We were living in a 100 year old house and recently moved to a newer, bigger house with a 42' L x 16' W x 8.3' H basement. I've been tinkering for months and finally have things at an intermediate stopping point.
At the front are four, DIY 4"x4'x8' Owens Corning Select Sound panels covered by black velvet. I glued two 2" panels together unfaced-to-unfaced to make 4" double faced panels, bagged them in fabric to keep the fiberglass intact, and offset on each corner to improve bass trapping. The velvet is stapled to some wood boards and screwed into the ceiling. On the L/R sidewall are 8 Monster Bass Traps from GIK (on each side, the two nearest the MLP have scatter plates installed to keep the room alive). GIK 244 Cloud mounted on the ceiling. All in upgraded Guilford of Maine Onyx Black.
And lastly, some GIK Gridfusers for diffusion (these were a total pain to paint, but really add a nice acoustic touch).
Things are sounding incredible, both in stereo and 7.1, and I believe I've achieved the right combination of diffusion and trapping. I'm still getting what I believe is a height mode at 125-150 hz, but it's much better than in the past. I do have a big bump at 20-25 hz. Here the "high" filter on the Rythmik plate amp came in handy. This moves the high pass filter up to around 30 hz or so. This has two effects: it brings the 20-25 hz bump down and it cleans up the bass since the woofers aren't tasked with playing quite so low.
-I'd like Jim to build me a "matching" center channel and stand to bring the center up a bit. I say "matching" because I don't think Exoticas are the right choice for a center channel. We're thinking Be tweeter, soft mid, soft woofers in a ported C7 sized cabinet.
-Update the surrounds to four NHT C3 Bookshelves on Black Friday this year. The current surrounds (NHT C1 and C2) are fine, but they do gloss over some details.
-Next year, new receiver and 4 or 6 NHT in-ceiling speakers for Atmos. Either going to be the Marantz AV8804 (if they ditch Audyssey and switch to something better), Lyngdorf MP-50, or Anthem AVM60. If Anthem releases a statement line I'll consider that as well.
-Of course the 65" plasma display is undersized, but projector and OLED tech is advancing so fast at the moment I'm going to wait until 2019 to update. Hoping we'll see 100" OLEDs at a fair price at that time. If not, projector it is.
-Swap out the single SB13 for dual SB16s from SVS.