2. tech-talk
  3. 1039324177

the listening room: "golden ratio"?

I too am about to build a listening room, actually, I'm building a garage and adding the room over the top. There seems to be a lot of advice to pay attention to the "golden ratio" which, essentially requires a room at least 25 feet long, by, roughly 17. this seems really "BIG". The rationale for the size is based on the theory that the lower hz frequency has a "wave length" of 25' or something to that affect. However, there are few speakers that reach down to that range. I have BW N804, whose freq. response is around 40hz. I was thinking of getting some N803's which add a bit, but still nothing close to 20hz. As nice as it might be to build a 25'X 17' room, I'd like to stick to somehthing around 15 X 12, roughly half the total size of the garage. How much would I "lose" in that size? The other consideration is the cost of heating this room, living in the north, my electronics would not like to spend the winter out there at -30 and electric base board heat would run up a hell of a bill.
thoughts?
joeb
joeb

Showing 4 responses by joeb

joeb OP
121 posts
 
Nar, com, Now I'm really confused, I thought the ratio was:
1: 1.4: 1.9 where 1= height etc. And why, if 8x13x21 is the "gr" would you go with a higher ceiling?
joe
joeb OP
121 posts
 
Red,
Yes, I found the same info on resonant modes/room dimensions in Robert Harley's "High End Audio" suggested here by others. Hence, this fits into my budget nicely. The exact dimensions for an 8' ceiling is: L 15.2' X W 11.2' X H 8'.
That at least minimizes bass "boom" and other resonant modes. frequency modes. Other than that, I need good accoustical construction, which was mentioned but not really explored well in that book. I will have to purchase another book mentioned here; Alton Everst's book.
Thanks for your help
joeb
joeb OP
121 posts
 
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 OP
121 posts
 
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
More to discover