Is extremely accurate "VTA" adjustment necessary?

A lot will depend on the contour or your stylus - how sensitive it is to groove tracing - and how resolving your system is. Some cartridges (and some systems) simply are not that sensitive to modest VTA changes. Others are highly sensitive and spending the time to make those adjustments can be incrediby impactful on the sonic quality of the playback. In my system, I can make seemingly minute changes (as in thousandths of an inch) and it can make all the difference on certain (but not all) LPs. On a previous turntable with different cartridge, small changed were not so impactful for me. Today they are (and my system today is also much more resolving and musically satisfying, I would not willingly go back).

See my post from just a month ago:
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1094417113
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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.

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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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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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Raul,
I have read many of Doug Deacon's posts over many months (both here and on Audio Asylum) and I consistently find them independent, thoughtful, based solidly in his own experience and listening tests, and quite well reasoned. I think you have very inappropriately "slammed" him in your comments. You and Doug have disagreed a number of times; that is no reason to make this personal attack which I find both unwarranted and offensive.
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Gregadd, for VTA I suppose I'm in the adjust by ear camp (but not by eye!). For azimuth, I totally agree with you about using some additional mechanical/electical aid to the process.

For setting both VTA and VTF, I've learned from Lloyd Walker's approach, and I find that, with an appropriately designed tonearm that gives one a way to make highly controlled micro-adjustments to the VTA, doing it by ear is the only way to get done well. (Trying to insert shims would be the death of me, though. :-) )

Here is Walker's explanation of the fine tuning process for any who have an interest:
http://www.walkeraudio.com/fine_tuning_your_turntable.htm
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Good, as far as it goes. The challenge is the inconsistency with which records have been mastered over the years. As has been commented on already in this thread (Doug, I think) a standard was not adopted until later on in the LP era and even then not all mastering engineers rigorously followed the standard. So you have cutting angles anywhere from 20 degrees to 23 degrees, and thus variation from some LPs to other LPs even though they are the same thickness.
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Gregadd, I think the last 6 sentences of your post make a very fair statement of reality for VTA, particularly:

You can't ignore it but you don't need to worship its altar.

Best regards,

LOL: "(okay!okay! adjust the koetsu for proper vta. by ear if you like)"

Thank you for the humor, Gregadd!
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As a point of interest given this extended discussion, 6moons.com just published a review of the Walker Proscenium turntable and an interview with Lloyd Walker. One of Lloyd's comments was about his design conclusions on adjustable VTA during play:

Lloyd Walker: One thing we discovered right away is that adjustable VTA during play is probably one of the worst things you could ever put on a tone arm.

Reviewer: Why? I loved it on the Graham arm and it spoiled me. The ability to adjust VTA while playing is certainly convenient.

Walker: Well if you notice, when you adjust some arms while they're playing and you run the adjustment up and down from top to bottom over the whole range, you'll notice some differences but it's not huge. You change the butt of the VTA on our table 1/1000th of an inch and you can hear it plain as day. It's enormous but every time you set the VTA, it's locked in place. The arm cannot flex or move. To adjust an arm during play, something has to be left loose so the arm itself is wobbly. When you're talking about trying to read information in a groove that operates down into the micron size, iron-clad stability is critical. If you leave an arm loose enough for VTA adjustment during play, it will flex and you will lose dynamics, information etc. You just give up too much music for a few minutes of convenience.

Reviewer: But other arms which have adjustable VTA during play have tight locking mechanisms.

Walker: Doesn't matter. When you lock it back down, it's gonna move because that lock's going to torque it to one side and that's not only going to slightly change the VTA but it'll shift the azimuth as well since the whole assembly is flexing to one side.

http://www.6moons.com/audioreviews/walker4/sota_5.html
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