Mosin -
Absolutely right, I used mass loosely. I read somewhere the EMT idler has a platter of 5.5kg ( same weight as the copper mat on my deck ) but due to its weight distribution ( 16 & 1/2" platter ) is the equivalent of a 50kg solid platter. Although not as radical my TT has an inverted bearing with a substantial subplatter which is an inverted truncated cone (frustum), so most of the mass of the 20kg platter is between the inner and outer grooves & the thickness increases inside out ( and below the bearing point ). So yeah the effective mass of my TT platter is well in excess of 20kg.
Absolutely right, I used mass loosely. I read somewhere the EMT idler has a platter of 5.5kg ( same weight as the copper mat on my deck ) but due to its weight distribution ( 16 & 1/2" platter ) is the equivalent of a 50kg solid platter. Although not as radical my TT has an inverted bearing with a substantial subplatter which is an inverted truncated cone (frustum), so most of the mass of the 20kg platter is between the inner and outer grooves & the thickness increases inside out ( and below the bearing point ). So yeah the effective mass of my TT platter is well in excess of 20kg.