Thanks Smokarz. It's really easy to do and cheap. I bought the 4" black PVC pipe from Lowe's, cut a 4.25" hole in the double baffle with the Jasper jig and my router, glued it in with some Gorilla Glue (which expands to fill in any gap), then used a big 45 degree chamfer bit on a few passes for the bevel.
It's hard to explain what I'm looking for but I'll try: I love the sound as is and my system runs almost flat even before eq, but I would like to capture a bit more warmth from music that I'm not getting from the Gjallarhorns with the mains. The SDX15 subs that I had before were so musical - perfect in my opinion, at least for me, so I'll see if I can blend them in. I actually just now bought another SDX15 from a guy on HTS, so I will try one in each of the L and R. I prefer how the SDX15 sound sealed and there is only room for sealed in these cabs as long as the TD12m is sealed. The LCR will all be sealed with my new idea, only the center will not have a sub in it. If it doesn't work out, no biggie, I'll stay with the 45hz ported design. I like building speakers till I'm blue in the face.
Last edited by d_c; 07-27-2014 at 02:13 PM.