Geometry for pivot tonearms - calculation errors??

Dear John: Good to see your links, by coincidence ( in other thread: http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1235522919&openflup&82&4#82 ) I posted your first link ( calculator ) that is very useful.

Well, this is an interesting one too:

http://www.vinylengine.com/phpBB2/viewtopic.php?t=4854

Through these links and many others almost all of us can/could make and try different " options " on the subject and decide which " distortions " likes more to each one of us or which " distortions " match our music/sound quality performance reproduction in our home audio systems. Even we can create " new " tonearm geometry equations.

Dertonarm, about your questions there are different answers depending on the approach you take, in my case I don't want to " invent " something new but to optimize what we have already in hand.
Something that I learn through the time ( experiences ) and through our self tonearm design is that each time you change the effective length ( by changing the overhang or changing the pivot to spindle distance, etc, etc ) we change the tracking distortions/tracking error.
In a pivot tonearm we can't to be at cero tracking error so IMHO what we have to look for is the best way ( best trade-offs for each one of us ) to put at minimum.

As you point out this is a very complex subject and where ( till today, at least I don't know it ) there is no perfect whole answer.
We have to take in count other very important subjects on the tonearm-cartridge set-up where any deviation on any of those set-up parameters degrade or invalidate our " perfect " efforts.

The analog medium is totally imperfect input to output and the best we can do is try to put at minimum every kind of distortions from " everywhere " source and certainly the tonearm audio item is a critical link in this analog audio chain.

Regards and enjoy the music.
Raul.

Dear Johnbrown, thanks for the input.
A good start for this thread.
And the above mentioned links are useful indeed.

However - this is all included in the G.F.Dennes Tonearm Analysis and Summary. These are all about the different options in calculating the arc and the position of the 2 zero-points (together with the maxima and minima of the derivation from the zero-track of course).

I nevertheless got the impression during several threads the past weeks that the BASIC tonearm geometry (all the mentioned links are dealing mostly NOT with the basic geometry, but with the alignment of the stylus) is indeed hardly discussed at all.

Otherwise there wouldn't be that much irritation and confusion about the basic geometry of the tonearm itself - mainly spindle - pivot mounting distance and its ealtions to effective length, offset and overhang.

Baerwald, Stevenson, Bauer, Loefgren - this is all about the aligment of the stylus and the different options of the tracking arc over the LP grooved area.

This is not dealing with the basic geometry of a given tonearm but with its geometrical interaction with the mounted cartridge.

Dear Raul, I agree with you - this is a complex subject. What I am aiming here is the difference between the basic tonearm geometry (for the individual tonearm) and the geometry for the interaction with a stylus (Baerwald, Loefgren, Bauer, Stevenson etc etc.).

I would like to have some light here that there are 2 tonearm geometries - NOT one. We need to fix the 1st - then proceed with any of the mentioned options in the 2nd geometry calculation.

Its this basic TONEARM-geometry I am target on.

Raul-thanks, and maybe all the info and links I presented-*in one post*-will help others to start studying the issue.

Dertonarm-Well, for me-I'm no math wizard-the combination of the JE and CH programs allow me to take alignment theory as far as I want to go. When you've got one program that will allow you to manipulate any of the parameters of the pivot-arm geometry, display the null points in graph form, and then show the percentage of distortion of the stylus through that arc, and *then* use the CH program to immediately print out a protractor that displays that alignment-that's as far as I can go. I'll leave it to others smarter than I to come up with 'new' interpretations and methodology for tracing a pivot stylus over an LP. Saying that, I'll keep reading this thread and to see at what you arrive. (-:

Dear Dertonarm: Could you share your " finds " /thoughts n that 1st geometry for we can understand and try to help about?, because both have an intimate relationship.

Regards and enjoy the music.
Raul.