Choosing Sub-woofers. Please advise ASAP.

" Your speakers are pretty full range so you'll need 12 inch or larger to extend lower if needed at all.  Two are better than one for balance across the room. "

" @ mapman. I thought so too. That is my original idea but shaken up a little when spoke to the dealer. He suggested his 2 used 10" subs at super crazy discount....

Also the room size is OK for 2x 12" subs?"

Not true. If you buy subs with 12in drivers, the only thing you can be sure of is that your subs will have 12 in drivers. Are all 12in drivers identical? Better yet, if you have one of the drivers blow in your Wilson's, are you going to run down to your local Radio Shack for replacement? People may disagree with me on this, but I think the quality of the speaker is a factor in how it sounds. 

If you want to make bass, you can either move a large driver slow or a small driver fast. If all other factors are equal, there'a no difference. Not only that, a high quality 8 or 10 in woofer, can easily outperform a low quality 12 in unit. 

mb1audio02

If you want to make bass, you can either move a large driver slow or a small driver fast.

That doesn't make any sense. A driver's movement corresponds to the frequency it's asked to reproduce. If it's a pure 32 Hz tone, the cone will move at 32 cycles per second, regardless of the cone's diameter.

Well, the frequency (i.e., the period between when the derivative is 0) won’t change based on driver size but cone velocity will, for a given output. A smaller cone moves less air and has to travel further between peaks for the same output as a larger driver.

i’ve always understood it this way, but I’m here to learn so I’m happy to be proven wrong. ;)

cedargrover

Well, the frequency (i.e., the period between when the derivative is 0) won’t change based on driver size but cone velocity will, for a given output.

The "cone velocity" is the driver's frequency. If asked to produce a 32 Hz tone, the cone should move at 32 cycles per second, regardless of the diameter of the cone. It's simply not true that:

If you want to make bass, you can either move a large driver slow or a small driver fast.

The key is for a given output.  A cone can cycle at 40 hz, but the distance between stops (i.e. Where derivative is 0) will vary depending on the amplitude of the signal. A smaller cone has to travel further to move the same amount of air as a larger driver.  So a large cone might move 5 mm back and forth to produce a given output at a given frequency.  But a smaller cone might have to move 7.5 mm.  And do so in the same period of time to keep the signal at 40hz.  

If im wrong, show me the maths!  :)