Azimuth 2020

Unwarranted to disagree with anyone here. Civil discussions are pleasant AND educational. Thanks all for the insight.

you can not use a pocket mirror for azimuth.  The silver (reflective) side is above the glass its sitting on which will create big errors.   If you must use a mirror, get an old SLR camera mirror that is silvered on the correct side for your application.

Fuzztone,  I find it's most enlightening when two or more people openly disagree and then have a civil discussion, preferably backed up by facts in support of one position or another.  It's fine to disagree, in my opinion.  It's better not to be nasty about it.
Stringreen, I did not want to be needlessly contentious with Mijostyn and others who have suggested using a mirror.  I personally do not.  Also, I never finished explaining my rationale for deciding not to agonize over determining azimuth electrically vs setting it "physically", by setting the stylus square in the LP groove.  It's because in the electrical measure, if the stylus ends up at an angle with respect to 90 degrees azimuth, then you may (or may not, if you haven't done it correctly) have better numbers for crosstalk, but you have introduced other sources for distortion and possibly sources of wear on the stylus, suspension, and the LP.  That scares me more than a small deviation from the best possible numbers for crosstalk.  If the cartridge is poorly constructed such that the azimuth angle has to be other than 90, send it back.  (I've never tried to do that, because I never had the foresight to measure a brand new cartridge just after receiving it.  Also, most of  the cartridges I own are vintage.)

https://www.analogplanet.com/content/crazy-little-thing-called-azimuth-part-2

I use the Tacet Vinyl Check record, get my multimeter out and drive everyone around me crazy with the noise...

With respect to some who are well-known experts here, I don’t agree with much of the above. Except Lewm.

Peter Lederman of SoundSmith gives a very good discussion of this topic. My interpretation and memory of what he said, follows. Hope I got it right - you can check it.

He points out that crosstalk is partially a measure of how well the stylus sits in the groove, and that high end cartridges can have very different left and right crosstalk figures. He points out that it is better to have high thirties in one channel and low forties in the other, rather than high thirties in both. And that high end manufacturers do that.

My higher end Koetsu had to be canted at a terrible angle to achieve equality at 38 dB (Foz). An electron microscope photomicrograph showed that the stylus was perfectly symmetrical, so that was not the issue. The issue was, obviously, that Peter was right, and equalizing crosstalk was a big mistake for high end cartridges.

So I start visually by assuming that a high end cartridge isn’t too far off, and adjusting by ear. It’s not as fast or easy or repeatable, but after many small adjustments over a month, it’s pretty damned accurate.

That’s judged subjectively by how well the stylus sits in the groove and pleases the ear, as well as objectively by near perfectly symmetrical wear patterns on the stylus (photomicrograph).

My $0.02. YMMV