Time for an update.
Going back in time some after I had built the two subs I felt that the midbass impact was missing. My assumption was that it was in part due to the room and the cheap in wall speakers. At first I had tried adding the folded horns that did not work too well as I just got an interference pattern in my bass response because they were much closer to the LP then the 15's up front. Jake AKA Chopshop kindly offered to buy me a minidsp so I could test the active crossover with his SEOSR build when that starts so for now I am using it on my subs. With the minidsp I was able to add some delay to the folded horns and bring the phase in line with the Dayton. I also EQ'ed them both a little and added a 4th order 11hz highpass to the 15's.
After plugging in the minidsp something did not seem right. My measured FR was flatter then ever but the bass sounded dull and boomy, the dynamics were gone. I bypassed the minidsp and things sounded 100x better, I could not figure out the problem and it was driving me crazy. Then it hit me, I flip over the minidsp and what does it say Rev.A
I had been clipping the input. I pulled it apart flipped the jumper to the 2v setting I also dropped the receiver's sub output level some and turned the subs amp's gain up just for some extra added protection against clipping. Tried it out and everything worked great all the dynamics were back. Adding the two folded horns helped a lot with the evenness of the bass across the seating and flattening the FR. While they did add some midbass impact that I felt was missing I was still running the in wall and felt they where the limiting factor there.
Next step upgrade speakers. For now I did just the side surrounds and LCR, the sides are my MTG-06-OWS design which uses the now unavailable Aura NS6 and the DNA-150 on the EOS-6 waveguide. The LCR are an older design of mine dual 6.5’s under a Dayton 6x12” JBL-clone waveguide. These have always been one of my favorite designs and I recently switched the Selenium DH200E-E CD’s I had in them over to DNA-150’s and got a large improvement in clarity, smoothness and detail. Now I like them even more. Unfortunately like the surrounds the woofers used are also NLA. The center uses an older Peerless HDS and the L&R use the Klipsch Ultra 2 buyouts. The crossover are almost identical with the peerless having slightly lower sensitivity and therefore more padding on the CD. I think this helps lessen the tonal differences to the point where I can’t even tell they use different woofers. I do have a version in the works using woofers which are available which should come in just under $100 for the drivers and crossover. I think those will really push the performance you can get for the $.
The marks on the wall is from the JBL HTIB speakers that where up there before.
The center just sits on top of the subs in front but the L&R needed to be mounted to the wall. For that I just picked up some of the dual track shelving strips and brackets. I mounted most the track behind where the speaker sits which I feel makes for a much lower profile then a 90 degree angle shelf bracket would have been.
After I got them installed I tried them out with some music just running in direct mode and I could already tell things where much much better, even without the subs running the bass was impressive. I let MCACC do its thing then made my own measurements after to check up on it. It did ok with the speakers, I made some minor EQ adjustments to them though. The problem with MCACC it is the sub integration. It set the subs at 12’ which is technically correct but when measuring they don’t integrate with the mains that great. I feel that proper integration is a very important aspect in getting bass to sound correct. The mains are set to large and the subs to plus so there is a wide range where they need to play nice together, roughly 30 to 80 Hz. Over this whole range the phase response of the subs must line up with that of the mains otherwise you get an interference pattern between the two. This is what the individual mains/subs and combined response looked like with the default setting MCACC generated:
I did not like that one bit, two signals should add not subtract from one another. Unfortunately the phase control will not be much help over this large a range as it will only move the peaks and nulls up or down. When it is useful is when the range the subs and mains overlap is small say when the mains are set to small and the rolloff is quick so you can hopefully adjust the phase to position a peak over that range and be done. For the large overlap I need to use delay or adjust the sub distance setting in the receiver (same as delay). I started by moving the sub distance closer some and re-measured, if the pattern get narrower I am moving the wrong way if wider I am moving the correct way. After a few feet it looked to be getting narrower so I started moving the distance further away. Finally at 28’ I had what I was looking for:
The mains look like they contribute down to 20hz which is cool. I tried it out with some music and the rooms has never sounded better, the transition between mains and subs is seamless. I now have the midbass impact that I had been craving and it is awesome. I watched Avatar and the new Star Trek both sounded excellent. The side surrounds also work great, effects are not localizable at all which was a worry of mine.
Next up I plan on pulling out the in-wall speakers patching the holes and painting the walls and ceiling in that room black, the white ceiling just kills the contrast on the screen. I also need to figure out what I am going to do for the treatments, right now the walls are bare and it sounds great so I cannot imagine how much better it will get once I start to add some.
Who builds a sub and never tries it out, get to it man. 
