Aluminum in cld plinth

I would not think that the aluminum sandwich would be of any benefit. It don't think that it would hurt. It might add a little weight so that could be the only benefit I think. Try it!!! That's part of the game....

I am planning 6 layers of alternate ply and mdf. i was also going to make a 2 or 3 layer platform and use 3 spikes on the bottom of the tt, and platform.

"I would only recommend that you use top & bottom layers out of Ply. or MDF + separate arm board(s)."
Mariusz, can you elaborate here,i am a little slow to get the picture.

thanks

I don't know the details of your design or what TT it is based on. But I would used Ply. or MDF for top & bottom from practical point of view, could be easier to work with on finale details and mounting hardware and such. It may also be a little safer approach ( using aluminium/MDF/Ply. together for the first time ). MDF is a good material for the arm board so is Ply or solid wood. I simply don't have enough knowledge or experience to predict the effect of the 1/8inch aluminium sheet on the arm/cart. I would just play safe for now and if it worked in this project you can always try it next time (top, bottom - Alum.).

Ok now I understand. I was not even thinking in terms of the al as the top or bottom layer, only as a sandwiched layer, or layers.
As for the top layer or armboard is one better than the other ie.. ply, mdf,or hardwood?

I guess I should say the project is a Rek-O-kut b12

Cheers

Personally, I like hardwood for top - It is not a sound quality decision rather aesthetic. Wood also has a good acoustic, isolation and dampening properties. Arm-board...well, most guys recommend MDF for its properties. However to much MDF can cause sound to be "to dark/lifeless". But I guess it is the best way to go (safe).You could also try to make a 2 layer arm-board - MDF&Ply or wood. I like to experiment with different wood species. I love the warmth of wood and it may have something to do with my passion for woodworking.
I kind of know what you are thinking. But don't worry. It is normal when plans change. It happened to me more then ones. It is all for the better. Think positive - and whatever you are going to build will most likely be better then the shelf units at your average audio shop.

Mariusz