Roomtune spreadsheet download | John Sayers’ Recording Studio Design Forum archive

Roomtune is now available here, for those who requested it - no need to unzip, since this board accepts .xls files. Here are basic docs, you can cut/paste them wherever you need - Instructions and Suggestions for use of Roomtune Spreadsheet The function of this spreadsheet is to quickly see what dimensions work best for un-colored sound in a rectangular room. The formula is based on f=1130/2, assuming 1130 feet/sec for the speed of sound, and one round trip of each dimension of the room for the primary resonant frequency. There is no provision for any Tangential or Oblique mode calculations - There are other, more involved spreadsheets available that cover those and more. Roomtune is more of a “Quick Check” kind of tool. First, I make no claim to being a "Guru" on spreadsheets - Almost anyone who spends more than a couple of hours with a spreadsheet can improve on this one. The point is, if anyone else has done this I couldn't find it 18 years ago, so decided to "roll my own." I wanted to include an option for those who have no "office suite" on their computer and are saving what money they do have for audio goodies, but the only one I found is a shareware for $20; until you pay your $20, it won't let you import anything. After payment (online if you want) it will import Excel format and several others. Here is the URL for anyone interested (read "broke") It's called "GS-Calc 6". http://download.cnet.com/downloads/0-10 ... 15.7493071 Excel users - Just double-clicking roomtune.xls should get you everything. Screen resolution The sheet was formatted for 1024 x 768 . Any less and you won't see all the chart. Operation Simplest part. There are only 3 cells to enter data into - They are labeled L, W, and H for Length, Width, and Height respectively. Data can be entered in whole feet or feet and tenths. Warning: I have not "locked" any of the cells, so if you inadvertantly enter a number into one of the "formula" cells, hopefully you kept the .zip file and can start over. Just stay under the Bold Italicized L,W,H and you'll do fine. All of the rest of the fields in this spreadsheet are either labels, calculated, or chart. The label L-3, for example, refers to the third harmonic of the axial mode caused by L (length) This sheet works ONLY with rectangular rooms - if yours is splayed, call John Storyk or Alton Everest (if he's still taking calls - last I heard, he was 91 years old and living somewhere in California.) If you have a vaulted ceiling, you can at least see if the other two pairs of walls should work together, and you may be able to interpolate the ceiling from min and max heights - good luck on that one. Update - I’ve since learned that you can (sort of) get away with averaging dimensions in a non-parallel room, and it will at least give you an idea of what to expect. New Construction I'm not going to get into construction techniques here, that’s what the forums are for - you’re already here, drop in and say “hey”… Back to the plan... The way I use this sheet for deciding dimensions on new construction (Say, for example, that I am planning 2 rooms and 2 iso-booths inside an existing 36 x 48 barn) - this may seem large until you subtract enough space between outer and inner walls for the inner room construction - What I do first is find out how much headroom I have available - If doing completely new construction, you can work backwards from the inside dimensions you want, otherwise you need to subtract the necessary floated floor height and the thickness of the planned ceiling, plus space for ceiling hangers (with isolators) - After I find out what the maximum finished inside height can be, this is the first # I enter into the spreadsheet. Then, I figure out what the maximum width or length can be (inside dim's) and enter that # into the L or W cell. If you set two of the three dimensions the same, you can see the effect of changes on the third dimension easier, as they relate to the dimension you're trying to complement. You can also enter "0" into one of the cells so you only see the effects of two of the dimensions. Once you have a (seemingly) workable pair of dimensions, it's time to go for the third. (If you're at a loss, try 10 x 16 x 23.3, or same ratio's with 8' ceiling would be 8 x 12.8 x 18.6. ) The smaller the room dimensions, the harder it will be to elude coincidences and big gaps. (See below) The third dimension quest will cause you to re-examine the second easiest-to-vary dimension, until you get a bar-graph that shows evenly distributed resonances within the room. One thing that helps make this a little easier, is that I've set the cursor option to "stay where it is" when using the "enter" key. This way, if you're only trying to compare different values of ONE of the 3 dimensions, you just keep typing whole numbers of feet into the cell and hitting "enter" - then, when you get close to what you want, go to feet and tenths of feet, til you get as smooth a response chart as possible. Assuming a reverb time (dependent on absorption and dimensions) of about 0.5 seconds, each harmonic of each axial mode should be about 4hZ wide at the 3dB point. The goal is setting room dimensions so that there are no coincident harmonics, (at least 5-6 hZ apart) no harmonics further apart than about 25 hZ, and as even a spread between adjacent harmonic frequencies as possible. If you can accomplish this given whatever restraints you are stuck with, you win. As you play with this spreadsheet, you'll see how difficult it can be to achieve this. Even one of the so-called "perfect" room ratios of 1:1.6:2.33 doesn't look quite perfect on this graph. If you have lots of headroom and less floor space, (say for an iso-booth) consider "standing the room on end" - The response, other than for early reflections, doesn't care whether a room is 10 feet long and 23.3 feet tall, or the other way around. Existing construction - (sorry, renters, life's a bitch) I've used this method in a room I built ages ago, when I still thought "soundproof" was spelled "egg carton" ( in other words, shoulda' read more and built less) If your room sucks according to both experience and plugging it into this spreadsheet, try setting first the length (only) to zero, then the width (only), to see if two of the dimensions are usable. (ceiling too, if it's tall enough in the first place to allow "dropping") If you find that two of the dimensions work together, then place the cursor over the one that doesn't work. Then, starting with the longest possible dimension you could use, type in shorter and shorter dimensions until you can find one that evens out the response. When you get close, go to feet and tenths to "dial it in". Remember to watch harmonics further up the scale - an "L-1" that looks perfect at "L-2" and "L-3", may suddenly coincide perfectly with a "L-4" vs."W-3" harmonic. Sometimes one or two tenths of a foot will fix one coincidence without screwing up the lower ones. Also, sometimes a big "gap" in lower harmonics will be filled in by one several columns over. The order of the frequencies isn't as important as the gap; plus, those Tangential and Oblique modes help fill in gaps in response - so, too much obsessing over a bigger gap in response is kinda pointless... Once you find a new dimension that works, consider building a wall there, and maybe using the other space as either instrument storage, repair shop, bass trap, etc. Depending on its size. This should get you on your way to being more "anal" than you ever wanted to be - If not, you'll have to find your very own way to be wierd... If you don't want the sheet to open on your computer (assuming you have Excel installed) then you should Right Click on the Download link and use the "Save As" option - P.S. - I welcome all reasonably polite comments, please post on the construction forum… Steve

File not preserved: roomtune.xls