2. analog
  3. 129186-1601

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

Showing 2 responses by tbg

tbg
5,263 posts
 
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!
tbg
5,263 posts
 
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.
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