Desert Sunset Theater Build - Page 12

They are DIY Bass traps. I built them for my last theater room. 2 of the traps are made with the Roxul 60 Rockboard (6 lbs cubic foot) and 2 are Roxul 80 (8 lbs cubic foot) cut into triangles 24x24x33 (2x4 sheet cut into 4 triangles) They are covered with Guilford of Maine fabric. I could not find OC703 in my area so I used the Roxul stuff. I would use it again even if I had a source for OC703. It is significantly cheaper than the 703 - the only disadvantage is that it is not quite as rigid and twice as heavy.

The roxul 60 have very similar absorption as the OC703 panels everyone uses. I made the other 2 out of the 80 because it has a bit better low frequency performance. I found the specs here:

http://www.bobgolds.com/AbsorptionCoefficients.htm

In my old theater I placed these in each corner of the room, so I only have 4. I also have some 4" thick and 2" thick wall treatments still in the storage room. The treatments made a huge difference in the room. In my current room one corner is occupied by a door so I'm going to try and get as much bass trapping as I can in the soffits.

I picked up the 4x10 MDF sheets that I special ordered and started laying out the star ceiling panels. My truck only has a 5 foot bed so driving home with 5 -4x10 sheets was interesting. First started with the curved portion at the front.



Then lifted it up to test fit. Looks easy in the pics but it was 3 hours of work to get to this point. Had to make a new template for the curve on the front.

I also did some work on the hush box. Ran the fan duct and conduit and installed the electrical box for the powerbridge. All the initial wiring will be run outside the conduit leaving the conduit open for future expansion.

I'm doing the same thing. This is the thermostat that I am going to use. I think I purchased this at Amazon.



Here is the fan I am using. I need to rig up a way to hook up the vent to the intake.

The thermostat will install right in the box. It does not have a remote sensor.

The illuminator for the star ceiling arrived.

Started laying out the stars onto the panels. I also cut the joints for the biscuits to keep the panels aligned when on the ceiling.

I really agonized about how I was going to mount the panels. I experimented with some aluminum z-channel like others have used but I was afraid that they would rattle when the subwoofers get going. I experimented with a few other things but then decided that each panel would be screwed around the perimeter and then the part that is in the middle of the ceiling would have a bolted on bracket that will be screwed on the side so no screws will be visible in the center of the ceiling. The first panel is screwed with 1000lb rated spax screws on all four sides the next panel will be screwed on three sides and then nailed with a nail gun to the bracket on the other panel. I will also have supports that will be nailed in the center of the panel. The nails around the perimeter will be covered with a moulding and the light tray.

I did a test fit on the first and second panel. I wanted to make sure the first panel was square so it did not throw off the rest of the panels. It was a little off the first time but I was able to square it up so the second panel fit better.

Today managed to get all the stars laid out on the panels and the holes for the fibers drilled.

The company that I got the star ceiling parts from (FOSI) recommends 3/4 MDF. I thought about other materials or thinner panels but wanted something that would stay completely rigid (no sag) and would also be strong enough to put the biscuits in the edges. I debated using rigid foam, and I also emailed a company that made composite lightweight honeycomb panels that were filled with foam but structurally strong but I never got a response back. (I'm sure this would have been an expensive option though). I think something like foam would work for a smaller area but for a 20 x 10 panel you really need something strong that you can tie together well. The MDF was tried and true and has been used by others so I stuck with it. At first I was a bit worried about the heavy panels but once I attached the first panel I could see this was the way to go. It is completely flat with no sags.

I'm also really glad I did not go with a thinner MDF panel. I think it would have forced me to go with the z clips because the bolts would not have had enough material to support it.

I'm not sure if I mentioned this previously but the panels will be wrapped in fabric.

Wow that must have been a project! I planned to use the lightweight MDF that FOSI recommends. It is supposedly 30% lighter than regular MDF. It was hard enough for me to find 4x10 sheets let alone the lightweight panels. I called every place within 60 miles looking for the lightweight stuff. I ended up with just standard 4x10 MDF and it is incredibly heavy to move around especially with one person.


On the way home with the MDF, I had the sheets strapped into my truck but with 5 feet of the panels hanging off the back of my truck they seemed quite flexible

I'm still waiting for fabric to arrive so I have some down time where I cannot work on the star ceiling. I decided to play around with modifying the FOSI illuminator so that the stars do not shoot so often. As it stands now the shooting stars go off with each rotation of the wheel, which is less than a minute to make a full revolution. There is little slot in the wheel that passes the line of fibers for the star. I thought I could mock up a gear that would cover the slot most of the time but the gear would move one cog with each revolution. I made the gear out of lexan plastic and covered the gear with aluminum tape except for a tiny window that lines up with the window on the wheel. I do not have much in the way of fabrication tools so it is a little crude. I'll have to cut down the axle because there is not much clearance in the box, but it appears to be working as I intended.



This is what the gear looks like mounted to the wheel.





This shows the slot in the wheel that lines up with the window on the gear.

I made two lexan gears last night and started cutting the axle and my dremel tool gave out so I could not finish. I guess drilling 900 holes for the star ceiling and this project were just too much for the dremel. I'm going to replace the brushes in the dremel to see if that works.

Moggie - I'm sure with your milling skills you could come up with something much better than my crude mod.

I took the dremel tool apart and it had seized bearings so I bought a replacement. I guess drilling the 900 or so holes for the star ceiling was more than it can handle. This is the second dremel that has died on me and I am not a really heavy user so I tried a different brand this time.

I decided to give the proxxon rotary tool a try since it has pretty decent reviews. It only goes up to 20,000 rpm vs 30,000 for the dremel but on my first use I can tell it is much more powerful and operates smoothly and quietly. It does not slow down under load like the dremel did so I think the RPM's are actually better when doing actual work with it. It is a bit more expensive than the dremel but seems like quite a step up in quality. The only thing I really do not like is where the power switch is located - that will take some getting used to. I really like the variable speed wheel dial.

Finished up the mod to the star ceiling illuminator last night. Here are a couple shots of the detail on how the gears were terminated.

I also had someone ask what parts I used for the gear. I went to a hobby shop and found some suspension parts for an r/c car that worked well. The rods were 44mm long (cut down to about 15mm) and 3mm diameter. I used a 1/8 wheel collar for model airplanes to terminate the other end. It was much easier to get on with the collar than using a second clip ring. The gear was just cut out of a peice of lexan plastic i picked up at lowes. Delrin would work better but I did not have to go out of my way for the lexan.

Made some progress on the theater but not much to show. I did get the illuminator installed in the soffit. The normal illuminator from FOSI is 12x12 which would not fit in the soffit. FOSI was very helpful and made a 12x10" illuminator for me that fits perfectly in the soffit. This is also a new LED illuminator. I wanted the metal halide illuminator because I thought it would have a warmer light but they said that they apply a correction filter to the metal halide lamp that gives it a cooler whiter color that looks more like stars. The LED light is more naturally cool. They did give me some extra filters that I can use to make the LED light warmer if I want.

The other advantage of the LED is that it is dimmable. We discussed dimming the LED and he said that they would have to wire it with two plugs so the motor is not dimmed. When I placed the actual order I forgot to mention this so it only came with one plug. I re-wired the box so the the lamp will connect to the graphic eye while the plug will be wired to a remote on off switch. You can see the the extra wire on the left side of the box for the lamp. Incidentally while drilling the hole for the wire, i used the new rotary tool to smooth out the aluminum hole. Started off fine then the tool slowed down, then died with a puff of black smoke coming from the inside. Not too impressed with it breaking down with about 10 minutes of total use, but while it did work it was nice and clearly better than the dremel. I'm now debating on whether to exchange and try the same one again (hoping mine was just a fluke) or get something different. I do not seem to have very good luck with these rotary tools. Maybe I should move to an air powered die grinder.

Fabric for the star ceiling finally arrived so I got the first panel installed. I lifted the panel onto the drywall lift by myself and bent over some of the fibers. There was enough slack that I was able to pull them out further and can still cut them off above the bend, but I'll get some help to lift the panels this time.