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.
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.