How to use Feickert Protractor on SME V Tonearm

Hartonr,

Without the grommet or a means to perfectly fit the protractor around the spindle, your SME-supplied protractor will not be very accurate. If you have the spindle to pivot distance accurately measured, I think that the Mint protractor mentioned above by others is the best way to go. They will make a protractor for that specific distance and with the correct diameter for the spindle hole for your turntable (spindle sizes vary by a significant amount (up to 2mm in diameter). What I really like about the Mint is that the mirrored surface is designed so that the lines come into sharp focus (no double images of the lines) only when you have moved your head into the correct position to correctly view the cantilever alignment to the markings. This correct head positioning IS critical to a super accurate measurement. Also, because the protractor is made specifically for your spindle to pivot distance, the placement of the null points is such that you do not have to iteratively move the protractor. It is the easiest thing to use and VERY accurate.

Larryi,

Fully agree with your latest, provided that SME owners pay heed to Albert's initial post. Use of a Mint (or any arc) protractor with an SME V requires that the user provide Yip with their cartridge's cantilever length (i.e., the hypotenuse of a triangle drawn between the stylus tip and the two cartridge mounting holes, when viewed from directly above).

Lacking this information, a protractor designer could not calculate the arc any particular stylus should follow except by guessing, which Yip seems uninclined to do.

Albert correctly explained SME's naive assumption as to cantilever length, which necessitates a unique Mint (or other arc) protractor for each cartridge. Whether SME was being shortsighted or haughty is open for debate, but in any event it's a weakness in an otherwise fine tonearm.

OK, I understand the use of the Mint protractor. The reason I went with the Feickert is so I can align my SME V with different cartridges. I did not want to measure each new cartridge and then get a new Mint protractor each time. So, please only give advice on how to align the SME V arm using the Fieckert protractor.

Thanks

As far as I know, SME did not assume anything about the cantilever length.
They assumed there would be an industry standard horizontal dimension
specification of 9.5 mm from the center of the cartridge mounting holes to
the stylus tip, regardless of the length of the cantilever. This is the
measurement that YIP at MINT needs to provide an accurate protractor to
customers who own SME tonearms.

I have precisely measured this distance on two of my cartridges. Fortunately,
they have the same mounting hole to stylus tip distance of 9.27mm so I can
use the same MINT protractor for both cartridges.

Yip needs this measurement so that he can calculate the pivot point to stylus
tip distance to accurately draw the currect radius for his arc protractor. The
offset angle of the headshell comes into this calculation as the radius is the
hypotenuse of a triangle formed by three lines: the pivot to stylus tip
(hypotenuse), the pivot to a point centered between the cartridge mounting
holes and the center point between the mounting holes to the stylus tip.

Once calculated accurately, the MINT protractor is an extremely good
alignment device.

As has been mentioned, any two point protractor can be used to set up an SME, or any other arm for that matter, irrespective of whether the arm base slides, the mounting board pivots, or there are slots in the headshell.

The SME approach which is based on a nominal effective length design predates all current production arms and has many advantages, and is neither naive nor ill considered. As has been mentioned not all cartridges are the same, and the SME design principle was based on that fact.

Arc protractors are a relatively recent innovation, and are dependent on accurate effective length measurement, so as as to enable the correct arc to be created, otherwise the are inaccurate. They also require accurate mounting of the arm to suit the effective length. The SME approach does not require the pivot to spindle distance to be fixed, therefore the arm mounting is not critical. it is adjusted to suit the cartridge. Understanding this is important and there is much misinformation about SME arms because of a misunderstanding of the basis of tonearm design, often on the part of those who should know better.

There is a description of SME geometry here
as well as other aspects of design such as the importance of spindle sizes, and protractors such as the SME and the Dennesen Sountractor.

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