So It`s Ok To Mix and Match Ported and Sealed Subwoofers ??

millercarbon :
  If you want to see what DIY with freebie cabs can look like, my system is now posted.

 Very NICE setup Chuck !!  The subs look beautiful

Yes well that is real rosewood veneer, and added about $500 compared to painted MDF. Just don't look too close, it will quickly become apparent these are not at the same level of professional finish detail as say the Audiokinesis Swarm. Not that I couldn't have done that, but everything's a matter of time and effort. This I feel is the right balance for going in my dimly lit listening room.
Rest assured they sound way better than they look!

Update !

I decided to just  add two more subs.
I bought a pair of HSU ULS-15 mk2`s they are on their way from HSU right now.
They are a satin black..to get the Rosewood finish like Chucks it would have been an additional $300 or so unfortunately :(
They are supposed to be a very musical sub from all that I read and that was a huge part of my final decision making.

So I`ll have my 15" Revel sub plus the two HSU 15" `s and a 10" powered sub all sealed versions.
I`m hoping the subs will do well enough in my 3800 cu ft room....will see 

Hello scm,

     Excellent, from what I've read, the HSU ULS-15 mk2 are a very good choice.
    I suggest you first setup and audition a custom 3-sub DBA system in your room, using your 15" Revel/with Dayton amp and your 2 15" HSU mk2 self-amplified subs.  
     It's important to position each sub optimally in your room.  I think using the crawl method, starting your search at the right front corner of your room and moving counter-clockwise around the perimeter of your room, should be sufficient for positioning each sub but you're welcome to use a more sophisticated method if you have the equipment and know how to use it.
     Once all 3 subs have been optimally positioned, proper setting of each sub's volume, crossover frequency and phase controls are the next critical steps.  Ideally, your goal is to have the volume of the subs match the volume of your main speakers and resist the urge to turn their volume up too high, you only want the subs to be active when the musical content demands it.  I've found it useful to set the volume as low as possible with the bass still sounding powerful, dynamic, detailed and natural.
     For the cutoff frequency settings, I suggest running your main speakers full-range and initially setting this control on each sub at about the rated bass extension frequency limit of your main speakers.  You can then adjust this setting slightly upward and downward until each sub is perceived as seamlessly integrated with your main speakers. 
    For the phase settings, I suggest you initially just set each to the position the bass sounds best to you.  I don't think this setting is as critical as the other 2 but I can detail more precise methods of optimally setting the phase on each sub if you'd like.
     I'm more than willing to further assist you when your new subs arrive if you'd like.  Just let me know on this thread or PM me.

Tim

Tim..that looks like a good plan to me !
Thanks Again   
Steve