The dual design of the chamber was necessary to isolate the subwoofers from the platform extension, and then to isolate the extension from the existing platform.
The subwoofer “inner chamber” is constructed of wood and fastened tightly together with glue and screws to prevent rattles and buzzes. All seams are caulked air-tight, furthering isolation properties.
The “outer chamber” – built within the airspace between the inner chamber and the platform – is isolated from the platform by using wood and concrete board.
After the two chambers were completed and the subwoofers installed, the space between the inner and outer chambers was hard-packed with insulation to add further damping. The top of the box was then sealed with two layers of plywood.
This article was republished with permission from ProSoundWeb.
This approach worked out very well, with the end result as predicted – flat and very smooth low frequency presentation, and the desired full-range overall output that keeps up with the high impact (pun intended) of the church’s youth services.
