How to use Feickert Protractor on SME V Tonearm

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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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.

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

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.

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.

I bought the SME V arm used and its missing the rubber grommet that fits onto the SME provided protractor alignment tool which fits it to the spindle, plus I have read that the Feickert protractor is much more accurate than that tool.

If you like the chosen alignment for the protractor that SME supplies, that is a precise way to get the alignment right. I like those bespoke protractors that require you to get the arm to align with a profile of the arm that is drawn on the protractor. The Basis Vector utilizes such a protractor and if you are off by just a fraction of a millimeter, the image will be off by a significant amount.

Oscar44, thanks. That is what I thought but wanted to hear from somebody that has used the Feickert with a SME V arm. Anybody else who has the SME V arm and uses the Feickert have any other advice? Should I start out the alignment setting the arm to 215mm and then go from there?

I don't have my Feickert with me (on long-term loan), but, if I recall correctly, it offers both a one-point (no need to iteratively move the protractor) or the two-point (like the Mint mentioned above) alignment (protractor must be moved).

For the one-point alignment, you will be select the curved line on the protractor that matches the type of alignment you want to use. You MUST then use the tool that also determines the pivot to spindle distance to correctly align the whole protractor. You should use something to wedge and hold the platter firmly in this position because this alignment of the protractor must not be moved. Next, for the alignment you want to use, look along the curve to find the marking for 212mm (your pivot to spindle measurement). At that point along the curve, you will also see a thin crossing line which is what you use to align the cantilever. You must not move the protractor at all using the one-point method.

As a check on this alignment, the Feickert also offers two-point alignment using cross hatched squares around the two null points (after all, getting tangency at these two points is the purpose of the alignment). Using the two point method does require moving the protractor to see if, when the need is placed at both points, the cantilever achieves tangency at both points. I think that the two-point method is more accurate because it does not require perfectly accurate measurement of the pivot to spindle distance, it does not require that the protractor be in the perfect position (the measurement spike perfectly aligned over the center of the pivot), and it will achieve the desired alignment even if the pivot-to-spindle distance falls somewhere off of the perfect 210, 211, etc. that is provided for using the one-point curves.

I've done this with an SME V -- you are right, you do have to adjust both the Feickert and the arm sliding base iteratively but it's not as endless as it seems -- you sort of reach a space pretty quickly where the stylus reaches the target point and the Feickert downpoint is on the pivot. It's bit like trying to adjust a length of telescoping tube by pulling out both ends at the same time, if that makes sense. Just try it and you'll see. And be sure to double check the stylus and the pivot settings each time.

Now what exact pivot to stylus distance you end up with by doing this will not likely match any pre- specified length but you will have your cartridge fitting the target of the Feickert design. Compare it with where the alignment is set using other methods then give it a listen.

I use the Mint and supply Yip the cantilever length and he builds a protractor that accommodates the correct spindle to pivot distance for SME as well as obtaining correct overhang.

I don’t know of any other tool that does this. The problem arises with SME “assuming” that everyone follows the rules and builds their cartridge according to industry standard.

Problem is everyone thinks their cantilever and diamond assembly is “the” industry standard so SME arms can wind up perfect or off quite a bit.

I love the SME V-12 so I have several Mint Tractors, one for each cartridge I choose to mount.

Truth is, unless you have a custom protractor you’re hoping SMEs numbers and the cartridge manufacturers numbers match. The Mint is only $90.00 so it’s a cheap investment.