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
While it may not seem like it, i always encourage "contrasting points of view". That is why i said "let the fireworks begin" : ) If everybody felt the same way or did the same things, there would be no need for forums like this as we could not learn from each other.

To respond directly to Dave's ( Dopogue ) comments, my findings are based on the following observations. By posting these, i hope to clarify why i've made the statements that i did and help some of you better understand why / how i arrived at these conclusions:

1) you MIGHT reduce surface noise on discs using a non-supportive mat due to the fact that the record is not uniformly flat or evenly supported. The stylus is actually riding higher in the groove and is therefore not picking up the "gunk" that is ground down into the groove. While this might seem like an initial benefit, read on.

2) The problem with this is that you now have accelerated side wall wear on the discs and have increased uneven wear on the stylus since it is no longer centered down into the groove.

3) Since the stylus is no longer centered and riding as deeply in the groove as it should be, you now have less distinct left / right imagery. Bass impact is also reduced since the stylus is no longer fully modulated by the entire depth of the groove. If you have a pivoted arm, anti-skating is also affected in a negative manner.

4) The reduction in direct deep groove contact with the stylus reduces dynamic range. Since the stylus is not "pushed" or "modulated" as hard on louder passages since it is riding only the upper surface of the groove, there is less variance from the quiet to loud passages and dynamic range is reduced.

5) Since the stylus is no longer seated firmly and deeply in the groove, tracking ability is reduced. In order to compensate for this, one must increase the downward pressure ( tracking force ) applied to the cartridge. This can be verified if you have test LP's set up to measure the tracking ability of an arm / cartridge combo. In severe situations, the stylus will literally be thrown out of the groove. Needless to say, this is not good and is not only offers audible proof that this type of mat is not beneficial to performance, it offers visible proof.

6) Besides all of the above, a non-supportive platter mat that does not fully support the record and somewhat "floats it on a cushion of air" or "decouples it from the platter" allows the disc to be influenced by air-born vibratrions to a much greater degree. This can lead to increased amounts of acoustic feedback and lower resolution. This is especially true if you like to listen at higher volumes or have speakers that are capable of room shaking bass. The records can actually "micro-vibrate" to the beat of the music being produced at volume by the loudspeakers as they move great amounts of air. This in turn can modulate the stylus within the groove which results in less accurate transfer of information from disc to stylus. As such, all of the isolation or coupling that one has done to minimize TT chassis induced vibration goes out the window as you've increased the problem of "micro-vibration" directly at the record to stylus interface. This results in a greater amount of "haze" and loss of true detail while adding artificial artifacts to what you are hearing. Granted, the artifacts sound "musical" in many aspects as they are directly derived from the beat of the music that is helping to modulatate the stylus within the groove.

As one can probably gather from all of the above, i'm pretty opinionated about this and most any subject that you throw at me : )

Honestly though, i've taken steps to try and miminize all of the above problems and that is why / how i found out what i now know. This knowledge is based on first hand experience with a lot of testing involved. Being a technician by trade, i want to know and understand why something works / doesn't work, so i've tried to do things in a manner that helps me break things down to the point that i can better understand the situation.

As such, i've ended up using a very heavy chassis on the turntable to minimize the impact that external vibration might have on it. The platter and arm are suspended so as to further isolate any vibration that might make it through the already mass loaded TT chassis. The platter is heavy to increase flywheel effect, i.e. minimize speed variations due to taking advantage of having the momentum of high mass already spinning, the platter mat is fully supporting of the disc, the disc is anchored at the spindle via a clamp to increase coupling to the platter and minimize air-borne vibrations, the outer edge is secured in place via a vacuum platter to minimize the effects of warpage while also increasing coupling to the platter and the arms that i use are linear tracking in design to minimize tracking error and keep the stylus as centered within the groove as is possible. These arms also allow adjustable VTA "on the fly" so as to be able to compensate for the slight differences in vinyl thickness.

While i know that there are many different thoughts on the subject, this is what i've found to work best. Obviously, others might have different points of view. As such, i'd love to hear them and why they have those thoughts. I'm never against trying to learn or comparing notes : ) Sean
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Sean, I would have agreed with you totally -- and did for a long time. Then a friend convinced me to actually try a Ringmat. Back and forth, clamps to Ringmat (adjusting VTA with my JMW arm) and it ultimately became all too obvious. The Ringmat ruled. Like they say, YMMV. Cheers
No problem Dave. I'm glad that you found something that worked for you and gave you the results that you were looking for. I had tried the Ringmat on one of my previous tables with a pivoted arm and did not like the results. As such, i have never given them second thoughts and had moved on.

Is it possible that the added mass of the clamp that you were using or the manner in which the clamp was applied could have contributed a negative aspect to the TT being used ? I have never used a VPI but have seen the internals of one courtesy of United Package Smashers ( UPS ). To me, the table was of lighter construction and lacking mass, therefore making it more susceptible to both air-borne and floor-borne vibration. On top of this, the suspsension did not appear well suited to adding much additional mass to the platter. If the springs were already soft / and or not properly adjusted and you added additional mass to the platter, you might have increased the coupling from the TT chassis to the platter. If that were the case, going to a lower mass platter mat and removing the clamp might make all the difference in the world. Keep in mind that i am not critiquing your choice in gear or how it was set up, only commenting on the possible reasons why we might have observed such different results.

Obviously, others may have different points of view and experiences and i'd be glad to hear from them also. Sean
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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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