Saturday, September 08, 2007

A Room In A Room

I have begun construction and assembly of the new surround mounts and other parts for my Home Cinema. As I am renting, I am not allowed to mount the surrounds to the walls, and until now, I have being using speaker stands. The projector has also being mounted in the EQ Rack which, whist it works, is far from ideal due to it's fan noise.

So I designed a Room in a Room [partially inspired by the displays at CEDIA] which allows me to mount the surrounds above seated ear height as well as hang the projector from the new inverted Projection Station.

A Plan View
Shown in plan, the Room in a Room consists of several elements bolted together. The design can be easily disassembled and stowed if I need to move, and then re-assembled later. The design is flexible so modifications can be easily made for the future should I need to change anything.

The main parts are the Projector Station, the Surround Mounts, the Stage and Screen and the EQ Rack.

The Projector Station
The Projector Station consists of two suspended platforms that have threaded adjustments for precise alignment of the projector with the screen. It also features the Sled for the Aussiemorphic Lens attached to the main base plate with two bolts.

The Projector Station with Aussiemorphic Lens
The Sled Mount is simply attached with two bolts extending up through the Projector Station. I drilled the holes slightly too small for the bolts so that they had to be screwed into the sled. This prevents them from falling out when I remove the Sled from the Projector Station. I have used wing nuts for quick handy attachment and removal of all parts. The projector is mounted to the Perspex plate by four bolts [and wing nuts] that extend up through the main plate of the Projector Station. This allows for precise adjustment of tilt across two plains allowing it to project nice level images.

The Projector Station sits in a cradle made from aluminium angle [I've used an L but the diagram shows a U profile] to allow easy movement forward or back to optimise the throw. As the Projector Station is inverted, I have removed the springs that were installed originally for shelf mounting. If this design was to be used in a shelf mount, I would not use the springs, but rather 4 additional nuts and washers under the Perspex plate. I am considering replacing the Perspex plate with an second piece of the laminated 16mm MDF board.

Surround Mounts
Three mounts each 2300mm x 1200mm are connected by a cross brace that also holds the Projection Station.

Left Surround Mount
I will add acoustic treatments to the lower half of each mount. The frames are built and can be lifted off using the same track that hangs the speakers. I was originally going to use foam, but have since found a dense fibre material that is not fibre-glass. Each frame will have black speaker cloth stretched over and stapled to the rear.

The Back Surround Array
The end result will see the raw MDF painted in Pompeii Ash Suede Paint to match the surrounds. I would have liked to space the Back Surrounds just a little more, but due to the restrictions of the room [there is a door just beside the RBS speaker] I have been forced to compromise. I have listened to several movie soundtracks and their placement works well enough.

Stage and Screen
There are four parts to the front stage and screen consisting of the Screen Rig, the screen stand, and the side masking system.

The AT Screen
The new AT screen now sits on top of the stage. The stage has already being painted in Pompeii Ash Suede paint, but the frame for the acoustic treatments needs to be painted black to match the other three. The side panels should be ready soon. The screen material was attached to the front because the screen is curved, so a cover masking frame has to be added.

Taking Shape Now
Both the side panels and the screen frame have been installed. An AT drop down Side masking system is still to come as is the top plate. Next I will paint that timber frame for the acoustic treatments below the screen and cover them is AT cloth.

Some Screen Shots
It is starting to look much better. I actually adjusted the prisms whilst the lens was inverted. I backed out the three bottom screws just enough to allow the prisms to move, then whilst the lens was in the light of the projector, was able to perfectly align the image to the screen.

The Back of the Screen Rig
The key to the best sound staging is to use three identical speakers that are all mounted at the same height and an AT Screen certainly allows that. Since this shot was taken, I have also added a small rail under the back of each LCR to provide a slight tilt down which seems to have improved the sound at the seating location. I used the same profile rail that I use for speaker mounting to allow addition material to be placed in the groove should the speakers require further tilt.

EQ Rack: The EQ Rack currently resides in the back of the room. Originally it was centred, but is now in the left rear corner. [Pictures coming soon]

NOTE: I will update the text and add photos as this project progresses...


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