DaVinci tonearm and azymuth

Lewm is right. Correct azimuth is in the very first an optimized geometrical position of the polished areas (NOT the mere stylus...) of your stylus vis-a-vis the two walls of the record groove. Lets further assume, that hardly any cartridge on earth is blessed with two identical coils giving identical output millivolts. This leads to the cruel thought that "optimizing" the electrical figure "crosstalk", without determining the individual electrical output of each coil first, might not necessary give the geometrical correct position.
As tempting as computer-analysis may be (and we all (me too...) are long used to computer-generated convenience in many respects of our everyday life .... and even more to come..), it does not necessary give the correct result in adjusting phono cartridge azimuth on a electrical basis.
Here once again we have to "walk the distance" and should by all means trust that biological yet fairly complex device inside our brain - the hearing.
Take a purely acoustical recording - old Opus3 records do work marvels here... - with a solo voice accompanied by solo instrument with resonance corpus (a guitar, bass, piano - you name it).
You will hear it when azimuth locks in.

Dear Dougdeacon, - nice link. It works very well indeed. It does not cure the cancer either, but it surely will prolong life and restore its level ( of performance ) into the high 90 percentage.

.. trust that biological yet fairly complex device inside our brain - the hearing.

The Danger Zone

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For clarity, I think we all agree that shimming is sub-optimal. The method Thom and I described and the link I posted are a band-aid for a problem that shouldn't exist, at least not on pricey tonearms. Shimming works for azimuth but it also has sonic side effects in at least two areas:

MOUNTING RIGIDITY
The more rigid the coupling between cartridge and headshell, the more accurately cantilever movements are translated into electrical signals. Looseness in the cartridge mount slurs transient responses, reduces amplitudes, adds overhang to every note and raises the sound floor - slop, slop, slop.

The solution is self-evident: if you must shim for azimuth, use a rigid, non-compliant material.

ENERGY TRANSMISSION
As Larryi already described.

The precise sonic effects of altering energy transmission between cartridge and headshell will vary with individual components. Nevertheless, inserting two new material interfaces increases the frequencies that will be reflected back into the cartridge. That necessarily raises the sound floor.

Shimming's a reasonable band-aid, that's all.

And what Syntax posted! ;-)

The Danger Zone... so true... arrggghhh!

Interesting about shimming because Yip of the Mint LP Tractor has the following in his "best tips for customers (down the page a bit):

http://mintlp.com/best/bestips.htm

:) listening,

Ed