Chris Harban advised me not to switch to a much heavier platter.
That the 301 motor was not designed to move that much weight.
@mglik
Yes I agree with Chris on this. The 301 motor is not as powerful as the later 401 and in my experience the timing and coherence of the bass deteriorates with heavier platters on the 301.
On my 301 after trying heavier platters & bearings I stuck with the original platter.
The original 301 platter is slightly concave and you cant use metal or rigid mats on a concave surface. So i had the top surface of my original 301 platter very carefully precision machined flat and rebalanced. You have to be very careful and need a precision engineer, else you can lose too much meat off the platter and it becomes more resonant.
In terms of mats I have the following in my collection -
Final Audio 4.8kg copper
Micro Seiki 1.8kg copper
Goldmund methaclyate
Sumiko Compositions barium lead/methacrelate
SAEC SS300
Seisin Engineering ADS3005sp mk2.
I also have a collection of weights & clamps from Final Audio, Goldmund, Audiocraft and others.
With the original 301 platter machined flat, I prefer the SAEC & Seisin mats with no clamp or weight. both mats are not heavy and improve the sound without upsetting the balance.
You might want to talk to Chris about how to get a level surface platter - it might be better to buy an aftermarket platter from CTC to get a platter with a level surface - and then machine it down if necessary to match the original plattters weight.