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Multiple arms, multiple cartridges and geometry?

I have read the debates regarding the benefits of different tonearm geometries......Lofgren A and B, Baerwald, Stevenson etc....and I appreciate the benefits of choosing where, on the vinyl record, one wishes to have the least spread of distortion.
I also have read where certain arms seem to perform better with one or other of these geometries?

I have two turntables with three different arms on each one and I have a total of over twenty five different cartridges.
Four of those arms have removable headshells and twenty of my cartridges are mounted on their own headshells ready for installation into any of those four tonearms.
How then.......can I have different geometries for each arm if I don't wish to re-align a cartridge within its headshell depending on the arm in which its installed?
Surely......I must select a single geometry for all my arms so that the cartridges fixed to their headshells....are truly interchangeable?
128x128halcro
lewm
13,019 posts
 
"...you mean that when I set up a cartridge on one arm with, say.....Baerwald geometry......it doesn't mean that it will be correct if I change to another arm with a different pivot to spindle distance and overhang?"

Yes; it will not be correct. But your tonearms are vintage Japanese types. Many or most of those were designed with Stevenson geometry in mind or with some idiosyncratic geometry unique to that tonearm (e.g., SAEC 308SX). You can use Baerwald alignment for some of them (not SAEC 308SX), if you must, but the cartridge will end up twisted with respect to the long axis of the headshell. My experiments with doing that did not sound good. But no matter what geometry you use, a given alignment of the cartridge will work in two different tonearms only if they have the exact same P2S distance, effective length, headshell offset angle.
mapman's avatar
mapman
22,182 posts
 
How about using a standard alignment template, whichever one might be best for your table, similar to the user printable one that Linn has provided for the Axis specifically, and just applying it as needed?

That has always worked for me with the Linn Axis in terms of getting hard to fault sound quality, ie faultless tracking, good dynamics, quiet background, and no sibilance, which are usually 4 very good indicators that things are working well.

I have never swapped arms, but if the template could not work, that would tell me the arm is not a match to the table.

Why make these things more complicated than need be?
lewm
13,019 posts
 
Dear Mapman,
Your alignment template works for your tonearm. It's specific to the Linn tonearm. I cannot imagine how to design a "standard template" that is turntable specific. The turntable does not give a rat's butt what tonearm is mounted on it, so long as the tonearm will fit on the mounting platform. I don't think off the top of my head that there is any way to escape the necessity of re-aligning each cartridge for each tonearm, unless the two tonearms have identical length parameters and headshell offset angle.

But, Halcro, I just remembered that you do use outboard arm pods that can be moved around freely wrt your TT101. This gives you more degrees of freedom wrt P2S distance, but won't completely obviate the need for tonearm-specific alignment.
nandric's avatar
nandric
4,086 posts
 
Dear Henry, You need, it seems, to start a new. I hope that
you own no more then 400 Lp's so you can rearange them according to the distance of the outer groove to the spindle. Assuming 3 geometries you will have then 3 kinds
of LP's collections which is 3x more then we, the other, have because we own just one collection. Then you should mark all your tonearms according to the new ranking or geometry while the same should be done with the carts/headshell combos. This way you will have 3 kinds of every kind while thanks to the markings no confusion
will ever (more) occur.

Regards,
halcro's avatar
halcro OP
2,664 posts
 
Dear Nikola,
Que??.........
Lew.......you're right about my ability to 'massage' the spindle to pivot distances for all my arms.
I'm thinking......and I may be wrong (need to check the Vinyl Engine formula)....... Whether I can adjust the P to S dimension of all the arms to have a uniform 'overhang' dimension?
Will that allow for a 'common' interchangeability?
Regards
Henry
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