Home Theater Project
This is a chronicle of construction of our home theater.
We hired Randy Neilsen to do the construction for our home addition project. Randy is an expert craftsman and he's always there when he says he'll be. If you're in the Sacramento/foothills area and need some of this kind of work done, check with Randy. He's in the phone book as Neilsen Construction. His work included everything everything to get the house done with completed exterior and interior finished up to drywall installation. I would do the interior trim and finish electrical, lighting, and plumbing. I also did the demolition of the old deck which was where the addition would go. And of course I would do the home theater... This pic was taken in May of 2005. Rain was on and off. Mostly on when I was doing the deck demo.
August 05 and Randy was just about finished.
This is the upper level addition which adds on to the existing living/family room.
Directly below that is the home theater. Electrical boxes are for speakers, subwoofers, wall lighting, ceiling soffit lighting, and electrical plugs. Yes, a window. Just a hedge against future uses for this room. It'll be covered. There's also a sliding glass door to your left in the pic which will need a blackout system.
In the wall to the right side I roughed-in an opening for an equipment rack. It opens on the other side into a closet underneath the stairs and this will allow good access to the electronics wiring. All the speaker wiring comes from here (you can't see all the boxes behind the insulation.
The projector mounts behind the rear wall. The room is 20 ft front to rear, so the image will be 120 inches wide and 67 inches high for a 16:9 aspect ratio.  This image size is pushing the limits for the InFocus 4800 projector's resolution. But, the 4800 will eventually be replaced... More on the speaker/subwoofer/stage design later.
Sheetrocked with a smooth finish on the projection wall.
Back to the right wall. Equipment rack is the tall opening to the left of the door. The smaller opening is a place for a small wet bar sink.
The rear wall. The opening for the projector is at the ceiling height. Behind that wall is a storage area. That's where we will access the projector. I ran 2 1/2" PVC conduit from the equipment rack over the door (left side of pic) and into the storage area. This should allow me to run component video cable and in the future, be able to replace it with DVI or HDMI. Opening below the projector aperature is a shadow box for displaying...movie-related items. Sliding glass door to the right as previously mentioned.
We're now into January 2006...Close up of the projector window.
I made the projector mount out of the same plexiglas material used for the window. Two plates. One for a way to tie into the projector and the upper one to provide for tilt and roll. The lumber is to mount the whole thing to the ceiling joists.  BTW, the projector is an InFocus SP4800. It was replaced by the InFocus 4805 which now has been replaced by a newer model. But all are very similar 480p projectors and in the $1000 price range. If you're looking at buying one, there are more and more becoming available and it won't be long before 720p high def projectors are available in the under $2000 range.
A quick test shot -- image from Star Wars Episode 3. Graniness in the pic is from my camera. The image looks very good and with this widescreen version of SW3 shown at this aspect ratio, screen door effect only becomes noticeable at around 10 ft. With the rear row of seats at 16 ft. it should be fine and possibly OK for a closer row at 12 ft. or so. The limitation of the SP4800 projector is the visibility of "screendoor effect" when viewing at close distance. Depending on the source, with this projector, I can start seeing SDE at around 12 ft, which is 1.2 x screen width. My rear row of seats in the theater will be at 16 ft. So, the next row closer to the screen will be right near the 12 ft.
Now on to the trim and finish work for the theater. This is my basic concept for the screen/stage area.
A top and front view. Some sort of curtains will cover the main speakers with grilles over the subs. Problems with this setup will include the wall boundaries around the main speakers with potential for bass boominess and the placement of the center channel near the floor and closer to the listeners than the mains. Hopefully my processor will be able to compensate for some of these problems. It might be possible later to find an acoustically transparent screen and put the center speaker behind it.
Problem is, this is what it looks like now...
Here's what I plan to use for the audio side of things. The room is set up to accomodate a 7.1 surround system with speaker jacks in the walls/ceiling for left, right, center, mid-left, mid-right, rear-left, an rear-right speakers, and a subwoofer line level jack.
The main L/R speakers are my dB717TL tower speakers which I designed and have developed over the last five years or so. The DIY design for the dB717TL and the other speakers is on my web page at http://users.d-web.com/dbrown/speakers/speakers.htm This speaker is a transmission line design, about 4 ft. tall.
This is the dB717TLC center channel speaker. It uses the same drivers as the main speakes and is also a transmission line. The woofers and tweeter are arranged on the baffle to provide a more consistent dispersion pattern across the listening area, hopefully no hot spots or nulls.
The wall-mounted surround speakers are selectable dipole/bipole designs. There is a switch which reverses polarity on one of the tweeters to provide a more diffuse sound field. Currently, I have only one pair of these. One more pair will be needed for the mid-surround left and rights. These also use the Dayton 6 1/2" woofers and Silk Dome tweeters. My plan is to upgrade them to using the same RS series woofers and tweeters to provide a closer tonal match to the main and center speakers. The design concept for these as well as my overall hometheater audio concept is at my page, http://users.d-web.com/dbrown/htdesign/htdesign.htm
I'll be using two 15" subwoofers. They'll be in sealed enclosures on each side of the "stage". The drivers are SoundStream SPL170s -- basically car audio drivers with dual 4 ohm voice coils -- and they are designed/optimized for high output, SPL competition, as it were. These may not be the best for home theater, but I have them, and the response simulations I've done show that they should produce an F3 of 50 Hz with a Qtc of 0.61 in 2.5 cu.ft. I think, with their corner location the in-room response will be closer to 30 to 35 Hz. If these don't perform like I'm hoping, I have a couple of other 15s which don't have the power handling of the SPL170s, but will go almost an octave lower in a similar size enclosure. The WinIsd plots at the right show these drivers in the same 3.0 cu.ft. box -- just for comparison.
But...on the other hand, I hate to lock into not being able to get the lower extension available with a vented design for the SPL170s. In a 3.14 cu.ft. enclosure tuned to 31 Hz, the F3 is 33 Hz. And...using that same enclosure with the ports blocked, I would get a sealed alignment with a Qtc of 0.57 which is close to a Bessel alignment of 0.577.
Just out of curiosity, I looked at what would happen if I blocked one or two of the ports. With one port blocked, the response actually extends lower below F5. The vent velocity is up to 0.08, but still acceptable. Tuning frequency is 25 Hz. With two ports blocked tuning is at 18 Hz and the vent velocity is much higher -- probably beyond acceptable limits.
So, I ended up with the design at the right. Three 3" diameter ABS plastic ports, 16 1/2" long keep the vent Mach low (0.3). Double 3/4" construction with one brace. The vents are on the top rear of the enclosure because that is the only spot available given the location of the boxes in my setup. I could have placed them on the front of the enclosure, but it would have had to been significantly taller or wider and that doesn't work well with my design of the screen/stage. I elected to use particle board rather than MDF for the boxes. MDF dust is just getting to be too much to tolerate, especially in my workshop area inside the house. Plus, particle board is cheaper -- $14 per sheet versus $22 for low quality MDF.
In the meantime, work has been done on the equipment rack and the display box. The rack should be able to hold 7 or 8 components. Still need to make a door.
This is the back side of the equipment rack which opens into the storage space under the stairs. You can see the speaker, sub amp, and coax/TV plates on the wall.
This is the display case at the rear of the room. Will have glass shelves.
June 2006. The subwoofers are finished. This shows a setup with the speakers in their approximate locations. Although the room needs alot of work to dampen reflections, the setup sounds pretty good. Amazing, in fact, with movie soundtracks. The two 15 subs really shake the house!
Here's the equipment rack with 7 amps, Outlaw 950 processor, satellite HD receiver, and DVD recorder. Still needs door.
Rear of the rack. Lots of wires.
The dB1661 di/bipole right rear surround.
And the left rear.
August 2006. Equipment rack now with door. Painted sage green.
Opposite the door to the under stairs closet/equipment room, we had framed a closet opening. 24" wide to be used for storing dvds, etc.
September 2006. I added a box which hangs on the door to allow more storage. It's the only way I could think of to add more storage. I thought of a rotating lazy susan type arrangement, but it would have been too small to be able to turn.
October 2006. The proscenium is now framed up. The speakers will be covered with cloth on frames to snap in place. The horizontal panels below the screen will allow access to the center channel and the power plugs for the sub amps. There will also be a small stage in front of the center channel -- a semi-circular shape with a diameter of around 8 feet and about 7" high. Almost ready for paint and carpet and trim work. I really want to stop using the theater as a workshop.
By the way, I looked up the word "procenium" and this is what I got...
Here's one of the reasons the theater isn't done yet. 3 cords of wood needing to be cut, split, and stacked.
March 2007: Some progress. Removed construction tools (radial arm saw, compressor, etc.) and painted walls. Ready for carpet.
Another shot of the east wall. The statue is a family piece crafted by a friend of my dad in honor of a Navy pilot killed in Viet Nam.