Down firing sub tweeks

The bases made by Zmanastronony are what I was thinking. What are they made of ? What did you notice as far as an improvement ?

I used two 3/4 in birch plywood screwed together and put some 1/4in spikes underneath to couple to the floor.
The sound was more detail and less wooly. also, more gain and smoothness in presentation. I also put cones between the sub and the platform, it increased the speed of delivery.

Hi all ! I went to a counter top shop and they made me 3 16 x 16 pieces of granite for $60 . They are very heavy . Used one under each speaker and one under my amp . Might try another for the sub .

Was that $20 each for the granite? If so, that's a steal.

If you go with the base method, as I have, what I did was make the base a bit larger than the sub with slightly rounded edges at the top. After that, put a round spacer with a hole drilled in the middle between the sub and the base at the corners then get some large brass spikes with an internal thread in them. What you have to do is cut some threaded rod that has the same thread pitch as the spikes internal thread and the subs inserts and use that to tighten everything together. This way the sub and base is all one unit and about 15 pounds heavier. If you use granite, you'll have even more weight (mass) which will keep the sub more stable in the carpet.