Lewm
I have seen whole threads devoted to how to tie a particular kind of knot that causes fewer problems than some other kind of knot.
There are threads for every audiophile problem.
You run the knot on the outside. The key is the tension and this changes with the material used, and the type of platter/bearing/plinth. .
A) There are tables designed for thread, and people use them with belts.
B) There are tables designed for belt, and people use them with thread.
Its not hard to imagine the results.
But since the OP owns a technics sl1600 I don’t think he really cares.