Swapping Platters on Thorens 124

Anticipating. I haven't wanted to try it because I don't want to risk damaging the Decca. I also use a Herbie's mat with mine and it's super thin. I was able to grab a non magnetic platter for cheap so I thought I'd give it a try before I invested in a new aftermarket one. 

What mat do you recommend that could block the magnetism if I want to keep the aluminum top platter?

Thanks for responding!

I have been told (by Art Dudley) it is the sub-platter on the Mk.1 that is ferrous, not the top platter. True or false?

Yes, that is the case. I have an aluminum top platter which is a great upgrade but still use the iron bottom platter. I've just purchased a Woodsong Audio thingy that replaces the pop up 45 mechanism so any mat will work and I bought an Achromat to hopefully raise everything high enough so the Decca will work. Fingers crossed. 

Thanks @dhcod. I too use London's, and am myself interested in getting TD-124. Keep us appraised, ay?

I have a MKI with the Woodsong hub replacement and a Tenuto mat. I have no problems with my Decca’s or SPU’s. That said I didn’t have a problem before I had the thick Tenuto mat either. I know these issues must be based on some type of genuine historical mismatches, but I’ve never had a problem. Just make sure you measure VTF from on top of the platter. I do notice VTF increases on top of the platter vs outside of it, but this hasn’t been detrimental to my ears.