Where to begin?

FTW-21s are definitely something, but they pretty much have to be used in EQ'd alignments with tons (3kW @ 4 ohm or greater) of power. So you'd absolutely need to factor in higher-end amplification and equalization too. And honestly, it wouldn't necessarily be the most efficient use of money, although it'd be really cool. It's just that as budget goes up, you could probably do six to eight of the Dayton or Stereo Integrity 18s sealed and a lab gruppen clone. Multiple Sealed Subs are pretty much the "ultimate" in infrasonic performance, while the additional sources serve to further smooth out midbass performance.

 

Sounds like sticking with the Daytons is indeed the way to go then. It seems to me that in order to reach the performance level we were discussing earlier via a sealed sub would be substantially more expensive than the large vented path. Although I am not looking to skimp in this project, I'm not made of money either. SO it seems to me that the safest course for me is to keep it "simple" and stick with a pair (maybe two pairs) of large vented subs.

 

Well, this weekend, I'll be heading to Lowes in order to purchase the MDF to start building these guys. Is there any compelling reason I would want 3/4" over 1/2"? the 3/4" costs more, weighs more, and will result in a slightly smaller interior volume. It is, obviously, going to be a bit sturdier though. Is this one of those things that I am over-thinking? Or is the extra sturdiness and mass going to be a benefit down the road?

 

I have 2 martysubs I built with the rss460s and I can't imagine that 1/2 Mdf would be a good idea. I did the 3/4 mdf and braced the heck out of it. Those Daytons are no joke. Make sure you use a double thick front baffle too.

 

The 3/4" MDF is not sitting in the work-space. I've cut the outside pieces so that when they are assembled, I'll have a cube measuring 32" on each side. It is my understanding though that the vent/port needs to be specially measured and shaped for the sub to perform acceptably. So, before I go joining the sides, I want to make sure I get a proper design going for these subs.


What is going to be my best tool for determining the specifics for the interior of these subs?

 

You may want to check out the martycube over on avsforums.http://www.avsforum.com/forum/155-diy-speakers-subs/1564457-martycube.html#/forumsite/3207/topics/1648673
There are 3 or 4 versions with different size cabs that are in the size you are looking at building. Cut lists for the cabs and port length for tuning. They are pretty simple to put together and have been giving folks excellent results.