the listening room: "golden ratio"?

Hi Joeb. I am a bit late on this one, but thought it worth adding that the Golden Ratio is a way of fixing the natural problem of parallel walls and ceilings parallel to floors. But if you are building a separate unit (ie. your garage with room over the top) then you can do better still by having the room boundaries curved or just not parallel. You still need to do some maths about nodes, but risks are reduced. The only issue of course is how a non-uniform structure adds to cost. But I would go that way if I were in your shoes.

The other piece of maths you need to do is about where you want your speakers to be. This will require some research about where others have positioned your chosen speakers, to get a rough guide - mainly to figure out how far from room boundaries you will have to have the speakers before they open up. But what I am getting at is that the distances from woofer to room boundaries are best to be in a golden ratio too. Again, non-parallel surfaces reduces the risk of encountering problems.

To those of you still watching this thread; I have been researching more and getting closer to starting my project. I have decided on the basic materials needed for sound isolation properties; layers of 1)sheetrock/2)soundboard/and 3)sheetrock attached to the studs with resilient channel on ceilings and walls. I might use 2 X 6 plates with offset 2X4 studs so that the front and back of the wall aren't able to transmit any vibration through the studs. Floor: sheetrock/soundboard/ particle board and carpet. I would like to float the floor joists using a foam "U" device but don't think I can because these floors need to be attached to the first floor and I can't afford to do a separate floating floor joist method, unless I cut out the depth of the "U" foam, but then I'd still have to nail through it into the floor.
The room dimension issue is still a bit fuzzy. In order to meet the golden ratio requirement exactly for an 8' height, I need the room to be 15 X 11.2. The 11.2 seems a bit narrow and I'm wondering if I can stick to an even 12' without a noticeable audible increase in "resonant mode distortion". In other words, how precise to you have to be? How much variance from the golden ratio before you get a noticeable difference? I could even go longer without a noticeable increase in cost, but increasing the height gets pricey.
Joeb

Joeb,
You might consider opening the ceiling to the roof (cathedral). I have a second floor listening room over the garage that is 18'W x 28'D with 9' walls and a 13' peak. It is very close to the golden ratio. The extra height really opens up the sound stage vertically. I used the Cardas formulas for speaker placement from the side walls, but kept the speakers at 5' from the rear wall. The image is phenominally wide, deep and high and forward of the speakers. This room is one of the best I have heard.

Zargon, Great Idea. I have already thrown out the previous dimensions, way too small, I am going with a L22 by W15. the only question is to go with a 8' or 10' ceiling. Probably the 10'. The previous question remains to be answered however, re: the frequency resonant mode dispersion. with a 10x15x21 there is a pretty good balance across the fr. span from say 25hz to 300 hz, but some bundling in the low mid and hi mid range. I still don't understand how much variance of frq. dispersion transalates to sound distortion. Does say a gap of 25hz next to a mode make a "BIG" difference? Or does it require a 40hz span? etc. If anyone was really interested I could post the exact figures.
thanks, Joeb

Golden ratio is :
Phi = 1.618033..
Phi*Phi = 2.618033..

That will give you with 8ft ceiling approximately

8'x13'x21'

However the I would go with higher ceilings if possible