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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

Showing 3 responses by lewm

lewm
12,433 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.
lewm
12,433 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.
lewm
12,433 posts
 
My opinion is that if you care about really precise alignment according to any single one of the standard geometries (you pick), and given that your tonearms all have different recommended P2S, effective length, headshell offset (which may or may not be true, but from your system photos it looks to be true), this cannot be done. "This" is defined as mounting each cartridge in a headshell such that any headshell/cartridge can be used with any of your tonearms without further tonearm-specific adjustment to achieve proper alignment.
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