Felt Mats or ???

Dave,

That makes sense. Zinc probably wouldn't be so good for resonance control either. I doubt anyone clamps directly to that platter, especially not "bareback".

Good warning re: not clamping a Boston Audio Mat. If Nrenter decides to try he should MAKE SURE TO REMOVE THE REFLEX WASHER (or drill out a bigger hole in the mat, heh!). I actually cracked an LP in half once with my Teres clamp. I'd put two reflex washers on the spindle by mistake and couldn't figure out why the *&^% record wouldn't flatten out. I tried one more turn and SNAP! - it went from un-flat to really, really un-flat. Idiot...

Of course the biggest danger is swinging clamps around near mega-dollar cartridges. I consciously developed a movement drill so the clamp never passes over, under or near the tonearm. Taking out a $5K arm plus an $8K cartridge in a single dumb move is too scary to contemplate.

Doug

Like Ddarch44's modded Merrill's, the best sounding mat for tables like my Teres is no mat.

Some tables are designed for close coupling of LP to platter. Teres uses a threaded spindle and clamp, which ennables very tight (and adjustable) coupling. If a periphery ring is also used it's sometimes possible to approach the coupling achieved by tables with vacuum hold down. If an LP is flat to begin with I often have to peel it off my platter after clamping, since the right amount of clamping can actually create a vacuum-like seal. The reduction in background noise and improvement in low level detail retrieval is noticeable.

When clamping I use the ever popular "rap-the-deadwax-with-a-knuckle" test to determine optimal clamping pressure. When pressure's just right (usually very tight, on my table), resonances from a rap dissipate rapidly with minimal echo or harmonics. IOW, the thump sounds "dead", not "ringy". This indicates good vinyl/platter coupling that will dissipate stylus/vinyl resonances effectively.

Other tables produce other sonic results of course. Some clearly benefit from a mat. On others there could be tradeoffs that would make a winning strategy unclear.

Mats are largely intended to isolate the LP (and thus the pickup) from various noise sources. They're a relatively inexpensive approach to engineering challenges that can, for a cost, be more effectively addressed by eliminating the noises at their sources.

To benefit from no mat and tight coupling without sonic detriments, a table must have:
1. low or no noise from the bearing
2. low or no noise from the motor
3. low or no noise from whatever system couples motor to platter
4. a platter which effectively dampens or dissipates vibrations emanating from the stylus/vinyl interface

Assuming a table has achieved 1, 2 and 3, achieving #4 becomes an interesting challenge in platter and bearing design. Different tables use different materials and designs, lead is often involved for example, with varying results of course.

Tables which have effectively addressed the above (very challenging) issues rarely achieve additional playback accuracy from a mat. This comes as a great relief to those who've already spent crazy amounts of money on their TT - at least there's no need to spend more on a yet another tweak! ;-)

Nrenter,

Great insight and an interesting spin. Clearly a mat could be combined with a clamp to provide a coupling system. That isn’t the way mats normally get used but on the right table that’s no reason not to try – and you may have exactly the right table.

As an example of the wrong table, consider my old H-K/Rabco ST-8. Its noisy bearings (#1), motor (#2) and multiple belts (#3) all precluded clamping. I tried it and it seriously raised the noise level. Letting the LP float in isolation on the mat sounded best.

Your much better rig addresses issues 1-3 well, so the biggest remaining challenge from my list is indeed #4. We’re agreed that acrylic alone does not effectively control intra-vinyl resonances and those are very destructive of good playback, as George Merrill’s, Ddarch44’s and now Dopogue’s results all attest. (Dopogue’s platter is also solid acrylic, so his preference for a mat is consistent with all this. Apparently VPI should be selling Ringmats, not clamps!)

So, using your clamp to couple to a mat could provide valuable resonance dissipation, while your table’s good behavior on #s 1-3 prevent any of the potential downsides that lesser tables might suffer.

Put a mat on your holiday list!