Tonearm Alignment Calculator Pro

[JaS]

I'm not sure how useful this will be, but here's the improved version of my original alignment calculator, with enough bells and whistles that it's replaced both the alignment calculator and the alignment comparator, and gained the pro tag (!)

Tonearm Alignment Calculator Pro

Basic functionality is essentially as before - enter either a pivot to spindle or effective length value, hit calculate and the script will return Baerwald (Lofgren A), Lofgren B and Stevenson geometries for that arm length, along with a plot of tracing distortion. You can also click on the null points of arms in the tonearm database to fill in the form automagically and compare the manufacturers alignment with optimised geometries.

Notable additions to the new calculator include figures for maximum tracing error (in degrees), custom name/length/overhang/offset angle for all plots (enabling comparisons of up to 4 tonearms of different design), presets for inner and outer groove radii and a plot of tracing error (this is the basic angular error data used to calculate the distortion plot).





Error handling has hopefully been much improved on the previous calculator, but the comprehensive rewrite may have introduced new bugs.

If you spot any bugs or layout issues please post here with details, thanks

Regards,
JaS

[JoeE SP9]

Great and thanks JaS! You are going to make this a sticky?

[JoeE SP9]

Sorry! I see you did. Forgive me for doubting you.

[flavio81]

Excellent JaS! Thanks!

[steve195527]

The problem with all these alignment calculators etc is the measurement has to be more precise than most folk can manage at home,I doubt whether anybody can measure as accurately as the commercially available protractors are made to,there are just too many variables

[JaS]

The problem with all these alignment calculators etc is the measurement has to be more precise than most folk can manage at home,I doubt whether anybody can measure as accurately as the commercially available protractors are made to,there are just too many variables

The calculator is more a tool to compare alignments and mounting distances than an aid to alignment itself. For example if you have an arm with unknown measurements you can work back from a measurement of the effective length to find a workable mounting distance, or if your arm that has unusual geometry you could check to see if a commercial protractor with say Baerwald or Lofgren B is likely to work, or if an alternative mounting distance might be worth trying. Which protractor you end up using (DIY/commercial/2-point/arc etc) is an entirely different matter.

Regards,
JaS

[steve195527]

The problem with all these alignment calculators etc is the measurement has to be more precise than most folk can manage at home,I doubt whether anybody can measure as accurately as the commercially available protractors are made to,there are just too many variables

The calculator is more a tool to compare alignments and mounting distances than an aid to alignment itself. For example if you have an arm with unknown measurements you can work back from a measurement of the effective length to find a workable mounting distance, or if your arm that has unusual geometry you could check to see if a commercial protractor with say Baerwald or Lofgren B is likely to work, or if an alternative mounting distance might be worth trying. Which protractor you end up using (DIY/commercial/2-point/arc etc) is an entirely different matter.

Regards,
JaS

knowing the mounting distance etc is ok but even measuring that accurately is very difficult,unless you buy a dedicated arm and use something like a like a linn fitted with a keel sub-chassis(other turntables are available!)then errors always creep in,if anybody has an arm mounted within 1 or 2mm of where they actually think it is on a armboard that is either home made or the mounting point isn't machined in such a way I would be very surprised,even mounting the cartridge can be guess work as we are relying on the cantilever being "dead true" and even the stylus being mounted on that in precise orientation,we all know that a lot of the times even those aren't correct

[JaS]

errors always creep in,if anybody has an arm mounted within 1 or 2mm of where they actually think it is on a armboard that is either home made or the mounting point isn't machined in such a way I would be very surprised

That's one of the reasons I prefer to use a two point protractor. I'm not sure what this has to do with the calculator though

Regards,
JaS

[steve195527]

errors always creep in,if anybody has an arm mounted within 1 or 2mm of where they actually think it is on a armboard that is either home made or the mounting point isn't machined in such a way I would be very surprised

That's one of the reasons I prefer to use a two point protractor. I'm not sure what this has to do with the calculator though

Regards,
JaS

same here,everything is a compromise using a "normal" pivoted arm

[JaS]

same here,everything is a compromise using a "normal" pivoted arm

True, but I'd rather the compromise of a good pivoted arm than those inherent in linear arms - even the good ones are a PITA ergonomically and except for P-mount designs they aren't any easier to align accurately. IMHO that is

Regards,
JaS

[steve195527]

same here,everything is a compromise using a "normal" pivoted arm

True, but I'd rather the compromise of a good pivoted arm than those inherent in linear arms - even the good ones are a PITA ergonomically and except for P-mount designs they aren't any easier to align accurately.

Regards,
JaS

and don't forget most of the linear tracking arms rely on a a slight angular error for their servos to "kick in"!:-when I said normal I meant in comparison with something like what Garrard used to market on their zero100:-didn't like those types either:-too many pivot points for slop to develop with use

[1200y3]

For sure it makes popping an arm on the SP10 much simpler. It is surprising how much "land" there is when placing an arm in the "outer field". I also like to play around with 45s to see how accurate we can get.

[djw.lp]

Note to PL-51 owners, apparently the 221mm effective length for tonearm pivot to
the Hub is incorrect. I measured roughly 204mm on my unit. Also the available
overhang with the Shure V15-III is on the order of 5-10-mm.

I will be arranging a more precise measurement in the future so take with a grain of salt the dimensions on the attached PDFs.

I would appreciate owners of the Pioneer PL-51 repeating these measurements, and I will provide updated protractor(s) for the PL-51 + V15-III combination.

Note also that the Data Base for Tonearms reports Eff Len 236.5mm, which is the
sum of 221 + 15.5mm OH as reported in the user manual.

Cheers Dan

[JaS]

Note to PL-51 owners, apparently the 221mm effective length for tonearm pivot to the Hub is incorrect. I measured roughly 204mm on my unit.

Effective length is not the spindle to pivot distance, it is the distance from the arm pivot to the stylus tip when set to the recommended overhang. According to Pioneer's published specifications for the arm the spindle to pivot distance should be 205.5mm

Regards,
JaS