Downfiring sub?

I have decided to down fire one of the two subs in a center consol box. The other will be facing foward.  My question is approx. how much space needs to be given between the sub cone and the floor?

I hope to begin the buils soon.

Thanks

The sub is capable of being downfired.  It calculates out to 2% sag, so I am good there. To SS, the Xmax is 16.48mm.  Almost all the posts that I have read have stated the a downfiring sub might be the way to go.  As far as how much space need to be left between the floor and the woffer I am still unsure.  I also dont know haw much space needs to be left around the sub.  T0 clearify the bottom ofthe consol will look something like this:                                                   

      /________I`````````````````````I____________I

With the sud being here ^

Or would it be better to put the whole consol on "feet"

Feet is the way to go...it opens up maximum airspace 360 degrees with only the small footprint of the feet blocking waves.  Allow plenty of room for max cone excursion...that's about it.  The sound waves will be forced out into space.  In the case of using a port, however, the space at the end of the port opening would have to be bigger (allowance for the proper function of port tuning).

My concern with such a setup as you described is that the two woofers are firing in different directions, which could muddy the sound with waves that cancel each other out when they hit at closer to 180 degrees apart than 0 degrees apart.  Would be akin to sometimes experiencing reverse polarity.  With it setup like that, experiment with reversing the wires on one or the other subs to see if they hit more powerfully together and in time with the mid drivers.  Chances are, though, if they are hitting at 90 degrees apart, no manipulation of the polarity would fix things.

But for the sake of your design, it's certainly worth trying and finding out for yourself if it will do the job.  Speculation and second-guessing is the easy part...the real test is the actual building and testing.  Good luck.

A pic I made for another subject but similar to this (I like to bring out old pics)...

...because I like illustrations.  But this is to show that these two woofers are firing at 90 degrees from each other.  Reversing the polarity of one of them still results in a 90 degree difference.

This is one up, one down:

...again, old pic drawn to show the difference in airspace in the boxes, but it works for this subject.  One of these could be reverse-wired and they would both fire in the same direction simutaneously.

And, of course, two woofers facing the same way and wired the same will fire simutaneously in the same direction.  Just said to finish the thought process...

So, knowing these things, you know what obstacles you would face if you faced your woofers at 90 degrees apart.

Thanks to everyone for the help so far.

I think I will just set both subs to downfire and leave about 2" from the floor.  Does this sound like a better situtation?