Is extremely accurate "VTA" adjustment necessary?

Decay, how thick are those spacer record mats that you add for thin LP's?
This does seem a like good option, since you are not disturbing the mechanical aspects of the arm mounting. However, like many popular tables mine does not use any record mats, which makes this impossible for me.

(sorry for adding another answer to the thread hear, I should learn to answer everybody in a single response..(:-)

Rene

Restock, I appreciate your intellectual curiosity about this issue, but it strikes me that you are asking but not accepting the sharing of experiences you are receiving. I can tell you only what my ears tell me while listening to my system.

Doug Deacon's experience matches my own exactly. We approach our solutions to this somewhat differently, but we we share the same experience, we are hearing the same things, and we both adjust VTA on an LP-by-LP basis. In my case, I have settings marked that are ballpark correct for "most" 120 and 180 gram records, and which I have carefully selected based on the interplay of VTA and VTF on my tonearm (each affects the other). I start at that applicable ballpark setting for the given LP (or slightly off from it if the record is 150 gram or 200 gram, based on experience). I then will adjust by ear if things are not sounding right: if it doesn't sound dialed-in, I simply stop the record, make a VTA adjustment, and start up again. My tonearm allows for very minor adjustments (in the .001" range and continuously adjustable), and even very small changes in this sub-.005" range can, on some LPs, make a difference in whether everything locks into place or not. I have experienced the sonic improvements such minor adjustments can make, my listening partner spouse has experienced it, my audio friends listening on my system have experienced it, and the manufacturer of my turntable experiences it. We've done it numerous times in our listening sessions together.

I try not to get compulsive about VTA - after all, this is about enjoying the music! - but I do pay attention to it and often I notice that when I'm simply not as engaged in the music, often the VTA is slightly off.

I will also add that, in my system, the answer to why such minor VTA changes are audible is not an artifact of mechanical stability variables as you hypothesized could be the case. My tonearm (Walker Proscenium) is not adjustable on the fly for exactly those types of concerns. Locking rings and a set screw bring the toneam to a mechanically rigid state after adjustment, and must be loosened to make any adjustment; nevertheless, it only takes 10 seconds to make an adjustment.

Your question, however, was is such extreme accuracy "NECESSARY." My answer to that specific question is: in my system, yes, it truly makes a difference and I hear it. I don't always bother with it and still enjoy the music, but to get the maximum quality of playback that the system can deliver, it is absolutely necessary to pay attention at these minute degrees of difference. And, I don't always do it because sometimes I'm not being that pickly; sometimes FM radio is OK, but most times I'm looking for more - especially in my listening room.

......

Speaking of which, I've just come back to edit my post to share this experience after writing the above: As I was finishing the post, I was being troubled by the piano reproduction on a Philips LP of the Beethoven Cello Sonatas with Rostropovich and Richter that was playing as I was writing (Philips 835 182/83). The piano sound was "shattering" slightly on some strongly struck notes in some louder passages at the end of the last movement. I changed the VTA by possibly .002" (two-thousandths of an inch), relocked the arm and replayed the section. The "shattering' was gone and the notes were reproduced in their full clarity and dynamic.
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How about this for a practical answer? If you are debating whether to spend $200 to allow EASY and REPEATABLE VTA adjustment and you think that you will be adjusting VTA on an even occasional basis, buy it!

Rene, I think you are right on target with your question as I see you just stating it:

Why don't we hear the variation in VTA as the LP rotates, since this variation is much bigger than changing the armheight by .005'

For some turntables, the geometries are such that the variations over the playing surface of the record can and do simply swamp efforts to be hyper-critical in setting VTA (and azimuth and VTF for that matter). Design and execution can allow arms to vary in height across the surface of the record, platters may not be flat, records may not sit flat against the surface of the platter (for a host of reasons), etc., etc. All of these will do exactly as you describe: create VTA changes that are far greater in magnitude than the adjustments Doug Deacon and I are talking about. You are correct to question this.

For example: For many years I owned and enjoyed an ET II tonearm. For all its many virtues, however, the implementation of its design allowed the arm to sag by as much as .006" from one end of its travel across the record to the other. The resulting change in VTA was clearly audible as the tonearm traveled across the LP. You could either have it exactly right at the center, or at the outside edge or in the middle, but not all the way across the LP. The result, with some cartridges, was an audible shift of soundstage as the cartridge tracked across the record, with some shift in tonality as well. My solution was to use a Grado Reference cartridge in the arm which was less fussy about critical VTA and enjoy the other virtues of the arm.

With my turntable today, and I can only speak to my turntable, it's a whole different situation. My turntable today is a Walker Proscenium, and this turntable has no variations of geometry across the LP playing surface. Given your interest and your background and training, I thought some technical information would be interesting to you, so I called Lloyd Walker to get some specific data on various measurements:

Platter: a 70lb lead platter machined flat to within "one-half of one-ten-thousandths of inch" across the entire platter surface.

Platter diameter: smaller than the lead-in grooves of the LP so the raised lip of the outer edge is OFF the platter; label area deeply recessed and larger than the label. Result is that the playing surface of the record lies perfectly flat on the platter.

LP Clamp: pulls the LP firmly down onto the surface of the platter so the LP is in continuous contact with the platter across it's entire playing surface.

Platter Bearing: Air bearing that maintains the surface of platter in a perfectly flat horizontal plane - their is no spindle so no spindle play, only a centering pin.

Tonearm: Air bearing tonearm that maintains a tolerance of "one-half of one-thousandths of inch" variance in height to the platter across it's entire travel. Rigid VTA and azimuth lockdowns to eliminate any structure flexibility or play. The set up time for the tonearm at the factory to achieve these tolerances typically takes about 2-hours.

VTA adjustment: Rigid and locked during play. Allows for continuous adjustment in amounts as small as "one-half of one-thousandths of inch" - 0.0005".

People sometimes wonder why a Walker Proscenium turntable is so expensive. It's expensive because it's built to these incredible tolerances. (Lloyd says the tolerances he demands are unique.) And those build tolerances are reflected in the incredible playback resolution this turntable delivers. This is the reason that, for me, VTA adjustments are not swamped by other aspects of the LP spinning on the turntable: that LP is spinning as virtually flat as is possible to achieve.

Hope you've found the technical data interesting. I did as Lloyd explained it to me.

With regards,
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