@millercarbon The mineral oil is going to do the job, good idea. What
quantity you used for your box?
No idea. Too long ago. Just pour and mix, pour and mix. You're going for not even damp, just barely enough so the stuff holds a shape with no dust.
I am considering between four footers,
ASC or springs. I think it`s the best not to leave gap between the two
boards or am I wrong?
Okay there's a couple things going on. One is the sand is adding mass and damping, but almost no stiffness. Its the board or whatever goes on top that gives the required stiffness. Otherwise without that its like sorbothane, horrible, sucks all the life out of the music.
Sand and mass stops most vibrations but not the highest amplitude lowest frequency ones. Springs will work for that. But springs bounce. So if you do have something like people stomping around you still need something to control the springs. They are at best just one more tool.
I am keeping the board since it`s a really nice Shun Mook maple board, I
really like it.
Great. So keep it. I would suggest trying it laying directly on the sand. That way you get a little of the maple sound you like but not as much and with more slam and dynamics. But its all a balance. The more you try the more you will see.
I have tried granite, I think it was "ringing", but I
guess I`ve messed up something.
No, you're right, it rings like a bell. Its awful. Mine is on packed sand inside a massive concrete sand box and that kills a lot of it. Tap it and instead of ringing its a short sharp 'tink'. Which is not as good as "tunk" but way better than "tinggg" which is what it does with no damping. Then there's multiple layers of BDR and even so I have to use a couple different things between the granite and the BDR. Its a pretty good balance, super dynamic and detailed, and I have got it down to where no one ever even notices any ringing. In fact the verdict is "audiophile nirvana". Read the last system comments. But that's the thing about striving for perfection. I would try something else if doing it today.
My phono stands on 5" MDF (6 layers
glued and veneered) and thinking about to DIY it`s final sandbox soon.
The bottom and the walls of the boxes are 2" MDF, but If I thought It
would be good to upgrade later to real wood. Maybe I should drop the
idea :) What footers would you use?
Yes I would drop the wood idea. Unless you really like it. Always do what you like, never mind anyone else. All the wood species I tried imparted a very characteristic sound. I tried them because other guys thought they sounded great. MDF has a much more neutral character. But then its also a tad less stiff, therefore a tad less dynamic. Always the trade-off. Anyway if you want it to look nice simply cover with real wood veneer. That's how these subs are finished, rosewood veneer.
https://systems.audiogon.com/systems/8367
Mine is from
https://www.veneersupplies.com/categories/Raw__Wood__Veneer/Wood__Veneer__A__-__G/ and I used the one with adhesive backing. Cut, peel and stick! Could hardly be easier and looks terrific!
(I know you could just scroll up for the link to my system. But someone complained about me posting links to my system. So now guess what? Even more links to my system.)