Very nice article, Gregadd.
I think I became more aware of this recently with my SME 30 turntable. I have always been in awe of its precision, so I always used the screw down clamp as directed. I have been a bit terrified of it, though, because it requires some force and distorts the record to clamp the record to the machined cork surface. Without the clamp, the shaping of the cork surface does not easily conform to an unclamped record.
I know from experience with implants that any metal over time can fatigue, even with small regular forces, so I have been thinking that someday the turntable spindle would just snap off. Instead, recently the threads on the puck stripped, making it passive but also rendering the clamping system kaput, because the cork surface is carved to accommodate the precision clamping stresses and shape.
I thought about getting a new puck, but instead, tried mat materials of felt and leather.
The standard clamping system always left a bit of rattle in the vinyl, which I think could make it vulnerable to airborne vibrations, as well as acoustic feedback from the needle itself.
The mats have actually improved the performance of the turntable to my ear by better damping of the vinyl surface.
SME's have been accused of having a "digital" sound, because of a bit of upper midrange emphasis. The mats cleared this up, fuller midrange, better defined bass, smoother highs and upper midrange, without detracting at all from the sonic performance otherwise. I surmise that the table is excellent for ground and mechanical vibrations, but that the original clamping system made the vinyl itself more vulnerable to airborne vibrations and some vinyl rattle.
Never thought that a few dollars worth of material could improve an expensive turntable like that, so I am keeping the mat system using the puck as a passive weight. I also don't have to worry about the stressful forces on the spindle/record/puck engendered by the screw clamp system.
