John - Material for wall units

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larrye

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John,
I am getting ready to buy the material to build your wall units and to treat my low ceiling. I am afraid you have already answered some of these, but I couldn't get the search to work yet.

Questions:

1. OK to wrap the Knauf fiberglass in black plastic to control the
dust from them, and then to wrap in about any cloth?

2. If 1" MDF is not readily availabe for the frame of the wall units
is 3/4" OK?

3. Does the kind of material used for the slats matter?

4. Slat size of 1x3 and 1x4 critical? Here in U.S. the nominal size
of a 1x4 is actually 3/4" x 31/2".

5. Are 3/12" thick fiberglass batt insulation OK for the Side Wall
Absorber?

6. Is it OK to paint the slat resonator?

Many Thanks,
Larry
 
1) yes its Ok to use plastic to keep out the dust.
2)3/4" is OK - I deal in metric allth etime usually and it's 20mm which is a metric version of 3/4" :)
3) No - Hardwood is better than softwood ideally but it really doesn't matter.
4) same as 2. Your 2 x 1 is what we call DAR (Dressed all round) in other words it's been planed down.
5) 3/12"????? that's 1/4"??
6) yes you can paint stain etc.

BYW Larrye - in your room I wouldn't put slats totally down the walls. I would add some panel absorbers for the low end. You could have the units divided with slats on the top section and a panel absorber on the bottom.

To make these replace the slats with sheets of 1/4", 1/8" plywood.

See http://www.saecollege.de/reference_material/pages/Low Frequencies.htm#panel

cheers
John
 
Thanks John,
I was trying to type 31/2" (backslash wrong place). Anyway
3-1/2 thick by 24" wide R-11 fiberglass batt insulation, was what I was trying to type. I hope it is ok?

Also, when I replace the slats on the bottom half of the defusers, do you seal the plywood all the way around to make a seperate box? And I assume you mean to alternate the panels between 1/8" and 1/4"?

Thanks for all your help,
larry
 
Last edited:
LOL - 3 1/2" will be fine.

Yes you make a separate box and seal all the way around. Try to vary the thicknesses of the ply as much as possible. - you can use hardboard as an alternative.

cheers
JOhn
 
larrye...will you please post some pics when you get them done. I am very interested in seeing what they look like.

Beezoboy
 
John,
Thanks again!

Beezoboy,

I will post pics when finished. I'm a little short of cash right now and it will take a while to build them so it might be a couple of months before I get them finished. I hope I can build them right!

Larry
 
oops..

I wrapped my 2" knauf boards with a colored burlap (not quite as open weave as the nasty brown stuff). I never covered the boards with plastic. Am I going to die a horrible death?
 
No Yadi - when putting on the ceiling as Larrye will be doing it's a good idea else your gear will always be covered in dust :):)

cheers
JOhn
 
What do you ask for?

When you chaps are buying the KNauf fibreglass board, what do you ask for? What is it actually called? I want to get some in England following John's rcommendations for my studio but want to make sure I get the right stuff before I order it in. What kind of price do you pay? Thanks for any help.
 
I called Knauff (found them on the internet) and they gave me a few suppliers. Funny thing is that they actually gave me a name of their customer who makes pieces for GM cars. I called them since they are so close by, and luckily, hit it off with some guy who pulled a few strings for me. I paid $5 per 2 x 4 panel which they cut for me, each one is 2" MDF (medium density fiberboard...I think is what that means). The "guy" knew exactly what I was doing and told me that what I was getting was actually getting a "more dense" knauf product then what I was looking for...good for lower frequencies. They work very well, worth the effort.

Thanks John: good to know I won't be on a respirator too soon...
 
Now I'm REALLY confused!

Sorry, Yadi, are you saying that you're using MDF instead of fibreglass? MDF is like pretend wood (well, woodshavings and glue mashed and pressed). Or are you saying you put the Knauf fibreglass in mdf frames? Sorry, I'm being a bit dense here probably! And what's the Knauf stuff's actual brand name?
 
Dr. X,

I may have my terminology screwed up, but what I'm referring to is "fiberglass board" from Knauf. Look at this link (below). What I got was the 2" version (plain, no paper covering) rated at 3.0 PCF (I believe that is pounds per cubic foot - density). Also, I believe, the higher the number the better for my application: diffusing some flutter and killing off some low frequency.


Knauffiberglass.com
 
Thanks!

OK Yadi, that makes sense to me now! Thanks for the link. That's brilliant, I can just go to my local builder depot and point at the page! Yes, MDF is the dense wooden-type board that cheap furniture and speakers are made of! You could use that to build a box to put your rigid fibreglass in. Anyway, that's great...I've now got a picture of the stuff!
 
And to John S...

Is this stuff in Yadi's link the same basically as the black Corning stuff?
 
Is this stuff in Yadi's link the same basically as the black Corning stuff?
Click to expand...

I don't know - I went to dowcorning.com but couldn't find any reference to insulation or fibreglass on their new flash slow site :mad: :mad:

cheers
John
 
That look like it Dr X. (Owens Corning!! more like it :):)

cheers
John
 
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