Small room modes : some questions !

Hello :) I'm currently doing some research and self teaching about acoustic, difficult but nothing is impossible ;) I'm reading the famous master handbook of acoustics, and I've some question about the modes ! I have a nice place to play and record, unfortunately, it's an acoustic disaster (for the moment ;) ). You can see the main thread here : viewtopic.php?f=1&t=15053 So, the main problem is that I've beam of concrete, at 2,19m high ... that's means low ! If I look at the Louden ratio (1/1,4/1,9), I think I can almost goes right with these dimensions : 2m/2,80m/3,80m. It's just about the dimensions of my room (see the linked thread for more informations). A look at the results in bob golds mode calculator give me good results, as far as I understand : no big mode, modes pretty evenly spaced. So it's allright, isn't it ? Two questions so : 1. Are the results valid for such a small volume ? it's only 21,28m3 ! 2. I'm planning to do the typical framing isolation, to get rid of some interfering noises. When we talk about a room ratio, and room size, do we talk about the inside wall (the framing+drywall), or the outside, thick walls ? As I can understand, both will cause nodes, am I right ? It can make the task pretty hard, as my base room (with very thick concrete walls) is asymetrical, and complicated : Any help will be appreciated, and any opinion on the other thread too ;) Best regards -fx

Fx, As a rule, I recommend a minimum of 42 cubic meters for a critical listening/mix space. 1. The calculations are valid for any dimension but they assume a perfectly reflective enclosure. I do not hold 'stock' in any so-called ideal ratio. These ratios are starting points. Many times, given real world situations/dimensions, the ratios can produce a bad acoustical environment. Never go by ratio alone. Use a good mode calculator and be sure that you understand it. :wink: 2. These must be the internal dimensions to the hard shell internal wall surface. Cheers, John

Hello John ! Thanks for the precious informations ! -fx PS : I you take a look in this subsection of the forum, you'll see that I ended with a totally different design !