I designed everything in Sketchup. Walls, doors, acoustic treatment and all the speakers (All 17 of them). I spent a couple years tinkering with the room and speaker design before cutting any wood.

The room is 15' 3"(4.6m) wide, 17'10" (5.4m) long and 8'9"(2.7m) high. It's in the basement, and somewhat disconnected from the rest of the house so sound isolation wasn't really a concern. Acoustically I was after something that sounded good for music as well as movies. I think it sounds great, but their's much I don't understand about acoustics, and I'm sure the experts would have done things differently...

I essentially built a room within a room giving me about 12" of space in which to stuff all the acoustic treatment I wanted. The lower parts of the walls are filled with fiberglass and covered with a random spacing of wood slats. The quadratic diffusors are made from 2" rigid foam which I sprayed with a couple coats of grey paint. Painting probably wasn't necessary but thought it might help to make the foam a bit more reflective. 

The 16" deep ceiling joists are filled with fiberglass and then covered in fabric. Suspended below the fabric by a couple inches is a repeating 13 root QRD diffusor. In an effort to make it a bit more interesting I shaped it horizontally to match the waveform pattern of a piece of piano music that I hope to be able play someday. 

Other than the ceiling diffusor all the room treatment is covered in fabric. For this I gambled and used the Fabricmate system. This was easily the biggest unknown of the entire project. I had zero experience with installing fabric, upholstery, or anything I could really relate it to so I was nervous for sure. For a variety of reasons I had to start on the ceiling - which is my mind would be the most difficult. Once I got the track installed I was amazed and how quickly the fabric install went. While corners were occasionally a challenge, the fabric tensioned nicely, with neat clean edges and corners. For once a project that was easier than anticipated with results that exceeded my expectations. I can't recommend Fabricmate highly enough. Excellent system and great support.

Deciding on a LCR speaker design took quite while, but what I really enjoyed was the fact that I didn't have to worry about what the speakers looked like. Glossy paint and fancy veneer didn't mean much when mounted behind a screen. This fact alone made building the speakers so much fun.

I had a DEQX unit which could easily be incorporated, but I really didn't want to buy a second DEQX for the center channel. I considered a MiniDSP but found a ScanSpeak kit at Madisound that utilized the exact drivers I wanted (had) which simplified things a bit. As is the L and R are fully active electronically crossed by the DEQX and the center is a passively crossed ScanSpeak kit from Madisound

Had read some things about large baffled speakers from Troels Gravesen that made sense to me so I incorporated a large curved baffle on the L and R channels. Given the ScanSpeak kit, I couldn't do the same for the center channel - less than ideal in terms of identical front speakers, but they do use the exact same drivers.

The mid cabinets are a bit unusual. I tried to copy the B&W tapered tube design. A stack lamination of MDF with differing size cutouts gave me the shape I needed. Between achamfer bit and lots of sandpaper I got fairly close to what I wanted. 

In addition I tried to isolate the mid driver from the cabinet. The Mids are mounted on a 5/16" threaded rod, that is connected to a piece of aluminum square tubing I epoxied the the rear of the driver. The rod extends through he back of the speaker where a thick dampening gasket/washer and finally a nut are used to pull the driver into place. Worked fairly well, but as for the longevity of the epoxy.... Time will tell.

The woofer cabinets are a bit simpler, although overbuilt. Cabinet walls were made from sheets of 0.75" ply that were laminated into 1.5" panels. In addition to internal bracing I also used threaded rods to mounts the drivers. This time however they were used as braces and to couple the from and rear walls of the cabinet - In this case, a #10 (I think) threaded rod was passed through the driver mounting holes and out the back of the cabinet. 1/2" EMT conduit was cut to fit snug between the driver mount hole and the rear of the cabinet. That way with a nut on both ends of the threaded rod, I could clamp the driver in place and essentially couple the front and read cabinet wall together. Over kill for sure, and less than elegant but really strong.

I used a similar mounting strategy for the dual opposed subs I built. In Front I used 4 Dayton UM18-22s mounted in 20" sonotube. In the rear I recycled the subs from my previous system, 4 ScanSpeak 23w's, also mounted dual opposed in sonotubes.

The subs are suspended from the ceiling by nylon straps so the vibration cancelling effect of the opposed mounting was essential. Amazing how well it works. The 18s can literally shake the room, yet with your hand on the side of the tube your hard pressed to tell if their on or not.

And just for sufficient overkill and chasing some low frequency db, I added a couple Dayton UM15-22s in the sidewall...

I wanted to use a pull out style AV rack something like the Mid Atlantic models, but sticker shock had be back in sketchup designing my own. In an effort to keep things cool the sides are open and rather than full length shelves I used two 3" wide boards, one for the front and one for the rear feet of each component. This allows heat to more easily move vertically in the rack. 

The hard part however is that the rack was to be install in foundation bump out that was initially intended for a fireplace. My AV closet was just 36" deep and 47" wide. Knowing that I needed easy access to the back of the rack, I decided to mount the it on a lazy susan and then on a set of wheels. I could now just pull the rack away from the back wall a few inches, and rotate it 180* for easy and full access to the back. Oh, and the rack in behind a bookshelf door - so when it's closed you it looks just the same at the bookshelf on the opposite wall.

The other fun feature of the room is the door. Originally access to the room is down a hallway that simply opened to the room. The opening was large, ~55" wide and 7' high. Acoustically I wanted a symmetrical space so I built a door with the same depth and acoustic treatment as the surrounding walls. It a MONSTER. Easily 200 lbs, 58" wide and riding on an offset pivot hinge that somehow makes the thing weightless. Stressed about building and installing this for months. The day it went up, and fit I seriously couldn't stop smiling. With the door closed it's not obvious where the exit to the room is - in the photos the door is on the left - the handle is a piece of aluminum L channel (painted brown) that also serves to hide the gap.

It was a total DIY project taking me about a year of weekend and weeknight/day off construction to complete (well maybe longer as I've still got a few things to finish). Thankfully I enjoyed the design and construction - that said, I'm seriously lookin forward to being done, and watching some movies.