When I was at the last BAAS even on Dec 6, I believe it was there I heard the best explanation of 'to clamp, or not to clamp'.

Basically, some clamps can reduce the noise of a turntable and help flatten the record. Other turntables that send a lot of vibration up through the spindle and can make a record sound worse when clamped.

I guess it is all just trail and error. but my concern would be increasing resistance on the bearings and the belt which could slow revolutions per minute down.

which on my rega maybe wouldn't be a bad thing, if it just slowed it down. i've had the feeling, especially on the tracks close to the label, that sometimes it speeds up.

there is probably a way to test the speed isn't there??? isn't there???