Building the Acoustic Frontiers Demo Room – Part III: Paint, Star Ceiling, Lights and Carpet
It’s been quite a while since the last blog update on the Acoustic Frontiers Demo Room (Part I, Part II). However I am happy to say that there has been a lot of progress, although the room is still not finished! The room is already ‘up and running’ in the sense that it can be used for music and movies but there are still some areas we are working on (acoustic treatment in particular) and a couple of key items that still need to be installed (blackout blinds, stretch fabric on screen wall, etc).
Today I am going to give a update on the interior decoration and fit out of the room.
Neutral wall and ceiling paint colors
For home theater use it is important that the walls and ceiling are painted a dark color in a non-reflective finish. A front projection screen works by reflecting light back towards the projector. Some of this light hits the side walls, ceiling and floor. Glossy paint finishes causes distracting ghosts and reflections to appear as the light is reflected from the wall back to the viewer. Flat or Matte colors reduce this significantly. Light colors also cause a reduction in perceived contrast. The best finish is flat black but that can be quite imposing when used everywhere. We recently calibrated a home theater in Dallas where the owner had mixed ‘sparkles’ into the flat black paint. He also had a heavy ‘orange peel’ type drywall finish. That combination actually worked very well and made the room a lot less foreboding. For our room however we wanted to make the colors welcoming yet fit for purpose. To this end we selected Benjamin Moore Andes Summit in Matte for the walls and Benjamin Moore Royal Wave (a midnight blue color) in Matte for the ceiling.
A twinkling fiber optic star ceiling
Another design element in this room was the inclusion of a Numinus StarTile ceiling. The Numinus ceilings are some of the best in the industry and create a twinkling semi-random or real world starfield using multi-sized fiber optic strands. See their gallery for a ton of great install pictures. The star ceiling provides a very low amount of ambient light and can be left on when movies are playing. From the factory the StarTile’s substrate is a 1″ thick fiberglass panel wrapped in Guilford of Maine FR701 Black. As anyone with a passing interest in acoustics knows 1″ fiberglass is generally bad news, especially when applied over large areas such as in a star ceiling. 1″ fiberglass, for example, only has constant absorption down to 800Hz or so. A 1″ fiberglass panel only absorbs 25% of the incident energy at 250Hz compared to 100% at 800Hz. This means that the reflected sound from a 1″ absorber will be ‘spectrally distorted’ compared to the direct sound. Ideally any fiberglass based absorber used at primary reflection points should be at least 3″ thick. This is to maintain constant absorption down to the transition frequency at around 250Hz where what we hear becomes dominated by the room rather than the speakers. To illustrate this take a look at the absorption curves for three different thicknesses of fiberglass absorber. The data is for Primacoustic’s Broadway panels but applicable to any fiberglass absorber:
So to make the ceiling a full range absorber we used furring strips and 2″ of OC703 fiberglass to space the star ceiling away from the drywall.
Color changing LED lights
Every room needs lights! In our demo room we decided on using a large number of 12V LED lights from NuLEDs. These LED lights are very shallow (<2″) which makes them ideal where sound isolation is a concern since you don’t have to penetrate your ‘isolation shell’ like you would need to with standard recessed lights. We used 4 high output white MiniCans over the seating area, 2 Mini-G gimbal spots and 9 RGB color changing SpectraCans. The other key advantages of NuLED’s 12V LEDs are the fact that they are controllable via RS232. This means that you can set individual RGB levels, turn the color loop on or off, dim the lights, create lighting scenes and more all from a universal remote control or your smartphone. A further advantage is that they do not require an electrician, since they are low voltage. The LEDs were mounted into the star ceiling by carefully cutting holes in it; a job that was made a little more difficult than expected due to the fiber optic strands everywhere!
And a Red Carpet!
For home theater use it is important that the floor be non-reflective to prevent ghosts of the moving image being displayed on your floor. Carpet, however, isn’t the best material to use from an acoustical perspective as it doesn’t have consistent absorption. Most carpets only absorb down to about 1kHz with any consistency. A better material is wood, and for a two channel listening room the optimum is probably a wood floor with a very thick area rug with underlay placed at the floor reflection points for the left and right speakers. For a mixed use room you have to make compromises, so carpet it is! To improve the absorption profile of carpet you generally want to use the thickest carpet you can find with a thick fibrous rug pad underneath. We chose a 100% wool carpet from Nourison – the Ashton Velvet in red. It has a very nice underfoot feel to it due to the high pile and the subtle pattern makes it much more interesting to look at than a solid color.