Why use a super accurate cartridge protractor

Hi John_Gordon -
Interesting you should mention offset angle. One of the strengths of the Phantom jig is angular alignment of the stylus/generator.
It's an old article I know, but it stuck in my mind because of it's relevance. Scroll down the link to "The Need For Precise Setup":-

http://www.positive-feedback.com/pfbackissues/0605/gordon.tonearm.6n5.html

The author's results were very thought provoking....

Protractors are great for aligning horizontal azimuth and effective length with any precision for a given SRA/VTA range. Vertical azimuth, SRA/VTA, and VTF are usually adjusted by ear. Although we can set AZ by eye, that doesn't necessarily equate to the best and usually takes final tuning by ear. In other words, the use of a protractor is only part of the alignment process. My 2 cents worth.

A note. MintLP Best Tractor is accurate to the 2nd digit of a millimeter. It is simply a more precisely printed loefgren A, arc protractor with the added benefit of parallax effect for sighting. Assuming one has the optics and eyesight to use it properly, it allows for alignment of the stylus, not just the cartridge body.

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.

Hi Dan_ed
The Mint Protractor you refer to,

accurate to the 2nd digit of a millimeter

does that mean to 1/100 of a mm? And what did you mean by

...aligning horizontal azimuth and effective length with any precision

This is one of my points that, while there are figures for how precise the protractors are made regarding linear dimensions, there is nothing regarding angular ones. Even in the case of the Graham jigs mentioned by Moonglum, there are no numbers, so we don't know by how much things are improved by using the jig, ie how much angular adjustment is required. Or ultimately, by how much the stylus is out of alignment on the cantilever, how much the cantilever is out of alignment with the generator, and how far that is out re the body. Of course that is a big ask...!

You are totally right regarding the rest of the adjustments - I agree that a protractor is only part of the set up process - and the other parameters can have big effects.
John
.

Hi John,

Yes, I understand that to be the precision of the protractor in all regards. Maybe a good question for Yip. I assume that the lines orthogonal to the groove are drawn to the same precision by a computer.

When I align on a Mint I am not concerned at all with the orientation of the cantilever, within common sense. ;-) What I mean is that I align the stylus to the lines and not anything else. The lines, as tiny as they are, are still a bit wider than the stylus so I'm twisting ever so slightly while staying within the bounds of the line. Whether the stylus may need a bit more twist to the right or left is a pretty tough call. Perhaps this is the angle you refer to? I admit I am still at the mercy of how precisely the protractor is drawn as well as printed.

To the thread question. Even though there may not be good tools for setting all of the parameters I do find that using those that are available do indeed give me better results. I think it is possible to get just as good of results with most protractors, but I find that the extra precision does help me get repeatable results as I do switch cartridges and arms fairly often.