coupling or decoupling of vinyl to/ from platter


Dear all,

I'm puzzled by a number of claims about record clamps and mats. 

I own an old Rega Planar 3, and I was reading about the importance of coupling the record to the platter, to add effective mass to the record to reduce vibrations, slippage etc, and improve the solidity that the groove "image" presents to the stylus. 

I also read about the importance of de-coupling the vinyl from the platter to prevent the transmission of unwanted vibrations from the motor. Rega has a very dense platter made of glass with a fluffy felt mat on top. So, felt to decouple lp from platter, is that right? 

Then, I purchased a cork Music Hall mat, which has a dozen raised cork discs on the mat to BOTH "decouple" the lp from the platter and "grip" the lp.  Music Hall claims that clamps are unnecessary with this mat because coupling discs, etc. I also, without knowing this, purchased a Rega Michell record clamp. The clamp seems to do good things regardless of the mat, and of course evens out warped records a little bit. 

There needs to be, it would seem, a clear objective answer to all of  this from an engineering perspective. Coupling does x, and decoupling does y.  If you look at all the high-end turntables, they have massive platters and clamps. So coupled mass is good for flywheel effect and also  for presenting a solid "image" to the stylus? 

Either Rega and Pro-Ject are dead wrong with felt mats, and have been runaway successes in spite of this, or the felt is adapted to their setup: weak motor, relatively light but super-dense platter, and decoupling felt to manage the motor and rotational noise transmitted up the spindle, and to hell with coupling?  

I did some quick and tentative experiments with the Music Hall mat and clamp vs. Rega felt mat with clamp. I need to do more comparison. The results are different but hard to characterize. I'll post again with more comprehensive subjective tests. 

From an engineering perspective, which should be best, Rega clamp w felt, Music Hall mat by itself, or "screw the mods, Rega it great just the way it is, heretic!!!" ?

Let the games begin!

Paul

paulburnett
If the LP has to be decoupled from the platter to get rid of motor noise, the turntable has a really serious problem and should be repaired.

I think we can discount that explanation.

A proper platter pad does several things at once, that is if its intended for best reproduction as opposed to DJ service:

damp the vinyl
damp the platter

To do this properly the pad has to be very nearly the same hardness as the vinyl, to avoid reflected energy. Yet it has to have damping properties.

You can see right away that bare glass or metal is too hard and won’t damp the LP properly. If the mat is really doing its job, the stylus tracking the groove will be relatively mechanically silent. The purpose of felt platter pads is to act like a clutch so the platter can rotate while the LP is held still. This is for DJ work; such pads can improve the sound if they are interfacing between the vinyl and the bare platter but other materials can work much better.
As always, atmasphere has the straight story.  I bought a Planar 2 new in 1981, and its glass platter was thinner than the 3.  Accordingly, the standard issue felt mat wasn't quite thick enough to get the VTA into a decent sounding range.  I went with an Audioquest Sorbothane mat and clamped my vinyl with an AQ clamping weight.  Took out some warpage, dishing and pretty much killed all resonance.  Used the rig with a Dynavector MR23 Karat LOMC to very good effect.  Others here have had very positive things to say about cork with Rega and others, so you might want to research the archives for more info.

I never got an opportunity to try a cork mat; didn't have any dealers vending them at the time and I wound up upgrading to a Sota Sapphire in early 1984.  Its mat was both resilient and non-resonant out of the box.  I fitted a Magnepan Unitrac I to it, so never had to worry about VTA again.  I did find that the AQ clamping weight wasn't quite right, so I went to the Sota I-Clamp (low mass screw type compression) and was happy for a number of years.  Even so, the I-Clamp was awkward to use.  Found the Sota Reflex clamp second hand at a very good price and love it.  I highly recommend it for use on any table.

Either way, have fun and enjoy your Planar 3 - it's a very nice unit!
I had the Planar II with the 10mm glass platter - it rung like a bell - sounded awful.

I also tried the sorbothane mat  and it quelled the ringing and I was happy :-)

Or so I thought, but when compared to other TT's it sounded lifeless

I've since ...
- ditched the glass platter for an acrylic platter - no mat and no more ringing
- added a Thorens Stabilizer weight - to keep the album spinning with the platter (not slipping) - improved dynamics
- replaced the plastic sub-platter with a metal one- improved clarity
- replaced the plinth for something that actually works - it stops ALL vibrations
- replaced the arm with one that actually works well - it got VTA :-)
- OK - the lid works well - so I kept that - and the on/off switch

The result: - clear, detailed, dynamic and precise reproduction.

It's no longer "a Rega"

 BUT, I'm really happy :-)

Regards - Steve



I've also been curious about this. I have a Pro-Ject Debut Carbon DC Esprit SB with an acrylic platter. It shipped with a felt pad and I've used it with, and without, the pad, but never really paid attention to any sound quality or noise differences. However, I've seen a few very nice leather pads that look awesome, are thinner and should provide a bit better traction for the LP on the platter.

Anyone have any comments on using a leather pad? Also, I'm not currently using a clamp/weight. Is this something I should try? Is a simple weight OK? I don't want to put too much pressure on the spindle every time I install the device.
Rueben - I don't have any experience with leather pads, but given that your turntable has isolation feet, and MDF plinth and acrylic platter, you're already pretty much where you want to be and I would avoid using the felt mat altogether.  Just make sure that your vertical tracking angle is appropriate.

If your pro-ject has the threaded spindle, the threaded clamp that pro-ject ships with some of their higher-end tables would be a nice addition as it allows you to set the pressure precisely.

One other thought for this thread (that was alluded to earlier) is that vinyl is usually the best coupling surface.  I'm surprised that people with glass/ MDF, metal platters don't simply use an unwanted LP as a platter mat.

Greg
@gregkohanmim - Thanks. I do not have a threaded spindle, hence my curiosity about using a weight. I’ll take the felt back off and take a listen without it. Not sure the Pro-Ject carbon tonearm that comes on the Debut Carbon has a VTA adjustment. I’ll check again to see if I can find any information about VTA adjustment for this arm.
reubent
... I do not have a threaded spindle, hence my curiosity about using a weight ...
FYI, there are clamps that work without a threaded spindle. KAB makes one, the Record Pig is another.
Ruebent- You're right - Looks like your arm allows tracking force, anti skate and azimuth adjustments only.

Greg
While on the one hand,  I do not disagree with anything Ralph (Atma-sphere) wrote on this subject, I wonder why there are so many vinylphiles who swear by one or another metal mat, most typically copper ones.  I own an SAEC SS300 metal mat, which I think is made of aluminum, and it too sounds great to my ears on any of 3 turntables where I have used it.  But other than the SAEC, my own favorite mats are the Boston Audio Mat1 and Mat2, which do conform to the concept of maximizing energy transfer between the LP and the mat/platter.  Just lately I have been messing with a comparison of the SAEC vs BA Mat2 on my Victor TT101 turntable, and I am surprised to discover that the SAEC may be my preference.  Whereas, on my Technics SP10 Mk3, I prefer the Mat2.  These are both high end vintage DD turntables, but one (the TT101) uses a coreless motor and a rather light platter, while the other (the Mk3) uses an iron core motor and a very heavy platter.  It could be that the SAEC mat is acting as a shield against EMI from the TT101 motor, and that's the main reason why it may sound best.  (The orientation of the magnet structure in the typical coreless turntable motor is such that EMI fields will radiate in the vertical direction; whereas in iron core tt motors, the radiation is more in the horizontal.) Perhaps that is also why so many other DD lovers prefer copper mats. So, mats are a complex issue. It may not be all about mechanical energy dissipation.

Isolate the whole gol dern thing. Then nothing will ring. Not the platter, not the tonearm, not the cartridge. All of which resonate at frequencies that are primarily seismic in nature. And if they're not ringing there's no need to damp them. Hel-loo!

I don't understand the answer to the op's question.  Are we decoupling the record from the platter by using a mat, and then coupling the record to the mat via the clamp and sometimes a peripheral ring?

In my case, with a Classic 1, VPI recommends against a mat.  To reiterate the original question, what's the theory?  As Denzel Washington's character said in the Philadelphia movie,"explain it to me like I am a four year old".
^^ Geoff is right. Isolating your deck is the starting point. I use maglev feet.

I´m not excited in damping the vinyl, damping the platter (from motor noise) is completely another thing. Coupling/decoupling is complicated in any case.
Sorbothane mats and Groove Isolator by ORACLE do a good job but hard (acrylic) mats spoil the good sound IME with different Delphis (BD) and one Goldmund Studio (DD).


In my case, with a Classic 1, VPI recommends against a mat. To reiterate the original question, what's the theory?
I explained the job of the mat- it is ideally a damping device.

The problem is that when the stylus tracks a groove, the vinyl resonates a bit and so can talk back to the stylus. By damping the vinyl, the talk back is reduced and so the resulting signal has less distortion. You can tell this is happening; if the LP is being damped the stylus will be inaudible with the volume all the way down. If the LP is not damped, you will be able to hear the stylus tracing the groove from across the room.

I´m not excited in damping the vinyl, damping the platter (from motor noise) is completely another thing.
You can't damp motor noise with the platter pad. If the motor is not sufficiently decoupled (IOW its noise is apparent when the stylus is in the groove) then the turntable needs repair or replacement. It really is that simple. I agree that acrylic mats don't sound right- they are too hard and don't match the durometer of the vinyl so energy is reflected back into the LP and picked up by the stylus.
atmasphere,

Thanks for the explanation a four year old can understand.  I did the experiment you suggested, turned the volume down all the way and could hear no groove noise at all with my ear within inches of the cart/stylus.  I am running a MM cart with it's relatively high output and could hear the internal signal of the cartridge.  This is with the VPI Classic 1 with the heavy aluminum platter, center clamp, and periphery clamp.  It seems to work without a mat.  If I had a mat I would try it, but from what I have read from other owners it offers no improvement.

Here are some further words of enlightenment from George Merrill:

  Debunking LP Record Weights and Clamps
by George Merrill

The LP record ranges in weight from approximately 80 grams (Dynaflex 1969) to 200 grams. Most pressings weigh from 100 to 130 grams. One reason the heavier and thicker records sound better is the vinyl will not vibrate to the degree as the light weight records. The 180 and 200 gram records are the choice for less vibration, and can render better sound. The rule is simple, the more damping applied to the LP the better it sounds. This result can be obtained from its own vinyl mass or external. To achieve the best external damping, the record vinyl needs to come in total contact with a vibration damping material (mat). In the past a few record mats have used small rings or points to support the record in a few places. This flies in the face of common logic.

Holding the record to a damping material is the job of weights and clamps. An LP record’s label is thicker than the vinyl playing surface. The label varies from approximately 20 to 60 thousands of an inch thicker than the vinyl. A record mat will have a depression in the center to allow the record vinyl to lay flat, otherwise the label would be the only contact point. If a center weight is used that is very heavy, let’s say 2 lb. the lighter records will lift from the mat. This happens because the mat depression edge will act as fulcrum. This information tells us we should use a center weight tuned for the record thickness and weight. However this is impractical. Here is the solution: Use a center weight that weighs 8-12 oz . This weight will work with all but the lighter records. The alternative to a weight is the screw down clamp. These clamps have pluses and minuses. The plus is down force on the record can be controlled. The minus is if not designed properly (unfortunately most are not) spindle energy is coupled into the record. It takes very little intrusion of external energy to cloud the mechanical output of the stylus. (I wrote a paper on proper screw down clamp design about 25 years ago.)

The best answer is the periphery clamping weight along with a center weight. The weight balance between these two should be calculated for even and optimal down force on the entire vinyl area.

As the stylus traces the groove, energy is radiated in all directions, as it reaches the periphery of the record it then reflected back into the groove area. The periphery clamp will help damp this edge energy before it is reflected into the groove area. The center weight also acts as a damper. The first production periphery clamp was used on the Merrill Heirloom Turntable 1980. Kenwood also introduce theirs about the same time. Other manufacturers are now discovering the benefits of this type of clamp system.

If a center weight is used that is very heavy, let’s say 2 lb. the lighter records will lift from the mat. This happens because the mat depression edge will act as fulcrum. This information tells us we should use a center weight tuned for the record thickness and weight. However this is impractical. Here is the solution: Use a center weight that weighs 8-12 oz . This weight will work with all but the lighter records. The alternative to a weight is the screw down clamp. These clamps have pluses and minuses. The plus is down force on the record can be controlled. The minus is if not designed properly (unfortunately most are not) spindle energy is coupled into the record. It takes very little intrusion of external energy to cloud the mechanical output of the stylus. (I wrote a paper on proper screw down clamp design about 25 years ago.)

George misses an important element of clamps, which is that to gain the most out of them quite often a spindle washer of some sort is used beneath the LP so that the clamp can dish the LP against the pad surface. This can also be used to reduce warp.

I generally don't use the clamping aspect of the clamp I use (Basis; one of the better clamps made), I just use it as a weight. Its easier.

Many years ago I saw a demonstration of how profoundly a mat can affect a turntable. A friend of mine who has been involved in several damping products over the years (Analog Survival Kit, the damping rings used by ARC, the Ultraresolution Technologies damping platform) spent some years developing a platter pad. He arrived at a fairly high degree of refinement with the mat. What local audiophiles found was that any turntable that could accept the mat (due to height and weight; it weighed about 3 pounds) sounded better and also sounded better than nearly any turntable that lacked the mat.

This seems to hold true to this day. IMO/IME most mats out there don't seem to do the job as ideally as I laid out in my opening post (IOW it was a statement of the engineering principle behind the mat, not actual execution). This is why you see so much variance in opinion about the topic.
For several years I owned a Kuzma Stabi table, the model with the heavy wood plinth.  The platter was thick aluminum with a lead insert on the underside to add mass and the mat seemed to be a treated (?) cloth glued to the platter.  It included a tapered spindle washer and threaded clamp as Ralph describes.

I found that to be very effective for both damping and flattening records. Because the spindle clamp was threaded you could adjust the downward pressure.  With some records excessive pressure could slightly lift the outer edge of the LP.  My table was mounted high enough so I could see if the record lost contact with the outer edge of the platter, I would then unscrew the clamp slightly to regain contact.

This system worked well with dished records, but only for one side.  Moderate warps (wavy) were also reduced.

The Kuzma was silent so I judged that design to be effective for both damping and flattening purposes, though I never tried an outer ring.
atmasphere, I wanted to say reduce/lessen (motor) noise (excuse my clumsy English). Of course, this alone can´t  fix defective motor or wrong placement of motor. Rubber mat on metal platter lessens noise from outside and lessens metal´s ringing. This is basic physics ? Thick and heavy Groove Isolator on aluminium/magnesium platter reduce noise (ringing). ORACLE´s clamping system is exactly "dishing" record tightly against Groove Isolator and thus platter, and reducing warps. Actually all three become an unity. A very effective damping method, one of the reasons why ORACLE sounds so good, IME at least. This damping method simply works surprisingly well (can´t explain it really). Unfortunately ORACLE took a few steps back replacing Groove Isolator with hard acrylic.

On the other hand, damping the record too much may have serious side effects like compressing the sound, in various extents depending on platter /mat in question. Very complicated anyway.

As I said I´m not excited in damping the vinyl TOO much, I meant to say.
The other option is let the vinyl breathe, but that, of course, is another story.
This is so interesting that you say this about breathing Harold. Tell us more about this other story! 

Using the clamp and Music Hall cork mat, the signal seems more locked, with the proverbial blacker background. But I get a more left-to-right, 2D soundstage. On the other hand, unclamped with the felt mat, the Rega seem to present a more three-dimensional, front to back soundstage. Am I just interpreting smearing as depth? One possibility is that the two mats alter the VTA, which looks like it might be the case. And since I can't adjust the VTA on my current setup, the Music Hall will likely have to go back.

Can I get the 3D image with the black background and locked image please? ha ha.  The other issue might be that the Music Hall raises the record off the platter with a dozen cork discs, so it's not truly coupled to the platter.  I'm ordering a Herbie mat for comparison. 
IME, the difference in image you are hearing between the 2 mats is almost entirely VTA.  Even a very minor adjustment makes an enormous, immediately audible difference regardless of cartridge.  It's the reason why VTA adjustment on-the-fly can be such a desirable feature in a tonearm.  

An easy way to confirm if that's what you're hearing is to play a well-recorded thinner record and then play a well-recorded thicker one next using the same mat without a clamp.  Then repeat the process with the same two records with a clamp.  Repeat that combination again with the other mat.  You will learn much.

Happy listening!
effischer, you are absolutely right. Thanks for reminding VTA´s importance.

Paul, thanks but I´m just a retired gardener not an audio expert really.
One answer for the dilemma is the Reso-Mat. Ask the designer himself, Vic at Trans-Fi Audio, UK.

@paulburnett 

You say "There needs to be, it would seem, a clear objective answer to all of  this........ "

Sorry Paul, wrong hobby for that !!!

I have used an audioquest silicone mat for years and a clamp. I think the combination works great
I use the  FUNK FIRM Achromat on my souped-up Techincs DD table and it seems ideal for absorbing energy from the LP.  It also has a small depression for the label.  I sometime use it with a 1050g brass weight, but that doesn't seem to make much of a difference.   No others have tried the Achromat?
Yes , Funk is best, screw the rest .
Well in some 45 years plus experimenting with turntables, tonearms, mats, drives, isolation racks, cartridges, phono cables, power cords, clamps, etc., I have had the many experiences above. At one extreme, I had a Final Audio turntable. It was all pure copper and the platter weighed 150 pounds, had no mat that was about six inches thick, There was a column of bronze with a cap that you could have drilled for your tone arm, and a bearing that weighed about 70 pounds of solid copper also. I don't remember was the bearing surface was. None of this was bolted to a base, you just plunked it down and got your adjustments by gently moving the tonearm column and the motor to get enough tension. You had to start it by using you finger to spin it. It was a string drive. 

In short it was extreme, but it only sounded great sitting on our foundation floor  and we had a three year old son!

Today, I have a Jean Nantais/Lenco idler wheel drive with an Ikeda 407 Long tonearm and their 9TT cartridge. This all weighs over 100 pounds and sits on a Stillpoint ESS rack with Grids and Ultra Five isolators. I have two record clamps-one the Star Sound Tech Platter Ground and the other the Dalby Record Stabilizer. Finally I use the High Fidelity Din to RCA tone arm cables into the BMC MCCI phono stage with special RCA to XLR adapters into the MCCI.

Frankly, I have never had anything close to this vinyl reproduction. I think it is largely immune to stylus vibration, music vibration, etc. and provides a very rich sound stage and real instrument fidelity and location. I am happy!
Post removed 
tbg,

Can you tell what Final Audio model exactly and why on Earth did you abandon it ? It´s regarded very high among many high-end audiophiles.
Because of your little son ? C´mon.
Perhaps the same reason he abandoned fifty other systems. 😬
@tbg
Would you mind elaborating on the differences you hear between the Final Audio and the Jean Nantais turntables? 
Cheers.
Dear tbg, we are all open ears... 
Guys, I sometimes ask myself the same thing. All that I can additionally say is that this was in the early 1980s and my funds were more limited. I would dearly love to still have it and to compare it with the Nantais.

The Final would be more of a pain, but 185 additional pounds would likely contribute much. Also 285 pounds is right at the limits of the Stillpoint ESS rack. I also imagine that the Final would be more variable as the copper expanse and contracts.

Finally, my listening room was still the great room of the house and my wife was enjoying the music as her loom was also there, but also alway complaining about the 'laboratory' look of the room. 

When our kids had gone away to college, we sold this house and I got my 18 x 28 x 11' room just for me.

I have never seen another Final Audio.
Just got up from Asylum (where my gear is).
What a great story, like a fairy tale, quite a touching one. I almost cried. 
But the laboratory view made me laugh out loud :)
I´m also living in a cave, most of the time ;_).

@tbg I'll bet "the laboratory" was dusty with your wife weaving in it. My wife is into textile crafts too and the dust created is phenomenal and not a great mix with vinyl records.
@Paulburnett   You will love the Herbie's mat, I just got one on my VPI SSM and the difference is nothing short of amazing
George Merrill at one time made a platter with a sealed layer of lead on top. Then there are the graphite mats, which some love.
Interesting. If you look at forum topics regarding the use of 180g for new audiophile releases the general view seems to be exactly the opposite of what Merrill proposes?
Folk seem to prefer 120g to heavier vinyl.
They also seem to think it is little more than a marketing ploy.

Personally I hear little difference but I'm not a damping-is-king kind of guy. It may be attributable to the scheme that I use.
I use a Mitchell record clamp as it makes me feel better about myself, and my trusty old Linn Basik/Akito rig sounds clean as a whistle (a better DIN cable helped), and a dude at Goodwin's insisted I buy an Achromat…I ignored him. I like a lot of new 180 gram vinyl I've bought over the years, as well as other thicknesses, and don't feel it matters much. I added a new and better designed Audioquest brush recently and it gets static electricity from the vinyl to run through YOU (or me in this case)…causing instant memory loss (heh heh).
Reubent
In regard to leather mats, I've been using the moo mat for a couple years & prefer it over the music hall cork mat mentioned above. My table is custom built with a 4" solid aluminum platter. I use a heavy 2 piece weight which was also custom built. There certainly is a difference so I can see why it would be a fine mat on another table, but the moo mat sounds better to my ears on mine. The music hall mat sounds delicate in comparison. With the moo mat there is more of a "being there" there.