Record mats, VTA, clamps and my ears

No, the VPI TNT is a very heavy TT (the platter alone must weigh 10 lbs) and is not "supposed " to benefit from a Ringmat. That's why I was so surprised.

Dave, i can see what you mean about these tables being pretty heavy. Thanks for helping me to realize that. I checked things out at Audio Advisor after reading your post and all of the VPI's there appear to be pretty stout. I'll have to ask my friend what model VPI it was that UPS obliterated. Sean
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VPI's platters at the upper end of the product line are at least 20 pounds or more (acrylic / lead / cork combo) & yes I've been told that they are reported to work best with the record very closely coupled to the platter. Mine (a MK4 with a TNT bearing & platter) is supposedly that way. I'm not going to claim firsthand experience here, but the guy that I bought it from has. He had experimented extensively with mats & clamps, ending up with a paper thin "analog survival kit" mat & the Black Diamond clamp. Not wanting to 'reinvent the wheel' I've never tried anything else, but after the above read-through I'm tempted to begin experimenting all over again. Not that I'm unhappy with the rig as-is, in fact quite the contrary. Sometimes, ignorance really is bliss.

Do not ever use The Pod disc clamp. It requires you to put downward pressure onto the spindle and can damage the main bearing. The three feet can also cause a degree of deformation of the vinyl, but this is less severe than the former problem. Modern clamps such as the SOTA, Michell, etc. avoid both of these problems in various ways. Don't cheap out when your precious vinyl and turntable are at stake! The real theoretical advantage of using the Ringmat is that bearing noise and platter/plinth borne vibrations are not easily transferred to the disc itself. The drawbacks have already been mentioned.
Marty

Mr. cheapskate;
If the difference is a 16th of an inch or more, I would tend to think that you would hear a difference because of vta. I haven't heard the arum beta, I'm also not sure of its stylas shape, but if you are critically listening to the differences in these mats, and are hearing the differences, I don't see why you wouldn't hear a difference in vta.
One thing that leads me to believe this is that I have generally found that aq mat to sound more on the dark side. although if it's taller, that would tend to make the bass less defined,sometimes I find the bass to get more defined when I get into the best spot, as opposed to vta to high in the back. Also, the lower ringmat and the sound you describe would support this.
But, the differences you describe also support what I hear are the differences in these mats.
So the only way you can find out, is to find out. to keep track of vta, I take a business card, set the stylas down on the inner groove of a record, and mark on the business card the top of the tonearm at the farthest point forward and at the farthest point back at the lead-in groove. Genarally, most cartridges will be about 1-2 millameters down at the back, which will translate to about 1/8th of an inch at the base of the arm.
You could also try different combos of mats to try to keep all the heights the same, if for nothing else an experiment in finding the ideal vta.
Finally, anther point is that your average repair shop will not make concessions for vta if your turntable/arm doesn't support it. So evan if he did a respectable job, your vta could be way off. If you find that so, you could find where you want it and take steps to put it there.
And finally again, while I agree with you sean, I disagree. Your theories are sound, and they are true, and your knowledge is high, so is the quality of your analog replay system. This is a thoerens. While it is better to have a disk solidly anchored to avoid resonences, you have to consider what you are anchoring it to. If resonences reflect, that can be worse, and what will be more effective in controlling them will have as much to do with the nature of the resonance as much as the attenuation of such, nature being the particular frequencies and the reaction of how they are coming about. The fingmat, for instance, is not really meant to be a flimsy way to float the record above the platter, but rather is desighned to solidly anchor the disk while isolating it from the platter, (cork is stiffer than rubber), while at the same time, supplying resonence control by virtue of the distance of the rings. If you had a linn, or a theorens, how would you couple the record to the steel?
And finally once again finally, there is nothing wrong with tweeking around with that thereons. Its just as fun in my book to tweek out a less expensive turntable as it is any. And the results could be more impressive.