Am I totally nuts or just a bit off?

Good mono recordings are also very useful as a reference standard to help get things set up well for stereo. If you get a solid and full nicely centered and focused image with good mono recordings, chances are the speaker setup will be pretty well optimized for stereo at that point as well. Its much harder to use stereo recordings as a reference in that there is so much variability in how the stereo channels are utilized from recording to recording.

Truth be told I don't even know what a um is,all I ever studied was history.

:-)

"um" = "micro-meter" aka "micron" = 1 millionth of a meter = 1 millionth of about 39.37 inches.

"mil" = thousandth of an inch.

15 um = 0.00059 inches = about 0.0006 inches = 0.6 mils, as Viridian indicated.

Regards,
-- Al

Viridian- I played 3 records that have been in heavy rotation(oh, that Dakota Satanton)the sound is much fuller and with more detail, must be getting all of that groove!
I did't notice any damage, just less surface noise.

That whole 91ED family must be the greatest buy of all-time in audio.First real table I ever bought was an AR XA that came with one. 45 TT's and twice as many carts later I should have just stopped there, have just as good sound and I'd be 30K richer .

Al, thanks for the class, even at age 78 I got a lot to learn LOL.

Imagine: If the internet had been around in the late 50s everyone would have been discussing how stereo and Solid State was ruining HiFi and young people- a conspiracy by music shops to make us buy two of everything.
I had an Uncle that was into HiFi. That must be how I was influenced during my formative years... He had a stereo console in the 60s and moved up to a Pioneer Quadraphonic receiver in the 70s with a Dual tt. So extrapolating speaker count from a single in the 50s to two speakers in the 60s and 4 speakers in the 70s, we should be up to 64 speaker systems today. Let's see, if my uncle were still alive today, I could show him my 7.1HT system that is mostly for the kids. Hey, that HT system has 20 drivers when I add them all up. I guess the speaker marketing guru's have been pretty successful after all over the decades.