Nodes and Slatted Thingys

frederic · Post by **frederic** » Wed Nov 26, 2003 3:59 am

Steve,

What do you use to calculate room nodes, and determine the location and the thickness of the slats and gaps in such devices?

While I'm nowhere near ready to make such things as I'm still doing the initial construction, I'm thinking its time to start looking more seriously at what I may end up with as far as nodes, wall to wall flutter, and start gathering the materials to make appropriate sound absorbtion devices.

And can this software/spreadsheet do complex rooms? I have a slanted ceiling as you know, as well as a 32" wide slant on the right side of the room opposite the console table as well, a sofa nook, etc.

Just curious what you use, and the process involved.

knightfly · Post by **knightfly** » Wed Nov 26, 2003 5:16 am

You already OWN the only software I know of that's both affordable by HUMANS and that will do complex rooms - all the other stuff is just variations on the theme - all of those are Excel sheets, most of which just do Axial modes (the strongest and most influential)

There's one I wrote upteen years ago, here

http://johnlsayers.com/phpBB2/viewtopic.php?t=643

One from Harmon's site (better visualization of where problem areas might show up -

http://www.harman.com/wp/index.jsp?articleId=131

And this one (click on Calculation tools, it's the top one, ModesV2)

http://www.studiotips.com

That last one does all three types of modes, a Bonello distribution plot, and has some useful text info on the first page as well.

NONE of these will do anything but a rectangular room - without spending the weeks it takes to get CARA to actually work, the only thing you can do is use average dimensions and guess a lot.

You might be better off to just build it, then use either CARA with the "Audio controller" - finally got an answer to my email question there, they've tested the RS-232 controller with several USB adapters and no problem) or use ETF (my next software addition) and fix the problems that actually show up acoustically.

There's another Excel sheet at John's old site that does slat absorbers, you can either use it there or download the Excel file -

http://www.saecollege.de/reference_material/index.html

to download the Excel file for local use offline - right click on the Helmholz Calculator link in the sidebar, then click "Save As" -

In practice, I use mine and Studiotips' the most, with Harmon's a close third. I've only lacked about 2 weeks of 12-hour days of having time enough to dig into CARA far enough to be useful, gotta find out if using their "controller" is as time consuming. If so, ETF gets the next Paypal bump... Steve

frederic · Post by **frederic** » Thu Nov 27, 2003 10:55 am

Thank you Steve, you're kind and a gentleman.

I will start slurping all that down and see what I end up with. Since I have a lot of strange angles, coves, and other interesting room things I'm sure actual will vary from spreadsheet, but its a good exercise to point me in the right direction.

Thanks again!

knightfly · Post by **knightfly** » Thu Nov 27, 2003 11:23 am

You're entirely welcome - just a "SWAG" here, but I'd be surprised if you had any flutter problems with your strange combination of angles -

Meantime, be sure and have a happy/safe Turkey day - I get to work 12-hour days both Thursday and Friday, then 12-hour nights Sat and Sun - Whole family's gonna do a late dinner Thursday so I won't have to make a fool of myself in private - then, after TG dinner I'll just take a PROPER nap, wake up at 04:25 and get ready for the "DDJ" again - it's cool tho - with Wifey in nursing school instead of working, the extra holiday pay keeps me from having to dip into "toy money"... Steve

frederic · Post by **frederic** » Thu Nov 27, 2003 12:58 pm

You're entirely welcome - just a "SWAG" here, but I'd be surprised if you had any flutter problems with your strange combination of angles -

One can certainly hope. I would be very pleased if the room works 80% without any treatments, then fix the last bit with foam, slats, and the like.

Meantime, be sure and have a happy/safe Turkey day - I get to

You too, you and yours enjoy despite your work schedule. I'm happy to have off tomorrow, though we have early company so I'm not that sure I can cover myself with spackle for too long. Then, we're all going to friends about a mile from here for T-day dinner, then friday I'm "working from home".

with Wifey in nursing school instead of working, the extra holiday pay keeps me from having to dip into "toy money"... Steve

Understood... My wife has been looking for IT work for a year and a half now... and if it weren't for selling automotive junk on skank-bay I'd have no "toy money" at all.

Be well man!