What acoustic treatments for vocal booth?

Posted: Wed Dec 25, 2002 1:59 pm

I would opt for a dampened approach.

Posted: Wed Dec 25, 2002 9:48 pm

That'd work - I'd expect some really squeaky clean recordings using that approach...

Posted: Thu Dec 26, 2002 11:59 am

Ok Steve,I've just found time to resume all your explanations from your last post and before...

Now i'm getting things than i hadn't got yet(yeah, think i'm in the next step);BUT, here's my own "translation", it may reveal if i'm ok or not ,being in the same time a new summary!

-FIRST STEP: THE FRAME
- Two 2"x4"(originally) studs,horizontally mounted,one at the bottom,the other at the ceiling,both with angles cut at the connection with the 2 walls(2 connections:at 6"/at 12" from the original wall) and with caulk to prevent air from passing trough;
-Four 2"x4" studs(1 at the left wall,1 at the opposite wall,and the 2 last ones between),all vertically mounted BETWEEN the horizontal studs described above,square with them at their connections and caulked as usual;the 2 middle ones being mounted with insulation board as a guide for optimal positions.
===SO,these four studs should not be 5,19 long,BUT 5,19 less 2 times the horizontal studs width(since they are placed BETWEEN them),say 5,19-2x2" !...?

-SECOND STEP: THE INSULATION BOARDS
-Since the insulation boards should be placed BETWEEN the vertical studs,in order to fix them,we need to add 1"x1"cleats vertically mounted BEHIND the vertical studs showing a 1/2" width part of these cleats at the inner(left/right) side of the studs.So the insulation boards will be "stopped" there,fixed with glue and nails...Now we've got sort of "frames within the frame",putting THEORICALLY the outside edge of the insulation boards at 12" to 6" far from the original wall.
====I say THEORICALLY because if the (vertical) studs are in fact less than 2" deep,i mean 1,5",HOW can the insulation boards not go beyond the studs line?

THIRD STEP:THE SLATS/SLOTS
-Now we should fix the slats DIRECTLY ON the studs for better maintained position than it would be if just mounted on the insulation boards;The slats/slots width/depth depending on the matching cavity depth behind the insulation boards,boards which should be CLOSE to the slats for better absorption...
====BUT:The side of the frame that is toward the open area of the booth,WAS the "line"(going from 6" to 12" far from the original wall) used for modal calculations.So if you consider that " the outer surface of the SLATS determines the surface to be used for modal calculations",we'll have LESS depth than the average 9",but 9" + 1,5"(slats width) !....?

Again,sorry to repeat myself about the results from the room modes calculated for 5,2' and 5,7',i was speaking about the center of group of nodes FOR the 5,7' dimension,NOT for the 5,2 dimension.
=====For 5,2' dimensions H2,L2,W2=157,178,217/CENTER=187HZ====OK
=====For 5,7' dimensions H2,L2,W2=157,178,198/CENTER=177,5HZ but not 187HZ ??

Steve,i hope i'm not so far from the final thing !

Thanks again,

Greg

Posted: Thu Dec 26, 2002 12:04 pm

Sorry ,correction to my post:
"we'll have LESS depth than the average 9",but 9" + 1,5"(slats width) !....?">>>>>Correction:"We'll have MORE depth"( and less dimension in the room)

Posted: Thu Dec 26, 2002 5:25 pm

Greg, I think we're almost there - your questions, sort of in order:

"SO,these four studs should not be 5,19 long,BUT 5,19 less 2 times the horizontal studs width(since they are placed BETWEEN them),say 5,19-2x2" !...?"

Yes, except they would be 7.19 feet minus the thickness of the two bottom and top horizontals, not 5.19 feet.

"I say THEORICALLY because if the (vertical) studs are in fact less than 2" deep,i mean 1,5",HOW can the insulation boards not go beyond the studs line?"

I think you have just one slight misunderstanding, my fault for not explaining more clearly - the vertical studs, which are 1.5" x 3.5", get placed between the two horizontals, with the LONGER (3.5") dimension turned so that from the front of the trap, you would see the NARROW edge of the stud. This way, there is a 3.5" depth, with plenty of room to place the cleat at the back edge and still have room for the insulation board in front of the cleats. When the frame is complete except for the slats and insulation board, all the pieces of the frame will have the same depth front-to-back, or in this case 3.5 inches.

"we'll have LESS depth than the average 9",but 9" + 1,5"(slats width) !....?">>>>>Correction:"We'll have MORE depth"( and less dimension in the room) "

Correct, but this is insignificant when viewed as a ratio of the overall dimension of the room versus 1.5" - that amount of change for the 5.2 foot dimension results in a frequency shift of less than 2 hZ, and ONLY for the width harmonics. The trap is tuned broader than that by means of the variable depth, so you would never hear the difference. Rupert Neve, in his wildest wet dreams, wouldn't hear it, for that matter. In fact, you could round the depth of the trap from 12"/6" (305mm/153mm) to 300mm/150mm if your measuring tools are graduated in mm, and the numbers don't change at all in the spreadsheet. That particular dimension isn't NEARLY as critical as the slot width. (Distance BETWEEN the slats)

"=====For 5,2' dimensions H2,L2,W2=157,178,217/CENTER=187HZ====OK
=====For 5,7' dimensions H2,L2,W2=157,178,198/CENTER=177,5HZ but not 187HZ ??"

Correct. for the 5.7' dimension, the AVERAGE and the L2 mode come within 0.25 hZ of each other. The shorter, 5.2' dimension at 217 hZ for W2, raises the AVERAGE of the second group of modes to 187 hZ.

Did you find out yet what dimensions your local suppliers carry in lumber? If they're different, we'll have to re-calculate a few things. At least, you sound like you're getting a good understanding of the basic design ideas, so re-calculation would only change some dimensions, not the actual design... Steve

Posted: Sat Dec 28, 2002 6:53 pm

Nightmusic
Frame of a US style house is shown on the page I have linked below. The basics of houses are the same but their are regional variations due to climate and custom differences in different regions. Down south where I am basements are unheard of in the norther colder areas they are under almost every home.
Frame of Home

I sure hope this clears up your picture of US wall in case you are still having difficulty.

Posted: Fri Jan 03, 2003 5:56 am

Hello guys,

Few days have past since my last post,was just in a big working week...
First let me wish all of you a happy new year 2003,with special congratulations to RO which is just one of the best musical site on the Net,truely!Thanks to those people who give their time and knowledge to RO users like me,they are also the reason of the RO success...

So...let's go back to the subject...
Thank u jeeper for your link it was interesting to know how house are built in US when they're made of wood...You know in France that's rare to see that kind of constructions,most of houses are made with plasterboards,or they're brick-built /stone-built ,lumbers are used only for roof construction.Curiously,we can also find wood constructions for chalets,at the mountains,you know where it's cold!

So... today i think most of things are clear in my mind about that broadband absorber construction...

" the vertical studs, which are 1.5" x 3.5", get placed between the two horizontals, with the LONGER (3.5") dimension turned so that from the front of the trap, you would see the NARROW edge of the stud."
Thanks for that precision Steve,now i think i figure out the right thing.So that's the right moment to give you the dimensions lumber that i can find here in Paris:

In millimeter,to avoid translations mistakes:
1)60X80 mm
2)60X40 mm
3)63X75 mm
-------------------->Where us lumbers are in mm:38X89 mm...So i don't know which choice is the better in my case.
One more thing:I still have to go and see them because i just had the information on the net from the main store here in Paris which provides these lumbers .Pictures from the net can sometimes be far from reality.Anyway they don't seem to be radiused,so the dimensions should be the actual ones.But i still have to check if the fir they are made of is strong enough to ensure good solidity,well cut,not curved,etc...
Thanks again,Steve,see you

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