Wonderful tool you have built! I am on a Mac (Safari) it is very nice to use. Some questions, on the Bonello graph, neither x or y axis title or scale info show up?
I am in Colorado, so there is an altitude effect on how fast sound travels. You are taking into account temperature (I think from reading your earlier posts), what about adding a elevation option as well!
What about ceiling insulation treatment for 1st reflections affecting the Sabin calculations?
Sounds like it should be an option for you to enter the speed of sound. There's also humidity that affects the speed.
What did you have in mind? (words and algebra)
My first instinct is that First Reflections (either ceiling or walls) become a bit tricky to estimate for widly spaced stereo, even more widely spaced 5.1 front 3 speakers, and optimized/quantized for 2'x4' sizes that rigid material seems to come in.
I'm thinking about an 'explanations and references' link, but work is keeping me busy.
(sabins - front wall - carpet - ceiling (%covered x area) ) / Left+Right+Rear wall:
The line with the 'carpet' was for home theater owners, who tend to cover their floors with carpet no matter what.
If you want to cover the ceiling with stuff, then you can use the existing carpet line, since most rooms ceiling has the same ft^2 as the floor.
I was wondering if you gave any thought to making your room mode calculator into a stand alone program so that we could use it when not connected to the web? There are many times I am at a clients house and take a quick room measurement of a potential room, but have to wait until I get home to see the results of those dimensions.
It would be great if I could do it right there on the spot to let the clients know how their room fares from the start.
Dennis Erskine wrote:With respect to general issue of room size:
If one can build the room avoiding coincident modes, then that is the better choice; however, larger is better than smaller. If when examining the constraints, changing the dimensions makes the room impractical (too narrow, too low a ceiling, too short), then build the room anyway. It is doubtful, or at least questionable, that changing a dimension less than a foot is going to make a real world difference in any case. The actual as built physical characteristics of the walls, the addition of design elements, platforms, seating, and stages are going to throw their two cents into the mix and result in something different than the modal spreadsheet suggests in any case. If, when designing the room, you know in advance that you have a potential coincident modal issue, then within the design you can accommodate, or plan for the use of, any one of several mechanisms to deal with the modal problem. I would suggest an 11' wide room with no coincident modes, is less attractive than either no room, or a 13' wide room (with coincident modes) when all other needs are addressed.
Room modes just are. It would be nice to have all the modes equally excited, not audible, perfectly distributed, blah, blah. Sorry, that's not going to happen. You'll have modes, period. Rather you have one, five or ten, the solution set available is still the same. Move the seats, move the speakers, absorb, equalize, or turn off the amp. As I've noted several times, the spreadsheet calculators are interesting but (a) don't tell you all the information you need to know; and, (b) cause alot of arm waving and draw time and attention away from equally (if not more so) problematic (and solvable) acoustic issues during the design. Build the room. Build with some flexibility, measure the room and then fix the problem(s) you really have. Ok, so you're left with a triple coincident mode. So either fix it or have someone fix it for you. That's a far better choice than (a) no room at all; or, (b) wasting a month fretting about it at the expense of forgetting about the long list of other issues.
Layout your room to meet *your* needs of space, seating, picture size, budget, and the like and then move ahead.
RT60 (IEC/AEC N 12-A standard): 350 ms
- ±50ms from 200Hz to 3.5kHz = 300 to 400ms
- ±100ms above 3.5kHz = 250 to 450ms
- <+300ms at 63hz = 650ms
RT60 (ITU/EBU Control Room Recommended): 289 ms
- ±50ms from 200Hz to 4kHz = 239 to 339ms
- <+300ms at 63hz = 589ms
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