I debated whether this belonged in the construction forum or the acoustics forum, but chose construction. Hopefully I chose correctly.
I’ve been reading this site for months trying to digest all that I can before I begin work on a small studio in my home. This is truly an amazing resource that you’ve created!
My goals for my studio are fairly simple. I want a space where I can mix, and where myself and one or (at most) two other people could come and record. The mixing and recording would all occur in the same (small) room. We tend to play mainly acoustic, and some low volume electric guitar/bass. I live in a very quiet neighborhood where sound coming into my basement isn’t really an issue.
Based on the playing style and the neighborhood, and for the practicality of the small space I have, I’m inclined to *not* try and create isolation from the rest of the house. I am, however, worried about acoustic absorption, and creating a space that sounds reasonably good for not too much money. This, of course, is why I’m writing to you!
The space I have to work with is in my basement, which is about 2/3 under ground. The foundation is 6-8” cement. The floor is poured concrete. The previous owner of the house framed in a small room in the basement which, as near as I can tell, was used as a very large cedar closet. (The whole thing was lined in cedar particle board and shelving. It smelled like a giant hamster cage.) I’ve removed everything from the framed walls in that small room down to the studs (2x4 timber). Because of a furnace and the resultant ducting outside this room, there isn’t really anymore space to work with, so expanding beyond this small room isn’t feasible.
The dimensions of the room (from the foundation, ignoring the framing) are as follows
16’ 9” long
8’ 1” wide (from foundation to the framed left wall)
6’ 10” high (from the concrete to the bottom of the rafters) (low ceiling!)
The dimensions of the room (measured from the outside of the framed studs) reduces the room to this:
16’ long
7’ 6” wide
6’ 10” high
The walls, of course, are pretty darn parallel. Here is an overhead view of the room (the grid is 1’ squares for scale):
I’ve tried my best to do my homework, and this was my first guess at what I think I need to do to this space to make it have decent acoustics. Basically, I’m following John’s wall unit page (http://www.johnlsayers.com/HR/index1.htm) and filling in with corner, side, and rear absorbers. You will note that I am reluctant (out of laziness) to remove the framing:
After completing this drawing I thought some more and came to the conclusion that maybe I could use the space behind the faming (on the right wall) or in between the studs (on the front and back walls) for better absorption by simply adding in some proper insulation there. That also led me to think that then I wouldn’t need quite such big absorbers, which really take a bite out of the useable space in such a small room.
In this second drawing I’m also accounting for a large table that I already own, and I’ve tried to figure out best placement of things using the room mode calculator and making drawings of the “non-null” areas that result from those graphs. The white space is the area I’m trying to leave open for recording purposes.
My questions are as follows:
1. In general, is this a workable design?
2. On the left wall I am planning to do a *little* “isolation” work to try and block some furnace noise. My plan for that wall is simply 2 layers of sheetrock > studs/insulation > 2 layers sheetrock. I don’t expect this to be even close to perfect, only to cut down a little noise for those times when I absolutely can’t turn the furnace off. Will this work?
3. On the other 3 walls I’m open to suggestions for building techniques. Should I fill in fill in the space with mineral wool and cover in with cloth? Should I fill in it with pink stuff, sheetrock over it, and then leave the bulk of the absorption work to the absorbers I plan on building?
4. How many things am I not thinking of?
Thanks in advance for being such a great resource,
Jed Jorgensen
Portland, Oregon
P.S. That little brown square is a 6x6 beam that runs floor to ceiling.
Also, I noticed that the ceiling joists don't touch the siding - there is about a 1/2" space there. 
