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Effect of Mat vs. Changing VTA?

naimnut

Deep in the Mines of Soul
After reading recently on another thread some posts written by folks who have tried and been impressed by the Plattamat, I recently did an experiment of my own.

I have two turntables side by side. I have an LP 12 with Linn felt mat and a Numark dj table with slip mat for djing, scratching, etc. The slip mat is about one-third the thickness of the Linn felt mat. That's a rough guesstimate.

I swapped the Linn felt mat for the thinner and somewhat firmer mat from the Numark and was surprised at the change in the tonal spectrum. My assessment must be considered preliminary but I think the upper midrange and treble were clearer and louder, very similar (i think) to what others are describing here with the plattamat. I think it is a positive change.

I'm wondering if this might be attributable to the slightly different angle at which the stylus aligns with the groove. I expect the back of the cartridge must be raised very slightly, due to the record itself being a few mm lower. Perhaps it is closer to the angle originally traced by the mastering lathe? This makes more sense to me than attributing the difference to the material of the mat.

What do you all think?
__________________
 
Both VTA an platter material will affect the physics of the deck, and for 2 different reasons. Which is more important is anyone's guess. You can play about with platter mat materials for loose change and get good results. Dealers don't want to get into this though, why would they if they can persuade you taht a £150 interconnect or a directional mains cable is a better "upgrade"?
 
I have a Ringmat on my LP12, which I thought was an "improvement" on the Linn felt mat. I have since added a "base platter mat", which seemed to bring sonic benefits also. Of course each of these will have changed VTA, which I don't think I can do anything about with my Akito arm.

Apparently Ringmat do a full "Support System" comprising spacers to set the VTA depending on the thickness of the LP being played! Not tried it myself but I understand that the designer John Rogers is an officianado on such things and sells a guide on "how to set up and fine tune a turntable", again not tried it myself.

When I bought the "base platter mat" John suggested I might need to reduce tracking force to compensate for the slight change in VTA.

I have been quite happy with what these Ringmat products have brought to the sound of my system but the further fiddling and tweaking of VTA etc etc is perhaps a little more than I can be bothered with.

Cheers
 
I know that some arms provide for adjusting the VTA. I'm not talking about that.

What I'm talking about here is the underlying cause of the change in sound attributed to changing a mat. Of particular interest are changes on an LP12 away from the standard felt mat. My hypothesis is that, since the felt mat is rather thick, any thinner mat, whether a ringmat, plattamat or other mat will change affect the VTA and, hence, the angle at which the stylus enters the groove. If this causes the stylus angle to more closely approximate the angle of the cutting head then it should have the effect of creating a more accurate representation of what is on the record.

Do y'all agree?

Has anyone compared mats that were made of different materials but were of identical thicknesses?

Seems to me that an unreasonably thick mat could have the effect of throwing off the VTA to the extent that lower level detail is obscured, rendering the presentation to be tilted towards the lower end of the spectrum because the higher frequencies on the groove wall are not "visible" to the stylus, at the defacto incorrect VTA caused by the thick mat.

whatcha think?
 
What makes the difference is the effect it has on SRA and the position of the coils relative to the magnets.

Moving your arm up or down 2mm makes next to bugger all difference to what contacts where in the groove.
 
What makes the difference is the effect it has on SRA and the position of the coils relative to the magnets.

Moving your arm up or down 2mm makes next to bugger all difference to what contacts where in the groove.

Dead right.

Neurotic concern over VTA won't pay dividends and the VTA will actually change as records differ in thickness. Temperature and VTF will also change it in many cases.

In virtually all cases, get the arm parallel to the record and leave it there.
 
It is just that the differences in sound attributed to various mat materials only makes sense to me if they are somehow contributing in some different way to the signature of the acoustic feedback that is getting through to the carpet. I'm not saying its impossible, but it doesn't make a lot of sense to me.

To be as clear as possible, I can imagine that a Plattamat cork mat is much denser and, hence, would provide a different level of isolation to the stylus/vinyl interface than the standard Linn felt mat would. But which one provide greater vibrational isolation? Here I feel like I'm out of my depth, technically. Same challenge exists for my mind when thinking about the ringmat. Different isolation, different spectral signature. But why?

But minute changes to the alignment of the stylus tip in the groove seems more plausible.
 
Mats change a couple of things, but leaving differences of thickness aside for a minute the thing they all change is the level of damping applied to the record itself, the differences in how the record couples to the mat and therefore to the platter and the rest of the deck is what counts.

A record on a felt mat is virtually decoupled from the platter, apart from the spindle. There's minimal friction between the mat and record and the mat does very little to damp the record itself, the exact opposite of a grippy silicon rubber mat which damps and couples the record directly to the platter.

Each of these two extremes sounds noticeably different, felt/silicon rubber, even if exactly matched for height.
 
Of course each of these will have changed VTA, which I don't think I can do anything about with my Akito arm.

You can adjust VTA on an Akito.

I have compared lots of different mats, all the same thickness. In my experience, the material the mat is made from makes more difference than the VTA/SRA; the reason has nothing to do with acoustic feedback(as such) though.
 
If it doesn't affect VTA/SRA surely it can only be acoustic feedback? (or by acoustic feedback do you take that only to mean airborne soundwaves as opposed to feedback entering the stylus from the record)
 
Yes, I took it to mean airborne sound waves - I would agree that the issue actually relates to the stylus/record interface.
 
I also noticed this years ago when I had my technics which was way before I knew anything about audiophoolery. There is something to it, at least on the technics heavy metal platter.

I think at the time I put it down to the thin mat offering almost no cushioning and the thick mat being quite soft. If you touch your records when they are on the deck(!!!) you can probably hear or feel the difference.
 
Hi,

This is in the section at the end of my LP12 Set up manual.

3. The use of record weights, or clamps. This will not improve the performance of the turntable. The weight or clamp stresses the record. This stress causes the record to transmit energy in an unpredictable manner. Any time we can’t control the energy in the system we can expect performance to suffer. The sound will change (usually getting "brighter", but it will not be an improvement if you really listen to it.) On top of that, weights can destroy the main bearing, which is already working at a pressure
of two and a half tons per square inch. Adding a two pound weight to the platter increases that pressure by twenty percent. Whatever improvement you may believe you hear will be immaterial as soon as the spindle drills through the thrust plate of the bearing.

4. The use of platter mats other than the felt mat supplied by Linn. Generally these mats decouple the record from the platter. Whether they will, in fact, correct for problems in other tables, is debatable. In the case of the Linn, the decoupling only makes it more difficult for us to retrieve information from the record. Some heavy metal mats cause the same wear problem noted in item number 3.

5. The use of no mat. Resting the record on the bare metal platter sometimes causes a subjective improvement. The record resonates against the platter. The record sounds more "alive"; but a great deal of detail is masked. Please just use the felt mat.

Just for information.

Cheers

John
 
All very good - except that a felt mat is hardly rigid at all audio frequencies, so some decoupling must be taking place. Thick felt mats sound obviously different to thinner felt mats (even when VTA is accounted for).
 
Since many TT have no dial speed change except 33/45 rpm. there is the slight factor of extra or less weight applied with a non standard TT mat. Back at the start of the 80's there was a bit of 'a craze' by some for whopping great heavy mats. One only had to replace the standard mat on a TT (having a speed check light strobe) to see the dramatic speed difference taking place unless readjusted. That is leaving aside the extra weight the bearings had to carry.
Then do we make adjustments and change the thickness of the TT mat according to the thickness gauge of the vinyl record each time, we play particular records? We are looking at Hi Fi hypochondria madness.

What nobody has touched on was the phenomenon, found in the mid 60's with cutting vinyl masters. The heated cutter was causing the material to 'recoil away from it' during the process -causing what was called 'the spring-back angle '. In turn it was found that then pressed recordings mirrored the angle. An angle point checked and measured from tone arm pivot point to stylus point. Cartridge manufacturers then compensated for it., once a cartridge was set up in a tone arm. Reviewers in those days also used test records containing test passages of differing groove angles to check with instrumentation, the compensatory angle the manufacture of a cartridge had set their cartridge.
So saying that, just as experts then warned.....NOW PLEASE DO NOT ATTEMPT to bend the shape of a cartridge cantilever,arm or head shell to 'try out some experiment' after hearing this point, that experts found out decades ago. You will have a bent, badly damaged 'dead' cartridge for sure.

I fear at times of some of the knowledge or thoughts given, can be dangerous...it may cause some to go off and experiment...leading to Hi Fi grief.
It is better to stay with what manufacturers advise...just sit down and just enjoy the music. Nothing is perfect. Let's accept that.
 
Markus......One simple way of quantifying the effects of VTA is, without changing your original mat, to set up your T/T to suit 120g records then compare the sound of 120g with 180 or 200g discs. Assuming you've set the arm up as accurately as possible in terms of downforce for level VTA at 120g thickness there will be a clear difference the critical among us would want to compensate for if they could i.e. by setting up 180g equally accurately?
On the subject of mats, I think your conclusion is still correct. The material and thickness does make a difference (even assuming that the mat has been VTA compensated for).
A thought provoking article :

http://www.soundfountain.com/amb/ttmat.html
 
I think, on reading that linked article, I disagree with more that is stated within it than I agree with.
 


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