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Discussion Starter #1
hardman has been kind enough to furnish us with a couple of nice downloadable progams that might come in handy all along. Thank you hardman!

The first program is a Room Dimensions Mode Calculator. This is a Microsoft Excel Worksheet that allows the user to enter their room dimensions and then see how close/far apart the modes are for their space (program works for 0 to 300 Hz). To use the worksheet you will have to enable macros. Just enter your room dimensions (red) and then click the clear button and last the plot button.

.xls file: Room Dimensions Mode Calculator (Excel 2003 only)

.xls file: Room Dimensions Mode Calculator (for older Excel versions)

Remember: you must enable macros when it loads the program.


The second program is a very complete converter tool. This is not your ordinary converter... it has 22 different conversion categories and converts about anything that could possibly be converted.

.zip file with .exe program: Converter


Here is a link to another room mode calculator that htnut12 provided...

Room Mode Calculator
 

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Hey Sonnie,
Quick question.
Is there a general rule of thumb for vaulted ceilings to be used with this calculator?
TIA
Jim
 

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Discussion Starter #3
Hmmm... I don't think I know how to calculate it, but surely someone does. Maybe hardman will know and chime in.
 
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Azjimmy raises a good question but unfortunately the formula I used to make the room mode calculator only works on a rectangle room with a flat ceiling. I am sure there is a formula that will address sloped walls, but I don’t know what it is or have access to this information.

Sorry - Chris
 
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yo, yo, yo. I beleive that you need to average the max/min. I could be wrong, but it is an approach that I read for non rectangular roomages.

Lates

T

:wave:
 
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The spreadsheet, good as it is, as supplied only calculates axial modes, which admittedly are the most powerful but tangential modes i.e. those that strike four surfaces as opposed to the two in axial modes, only lag around 3dB below but at very different frequencies due to the varying path lengths.

When I was teaching acoustics in a music college I used to impress on students that calculating modes was interesting in theory, but not much use in practical. There is no short cut to identifying "boom" frequencies but by lenghty actual measurement with a frequency generator/ or test tone CD and a sound level meter. When you have identified the one or sometimes two fundamentals which are causing problems and treated them by trapping you will be on the way to hearing your equipment/system as the manufacturer intended.

I also used to stress that the sound system is the equipment and the room.
 
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room modes in non-rectangular rooms can be tricky. We use a min, max and average analysis when designing spaces that have on set of surfaces that are not parallel. (sloped ceiling, angled side walls). Once you get more complicated than that, then you have to go into a complex simulation....When considering modal distribution we believe that all modes must be considered. The bonello criteria is based on Axial mode distribution but we look at Oblique and Tangential modes as well, as they do help "fill in" the areas above the fundamental for each dimension in small rooms. Hope this makes sense....:nerd:
 

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I snagged a room mode calculator off a link on the IB Cult which gives a nice graph like this. You can place two speakers and the seat in the room and it calculates the response at the seat. Really nice.

 

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All of these tools just accentuate how much I have to learn - they are all pretty much greek to me. Is there any online "crash course" out there that will allow me to at least make use of the basic functionality? Or would that be like asking for a crash course in graduate quantum mechanics for someone who is just starting to understand classical mechanics....?
 

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The link I posted gives you an Excel Spreadsheet that runs some Visual Basic Code automatically. First you input the dimensions of your room, length, width and height. You can input your listening position by calculating the position of your head away from the front, left wall and floor. Then you put in the location of your subwoofer, up to two subwoofers. Same way distance from front, left wall and floor. By moving the location of the sub or subs you can see the peaks and valleys that are due to the standing waves generated by reflections in the room. You can change the reflectivity of the surfaces too. So a hard smooth wall of drywall or plaster would be very reflective. A carpeted floor would be less so.
 

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Thanks, Jerry!
 

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When trying to use the room dimensions mode calculator in this thread (post #1), I can get it to come up ok (I have the macro security set to 'medium, so I can use macros fine), and I can enter my room dimentions with no problem. But when I hit the 'Plot' button, I get the following error:

Run Time Error '1004'
Application-defined or object-defined error
and hitting the 'Debug' button yields

Selection.Sort Key1:=Range("b31"), Order1:=xlAscending, Header:=xlGuess, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom, _
DataOption1:=xlSortNormal
At first, I thought I merely forgot to install VB with Excel, but that is not the case either. Does this mean anything to anybody? I am using Excel 2000 (I downloaded the calculator version "for all versions older than Excel 2003"), and WindowsXP Home. Thanx!
 

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Room calculations, tried some but when i input the height etc etc and it made a calculation, i see 2 rows and then copie them for txt file but its all weird. I included a txt file. Maybe a stupid question but can there be a page made for dummies like the BFD?
 

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Sonnie;2011.xls file: [URL="http://www.hometheatershack.com/roomcalculator.xls" said:
Room Dimensions Mode Calculator[/URL] (Excel 2003 only)

.xls file: Room Dimensions Mode Calculator (for older Excel versions)
Neither of those will generate a plot in Excel 2004 giving an error on this line

Selection.Sort Key1:=Range("b31"), Order1:=xlAscending, Header:=xlGuess, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom, _
DataOption1:=xlSortNormal
I did write a rectangular mode calculator in 360 assembler back in the mid 70s... maybe i'll have a look at fixing this ... (but excel is such a kludge...)

dave
 
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Sorry to hear some of you are having difficulties in getting the Excel doc to work correctly. Not sure what is causing the issues (works fine for me…), but Ethan has a similar program on his site that runs without needing Excel. I suggest you all try his application. www.realtraps.com/modecalc.htm

Also, please note this approach (my Excel doc) to room mode discovery is very basic at best. Its intended purpose was to help assist in determining the best room dimensions for new construction.
 

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I agree not to get too hung up on room modes. Many rooms designed from scratch won't be rectangular. Plus, the rooms we are talking about will usually have lots of absorption. Thirdly, For an existing room, or a room once it is built, the room needs to be fine-tuned anyway, so the modes must be verified by testing.

The theory is nice to have but it also assumes that the room boundaries are hard and rigid. At very low frequencies this is probably not true for non-masonry walls (ie plasterboard or sheetrock or whatever u guys call it stateside). So, again, that means testing.

When I am designing a room I make sure that the room dimensions are not integer multiples of each other, then I check the room mode calcs but I don't get obssessive and check 200 different combinations (ok maybe 10 or 20), and then I allow for tuned absorption treatment.
 
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