I don't have a VPI but I do use a washer and threaded clamp - on the SME 30. When the LP is clamped in place it is perfectly flat. The washer is metal.
Incidentally, we are seeing more and more record weights on the market that do not give priority to bonding the record to the platter. Usually these are relatively light (300-400gr - much lighter than the SME clamp) and do not screw down.
Rather than channelling disc resonances away through the spindle and main bearing and/or by optimising contact between the record and the platter surface (in the case of SME, covered with 'Isodamp'), they seek to absorb them directly (i.e. into the clamp itself).
Two outstanding record weights of this type are the Kuzma Ebony Record Weight and the HiFi Tuning VRO ('vinyl resonance optimiser -there is a review for those who read German at: 'http://www.fairaudio.de/test/phono/2010/test-platten-klemme-hifi-tuning-vro-1.html).
The Kuzma Ebony is a particularly interesting case since it has been introduced by a company that supplies screw-down reflex clamps as standard on its high-end turntables.
My question is: has anybody had any experience of these clamps - probably 'vinyl resonance tuners' is a more appropriate term - on their turntables as replacements for screw-down reflex clamps? Clearly as a way of dealing with warped or dished records they will not be of much use, but it may be that they do a better job of damping the disc.
