platter mats for dd turntable?

It's worth bearing in mind that the Technics 1200's platter has a slightly raised lip all the way around the edge. Some companies are starting to notice and provide slightly smaller mats that fit inside this lip. I've had best results with a SoundDeadSteel Isoplatmat (285mm to fit the 1200) directly on the platter to damp any ringing and a Funk Acromat on top to interface with the record. This combination only lowered the noise floor a touch, but it did things with air and space that I hadn't heard from a Technics before.

I wouldn't worry too much about matching the original mat's thickness - the Technics' VTA adjuster is very flexible and has quite a wide range.

Sorry, but I'm afraid I don't buy that.

Firstly, the outer edge may only be raised 0.008 inch, but vinyl reproduction is all about precision. Compare that to the width of the groove that the needle is trying to trace and it suddenly doesn't seem so negligible.

Secondly, with my 285mm Isoplatmat (NOT touching the raised edge, remember) and Acromat on, I get a satisfyingly dull 'thunk' when I flick the edge of the platter. The ringing is completely damped without anything touching that rim at all. As an added bonus, I know my records are sitting on a perfectly flat surface with no possibility of dishing in the middle.