Down firing sub tweeks

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.

I do this with my Rel Strata III down firing sub. I flip it over so it is up firing, put a nice thick piece of wood on top of the now upward sitting feet (I use a large 1" thick maple cutting board) and put something heavy on that. I also recommend getting it out of the corner. You will have to turn it up a bit louder but with both of these changes you will now have something that is absolutely faster sounding with better overall pitch definition.