Room volume V Room ratio

In my space Im looking at constructing a space of 11.9W x 19.1L x 8.5H. This gives the following results in Bob Golds nifty calculator Computed Information: Room Dimensions: Length=19.07 ft, Width=11.9 ft, Height=8.5 ft Room Ratio: 1 : 1.4 : 2.24 R. Walker BBC 1996: - 1.1w / h < l / h < ((4.5w / h) - 4): Pass - l < 3h & w < 3h: Pass - no integer multiple within 5%: Pass Nearest Known Ratio: - "8) M. M. Louden: 1971: 4th best ratio" 1 : 1.5 : 2.2 RT60 (IEC/AEC N 12-A standard): 247 ms - ±50ms from 200Hz to 3.5kHz = 197 to 297ms - ±100ms above 3.5kHz = 147 to 347ms - <+300ms at 63hz = 547ms - 300<RT60<600ms RT60 (ITU/EBU Control Room Recommended): 204 ms - ±50ms from 200Hz to 4kHz = 154 to 254ms - <+300ms at 63hz = 504ms - 200<RT60<400ms Absorbtion to achieve ITU RT60: 462 sabins Volume: 1929 ft^3 Surface Area Total: 980 ft^2 Surface Area Floor: 227 ft^2 Surface Area Ceiling+Floor: 454 ft^2 Surface Area Front Wall: 101 ft^2 Surface Area Front and Rear Wall: 202 ft^2 Surface Area Left Wall: 162 ft^2 Surface Area Left and Right Wall: 324 ft^2 Surface Area 4 Walls: 526 ft^2 Surface Area 4 Walls + floor: 753 ft^2 (sabins - front wall - carpet) / Left+Right+Rear wall: 31 % (sabins - front wall) / Left+Right+Rear wall: 84 % Schroeder Fc: 115hz Frequency Regions: - No modal boost: 1hz to 29hz - Room Modes dominate: 29hz to 115hz - Diffraction and Diffusion dominate: 115hz to 460hz - Specular reflections and ray accoustics prevail: 460hz to 20000hz Count (29.6-205hz) : Axials=13, Tangentials=54, Obliques=72 Count (29.6-100hz) : Axials=6, Tangentials=6, Obliques=1 Critical Distance (direct = reverberant field): 13.60ft The length can be varied in my room. So I could nail a much better looking ratio of Loudens best of 1:1.4:1.9 , 11.9W x 16.1 x 8.5H which gives the following: Computed Information: Room Dimensions: Length=16.07 ft, Width=11.9 ft, Height=8.5 ft Room Ratio: 1 : 1.4 : 1.89 R. Walker BBC 1996: - 1.1w / h < l / h < ((4.5w / h) - 4): Pass - l < 3h & w < 3h: Pass - no integer multiple within 5%: Pass Nearest Known Ratio: - "5) M. M. Louden: 1971: Best ratio as per Louden" 1 : 1.4 : 1.9 RT60 (IEC/AEC N 12-A standard): 233 ms - ±50ms from 200Hz to 3.5kHz = 183 to 283ms - ±100ms above 3.5kHz = 133 to 333ms - <+300ms at 63hz = 533ms - 300<RT60<600ms RT60 (ITU/EBU Control Room Recommended): 193 ms - ±50ms from 200Hz to 4kHz = 143 to 243ms - <+300ms at 63hz = 493ms - 200<RT60<400ms Absorbtion to achieve ITU RT60: 412 sabins Volume: 1626 ft^3 Surface Area Total: 856 ft^2 Surface Area Floor: 191 ft^2 Surface Area Ceiling+Floor: 382 ft^2 Surface Area Front Wall: 101 ft^2 Surface Area Front and Rear Wall: 202 ft^2 Surface Area Left Wall: 136 ft^2 Surface Area Left and Right Wall: 272 ft^2 Surface Area 4 Walls: 474 ft^2 Surface Area 4 Walls + floor: 665 ft^2 (sabins - front wall - carpet) / Left+Right+Rear wall: 32 % (sabins - front wall) / Left+Right+Rear wall: 83 % Schroeder Fc: 122hz Frequency Regions: - No modal boost: 1hz to 35hz - Room Modes dominate: 35hz to 122hz - Diffraction and Diffusion dominate: 122hz to 488hz - Specular reflections and ray accoustics prevail: 488hz to 20000hz Count (35.1-217hz) : Axials=13, Tangentials=54, Obliques=72 Count (35.1-100hz) : Axials=5, Tangentials=5, Obliques=1 Critical Distance (direct = reverberant field): 130ft Wow, so should I go the better ratio but less volume, or more volume and ignore the ugly Bonello curve and stacked modes? The Bonello curve particularly looks a thousand times better! However, I especially liked the extra volume option with the longer length. Especially as I could screen off the last foot or so of the wall for a thick trap and still have a somewhat spacious CR. But NEVER at the expense of the better sounding option, of which Im pretty confused. Thanks again as always.

I shoul add I plan on flush mounting the monitors. From what I can understand this may well make any calculations pretty much useless anyway?

I shoul add I plan on flush mounting the monitors. From what I can understand this may well make any calculations pretty much useless anyway?

Not necessarily! What makes modal calculations next to useless is rooms where the walls are grossly non-parallel. In MHoA, Everest says that you can average the dimensions for small angles and still get a reasonably valid result. Unfortunately, he doesn't say how much the non-parallel angles can be before the results are no longer valid, and he doesn't say what constitutes "valid" either, but you are probably reasonably OK with small splay angles. OK, so flush mounting implies large angles for the infinite baffles, but they only cover a part of the front wall, so there is still some validity for the results, especially for the vertical axial modes (which aren't affected at all) and for the lateral axial modes (which are less affected that the longitudinal modes). Tangentials that don't involve the front wall should also be reasonably close to reality, bu the other tangentials and all of the obliques will be off to a certain extent. In other words, just putting your speakers in angled infinite baffles does not necessarily invalidate using a modal behavior calculator to give you a rough idea of the probably modal response. Regarding your question on volume vs. ratio: If the Bonello looks lumpy, especially if you have more than one "hump" in it, then I'd try to do something about that. And if you have modes in the low end that are lining up perfectly, I'd DEFINITELY do something about that! The good thing is that even with your best ratio, your room volume is still pretty good, and exceeds the minimum ITU and EBU recommendations for critical listening rooms. So I reckon I'd go with that one. Having said that, you don't need to go crazy on ratios! Just get far away from the bad ones, close to one of the good ones, and that's fine. The room sill still need treating anyway, regardless of the ratio (there is no such thing as a "perfect ratio" or a "gold ratio"), so just aim to get close to a reasonably good one that also gives you good room volume, and you'll be fine. - Stuart -

Thanks again Stuart for the informative answer. I was kind of hoping you would say go the longest you possibly can and hang the ratio ! There is a vast difference in the bonello curves between the two length dimensions though,so I'm going to have to go with 16.1ft I think.

1 1:4 2:1 , Loudens 6th best looks ok. Not as good as his first but gives me a little extra in the length dimension. Would love to go 1:6 in the width, but the width ain't there :0).