Thank you Skirge01, your contribution is most appreciated.
As for the projects themselves, I've already mentioned the acquisition of the SpectraPLUS RTA tool
, which we're in the process of learning to use. We discovered that when SpectraPLUS is recording or measuring real-time, CPU usage is pegged at 100%. We did not realize this till after the Shuttle P4-2.56 system crashed and restarted after about half an hour of recording. We suspected software bugginess until the CPU load was noticed. Then it dawned on us that maybe a Nexus 92 fan at 5V might not be enough cooling for long stretches with SpectraPLUS. The CPU most likely overheated. For now, a quick 12V fan switch will be added, as much of the recording takes place in another room where the Shuttle's noise will not intrude... and later, an upgrade to a more powerful computer with better cooling (but similar <18 dBA/1m noise).
A 1" ACOPacific
measurement mic is being purchased, to work with SpectraPLUS. This is a ~$2000 tool of super caliber with ~10 dBA self noise. More details when we have it in hand and working -- probably near the end of this month.
Finally, the room. Over the weekend, I discovered the web site of a Toronto store dedicated to home recording studio gear and classes. Revolution Audio
built -- or is in the middle of building -- a room to contain the noise of drum practice! They wrote about it.
The techniques they employed are very similar to what we're planning here. The walls and ceiling are pretty much what we're planning... but the neoprene rubber used as dampeners for the floor are new to me, and I've got an email out to them asking more details.
The walls will be made of QuietRock
(8x more sound blocking than oridinary drywall) and steel studs, with Bonded Logic's Ultra Touch
recycled cotton batting (85% from blue jeans!) in place of fiberglass insulation, which is nasty stuff. The same material will be used for acoustic damping to eliminate echos inside the room -- this is difficult to explain, but you'll see and read about it as/when it is done.
The floor will "float" on the concrete cement foundation, then the walls will be built atop the floor, without touching any of the existing room's walls (a 4" gap is planned) and the ceiling will sit atop the walls, again without touching the existing room's ceiling. There will be double doors, both carefully sealed with neoprene rubber seals. No openings of any kind will be in the the room when the doors are closed -- it will not be safe to be in there long.
The estimated cost of the materials for the room is something like $8000 right now, higher than the $5-6000 I originally anticipated. This doesn't include any labor cost. I will be doing a lot of the work myself, Rob (my bro in law) will take charge when the work gets going (he's been involved in construction for a long time), and we hope to have one more helper for a few days. Maybe this can be a volunteer.
The room building will probably not start till close to the end of May. I have a conference in SF to attend
till past the 21st; it's clearer sailing after that, so we can start and finish quickly, hopefully in just a few continuous days of steady work.
Right now, the big question is whether we should build in the attached garage or the main test room in the house. The latter will probably be a touch quieter, but building in there is a much bigger challenge. In the garage, the inner chamber can be built at one corner, then two more walls added around it. This should be a much more straightforward procedure, as we won't be working in the confines of a room that's only 4" bigger than the one we're building. The additional walls will cost a bit more $, tho. The main question is whether it can be made quiet enough. We will decide after Rob goes over both option very carefully.