Record mats, VTA, clamps and my ears


Hi-
I've got a Thorens TD 316 with ClearAudio Arum Beta+. I've been experimenting with the original mat, a slightly thicker Audioquest Sorbothane mat, and a thinner Ringmat. I have dutifully ignored reading too much about VTA because my 'table doesn't support adjusting VTA.

The Sorbothane sounds better than the stock. Highs are the same, but the bass is less muddy. The Ringmat has a similar improvement in the bass, but there is more high end air. There is also very slightly more high frequency tics. But the problem is that some recordings sound thin. Airy, sure. But thin.

The turntable was set up using the original mat by a respected area tech. Not the very best high end guy--I would have been out another $200 had I used him. (The joys of the big city). Still, I'm confident my tech did a creditable job.

So I'm wondering how much of the differences I'm hearing are due to the change in angle of the stylus in the groove due to the different mat heights, and how much is due to the quality of the interaction between the 'table and the mat.
Are my findings consistent with advanced stylus angle theory? Should I have been paying attention in class when Sam T. told us everything I should already know?

Also, being The CheapSkate, I have a "The Original Pod Disclamp." Got it for twenny bucks on eBay. Anybody ever heard of this animal? Alas, I have questions. The Pod Disclamp worked best with the original mat insofar as the original mat is the stiffest. This is important as there is a depression around the spindle, so it physically possible to push the center of the record near the spindle down far enough so that the perimeter of the record raises up. No matter--even with the needle going up and down, things SOUND better that way! Arrgh! What does this mean? Must I now pay $2000 for a Final Tool just so I can own a 'table that follows the basic laws of physics?

Anyway, I try to apply just enough clamping force so the record is somewhat damped, yet not contorted.

The clamps effectiveness is reduced with the corresponding lack of stiffness of the mat. At least that's what my wife keeps telling me. So the clamp works best with the original mat, second best with the Audioquest Sorbothane, and third best (but still an improvement) with the Ringmat.

Hopefully, my confusion hasn't dulled your enthusiasm over providing me with my much lacked and sorely needed guidance.

I remain--

The Cheapskate
brtritch
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.
Thank you all for your comments. It's so nice to find like minded individuals that write extremely graphically explicit technically confusing sentences that need to be read a half dozen times!

An interesting side note: I had been using a tweaked out Fisher 800C receiver (1960's top of the line, best all tube receiver ever made) until two days ago, when I subbed a CJ PV-5 tube Preamp into the system (still using the Fishers 32 RMS per amp section.)

The most profound differences were in gain and bass response, which in turn wrecked havoc with my turntable. I had had 2 five-pound lead weights on two corners of the chassis. They were a desirable tweak, until the newfound gain and bass response caused impending subwoofer meltdown. I’m sure most of you can imagine the cycle: a little rumble causes unwanted bass response, which causes vibrations, which in turn cause more rumble.

Removing the weights, I experimented with the three different mats and clamping and unclamping, adjusting to produce the loudest bass I could play without overload using B. B. King’s “You’re Mean” off the “Completely Well” album. The sorbothane mat with clamp won.

I experimented with cones up, down, rubber, and sorbothane hemispheres in various combinations on my Target turntable rack. The best combination occurred with a Vibrapod shaped piece of rubber (marketed to be used to mount machinery for vibration control) directly on the Target MDF, with a Black Diamond cone pointing upward on top of it, with the Thorens mounted on top of three of those rubber/cone doohickeys. I’m not done tweaking (could God build a system so good that even he couldn’t tweak it?), but at 106 dB I think the stabilization is mostly taken care of.

With regards to the writer that wrote that the Pod DisClamp should never be used, I’m a big guy—6-3—with big hands. The trick is to support the platter with the fingertips while using the thumbs to engage the clamp. A trip to the hardware store suggested by another writer produced an assortment of washers, including a very flat one just smaller than a record label that I glued some felt to that compensates very well for the otherwise relatively uneven downward force cause by the three prongs of the clamp.

The Cheapskate loved how the 69cent Vibrapod shaped piece of rubber outperformed the $60 Audioquest Sorbothane hemispheres, as well as the assortment of washers I got for 82 cents.

Keep those cards and letters coming,
The CheapSkate
I love your tweeky method of overcoming the shortcomings of the Pod. Great work. That's what the hobby is all about.
Basement, thanks for kicking me in the head and knocking some sense into me. Sometimes i tend to look at things as trying to set them up for optimum performance and forget that not all components / installations are up to the task. As such, i need to remember to take the specific components being used into account. This is not to say that the Thoren's is not capable of working quite reasonably, but to say that i might have been giving it a bit more credit than it deserved and taking things for granted.

I think that Brtritch found out the limitations of his installation the hard way i.e. running into problems with acoustic feedback, etc... When you start getting into high SPL's and have the capability of low bass with great authority, you really have to work on your TT installation. Luckily, it appears that Brtritch has found a suitable solution for not that much money. Too bad all of our problems aren't that easily solved : ) Sean
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