass (set up for the focal length of the magnifier, it would appear), will help many.
So, everything counts when you're trying to design a new product. A more "accurate" tool that a large variety of users cannot effectively use is not as good as one that is slightly less accurate but more users can use to its full potential.
I need to make something clear. I am NOT saying that the Unitractor is less accurate. I am merely pointing out that ease of use is is an important feature. Nothing more.
Cheers,
Thom @ Galibier