Thoughts on VTA......

OP:
"I have read countless posts where members are spending hours on exacting setup of their VTA with varying levels of tools.

Then there is another camp who set by ear.

My thoughts/questions on this subject arise from vinyl thickness difference.

Surely going from a flimsy flier early 70,s vinyl to a later 180 or even 200gm issue is going to change that painstakingly set VTA considerably.

So thoughts rattling round is why go to all that trouble when it IS going to change depending on the vinyl played?

To my mind it would appear that one of the arms that includes on the fly VTA adjustment would be the answer.

Your opinions or suggestions?"

MF has some good comments on this in turntable setup videos you can find on YouTube. 

In my case, I learned what effect VTA has on sound when setting up my first Benz Glider. I kept lowering and lowering, it kept sounding better and better..... until it didn't. I went back up a little. Better. Went up and down in smaller and smaller increments until I was satisfied. This was with the Graham arm. "Small" increments came down to interpolating within the smallest marks on the Graham adjuster. The width of one of his marking lines, if I remember correctly. Seemed crazy at first, but I kept at it until I was sure. The most time was spent not adjusting, but confirming what was in hindsight pretty obvious from the start.

Years later I went through this same process with my Origin Live Conqueror arm and Ruby H. Then again last week with my Koetsu. I can zero in really fast now but its always the same deal, the tweaks between records are really tiny fractions of a turn.

Now if you do the math, threads per inch, fractions of a turn, its clear VTA adjustments of much less than a hundredth of an inch are audible. That's why VTA absolutely must be set by ear. 

Unless, of course, the difference either does not matter to you or you can't hear it. In that case then, why bother?

In my case, it takes me nearly no time at all to tweak VTA and write it down. One album side, couple tweaks, max. Write it down. One and done.

Even then there are still times when I put one on and it sounds so good I just enjoy it, no tweaks. In that case I just write down whatever VTA was. So I can repeat it. And that's that. Because for me that is the whole point, to enjoy the music. Whether or not someone else can appreciate it, or how much time they spend tweaking, simply is not a factor.

On a 9” arm you need to raise or lower the arm pivot point by 4mm to change SRA by 1 degree. 
Mike Fremer says he sets his with an average record and leaves it alone since the thickness variance causes changes in small fractions of a degree.

Why not just use platter mattes with different thicknesses? I have several I’ve cobbled together. Seems to work fine for me. 

I have 6 "high end" matts for just that reason voice .Just stack 'em up !

@cleeds  You note:  "Of course, the overhang will remain constant if you are able to precisely adjust arm height to compensate for various thicknesses of LPs. But if you are adjusting VTA by ear on the fly, what determines to your ear that you've reached the ideal arm height?"  

I know when I hear it and it is clearly audible, even to the untrained ear.  To paraphrase Bill Nelson, it "makes the music magic, makes the strings ring like bells in the night."  Cymbals and bells ring with that natural tone you hear at a concert, horns blow your hair back, the right vocal tone sends chills down your spine, you can hear bass strings vibrate against the fingerboard and feel organ pedals compress your guts.  Get the arm a bit too high, strings and horns go shrill.  Get it a bit too low and you lose definition.

Further:  "Is it achieving the perfect VTA? Or is it achieving the perfect overhang?"

I would suggest that it is probably VTA.  I say this because there are several alignment schemes that can be used, and more elaborate protractors like the Feickert allow users to select which one they might prefer.  There is no absolute right answer.  Get VTA wrong though, and you can immediately hear it.  Considering those two points and knowing how sensitive my VTA OTF arms are to changes in height leads me to feel that overhang and VTF are perhaps less critical than VTA and azimuth.  This is probably due to the minuscule contact area between the stylus edge and the groove.  It has to be in close proximity to angle at which the record was cut to get all the information out.  A bit of skew to one side or the other might have a slight effect on image, but can't say about how significant that might actually be.

Other experiences seem to support this.  A lifetime of playing warped vinyl until I found the Vinyl Flat is one.  If I got the VTA right on a track that was essentially flat, everything went awry as soon as I hit the warped area.  Very irritating.  My second table is a 70s vintage Pioneer with an S arm and fixed VTA.  It's reserved for less than pristine vinyl and recordings that can't benefit from better transcription.  I put as precise an alignment on it as I could manage without investing more than a few bucks and if I drop a thicker record that was made in the early 60s, one of the dynaflex flimsies or one of the newer 180 gram pressings on it, it sounds awful.  Harsh and brash when too thin and muddy and indistinct when too thick. Put on some Who or Floyd pressed in the era it was made and it's up to the task.

I've also fiddled around with VTF on the Pioneer to see what there was to hear.  I have a very repeatable digital scale that resolves to hundredths of a gram and has a tolerance of + or - 0.02 g, so it's a simple matter for me.  The factory recommended 1.8 grams for the Ortofon 2M Red is indistinguishable from 1.7 or 1.9 to my ear.  That's about 5.5% of range, and a greater percentage of tolerance than that for either VTA or overhang adjustment.  Accordingly, worrying over minute changes in overhang or VTF that could potentially occur from adjusting VTA OTF seems fruitless.

Some über-wealthy vinyl geek may set up a laser interferometer to finally resolve all the mathematical particulars, but I've found the solution that works well enough for me.  It's easy, fast, reliable and makes my world a happier place because the music sounds so much better.  And that's really what this hobby is all about.