[Big Red Machine]

It has to do with density of the material.

That's what I learned from you years ago.  They were mentioning std OC pink as a better alternative to 703 in the super chunk form.  This didn't make sense to me.  I must not understand what super chunk is.

[jk@home]

Interesting. I have been reading several threads that say R-13 is adequate and may even be better for bass traps. This is based off of the "superchunk" design, not rigid panels spanning the corners. I welcome further discussion about these 2 materials.

If you can find R-30 of the same material, that would be thicker, less cut pieces required. Now that you have me researching fluffy insulation for superchunks  , it seems that if used, you don't want to stack it too high as is, due to the bottom pieces will compress from the weight above. So you have to come up with a way to support the layers every ? inches or so. Is this what you found? Here a gearslutz thread regarding this:

http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/750699-insulation-behind-straddled-corner-bass-traps.html

[bpape]

Doing fluffy behind 703 can help extend how low they will go. Doing full fluffy can have the effect of overabsorbing upper bass and lower mids with some materials. 

[jlafrenz]

That's what I learned from you years ago.  They were mentioning std OC pink as a better alternative to 703 in the super chunk form.  This didn't make sense to me.  I must not understand what super chunk is.

Superchunk is a bass trap that is triangular and fills the entire corner. Many make them by cutting acoustic material into the desired triangle size and stacking them to fill the corner.

[jlafrenz]

If you can find R-30 of the same material, that would be thicker, less cut pieces required. Now that you have me researching fluffy insulation for superchunks  , it seems that if used, you don't want to stack it too high as is, due to the bottom pieces will compress from the weight above. So you have to come up with a way to support the layers every ? inches or so. Is this what you found? Here a gearslutz thread regarding this:

http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/750699-insulation-behind-straddled-corner-bass-traps.html

Part of the issue I face in building these traps is the material that is readily available. It can be difficult to find some of the larger sizes at local hardware stores. Ordering it online increases the cost a decent amount due to shipping costs. R-30 may take less time to cut, but it seems harder to find in an unfaced in a 24" wide roll. This would make the face larger than the 24", but it seems necessary for the pink fluffy to work. The next issue I face is addressed below. While I am looking for the best bang for the buck solution, it doesn't make sense to skip and have something that is not effective or negative consequences.

I too have been looking over the designs about how to stack either material in the corner and support it. I have a few ideas in my head, but nothing I am ready to commit to yet. Once I do figure out something, I plan to create a full blown build thread with pictures and descriptions of the process.

Doing fluffy behind 703 can help extend how low they will go. Doing full fluffy can have the effect of overabsorbing upper bass and lower mids with some materials. 

This is what has me hesitant about going full fluffy in the corner even though it is less expensive. I feel that over absorption here would kill the life of the music for me.

[jk@home]

...I too have been looking over the designs about how to stack either material in the corner and support it. I have a few ideas in my head, but nothing I am ready to commit to yet. Once I do figure out something, I plan to create a full blown build thread with pictures and descriptions of the process...

Right off the top of my head, I would think you could use some of that (non-stretchy) landscape cloth, plastic netting, or similar thin material that will hold a long staple. Just cut out triangles, slightly larger (for staple edges) than the insulation triangles. Do a layer or two of insulation, than lay the landscape triangle on top of that and staple the back edges to the two side walls of the corner. Maybe then cover the entire stapled edges on the walls with some Tyvek tape (or something else just as sticky), for good measure. If you don't think the staples will stay in the walls, just put up some thin plywood first. Then repeat the steps. Finish the exposed front like one usually does to a superchunk (or cover it with a couple wrapped and stacked OC703 panels )

[Big Red Machine]

Superchunk is a bass trap that is triangular and fills the entire corner. Many make them by cutting acoustic material into the desired triangle size and stacking them to fill the corner.

As I mentioned, I did this with 703 in 24x18x18 triangles floor to ceiling.  At the time it was the superior methodology as I knew it.

[jlafrenz]

Interesting idea. I would think that a staple would hold in a wall if it only had a couple layers of material on it. That may become a lengthy process though. I have been thinking more along the lines of framing it out into 3 sections and using peg board as the shelf.

[Big Red Machine]

http://www.audiocircle.com/index.php?action=gallery;area=manage;album=3817

There is one photo in this old gallery of mine that shows how I framed the bass traps into the corner.  Since they were floor to ceiling, I made a frame out of 1x3's with beveled edges and then wedged it between floor and ceiling.  Maybe this will give you some more ideas.  I stapled stretchy fabric that i covered my absorbers with over the frame first.  The wedges just set on one another floor to ceiling.

[jlafrenz]

http://www.audiocircle.com/index.php?action=gallery;area=manage;album=3817

There is one photo in this old gallery of mine that shows how I framed the bass traps into the corner.  Since they were floor to ceiling, I made a frame out of 1x3's with beveled edges and then wedged it between floor and ceiling.  Maybe this will give you some more ideas.  I stapled stretchy fabric that i covered my absorbers with over the frame first.  The wedges just set on one another floor to ceiling.

I was thinking of doing something very similar. Since 703 is more rigid, it seems to hold up from the weight of the sections above it. The Safe and Sound or Pink Fluffy will have this ability and require some sort of "shelf" to hold the weight to keep the lower levels from compressing. I thought about using a 1x2 to build some framing on the wall, but I hate to put that many holes in the sheet rock.

[Big Red Machine]

If I have spackle and a can of the paint then I feel less concerned.  I learned to patch walls quite a bit when I was continually modifying my room. 

[jlafrenz]

I've patched plenty of holes from my various projects. That is partly why I try and create my designs to use fewer holes 

[murphy11]

Would bass traps always help in corners? I read somewhere about making bass traps out of Armstrong 933 ceiling tiles (2x4 Acoustical NRC .55/CAC .35) and I made 4" thick 18" traps in the corners of my basement. I'm not sure how to evaluate how effective they are. I've taken a bunch of measurements and waterfall plots don't necessarily get 'better' the thicker I go. (could be the material; admittedly my home made traps are not the norm) I also made 2" thick panels of 933 at reflection points; wondering if OC703 is the way to go.

I have 2 peaks of 4 db at 80 and 200 on my left speaker and am not sure if OC703 super chunks would be better than what I currently have. They seem easy enough to make. 

BRM, did you measure before and after super chunks and if so what difference did they make?

[bpape]

They won't always help.  It depends on what else is in the room, where your problems are coming from, etc.  And yes you want to maintain as much symmetry with the setup and treatment as possible, at least in front of you.

I would want to find out where the peaks are coming from before you go to far.  2" is bare bare minimum and not thick enough at side or front reflections to address some of the boundary related phase issues that can occur.

[murphy11]

Brian, your advice about symmetry was really helpful! I was getting bummed about my left speaker measuring a lot different than my right. It never occurred to me that I was part of the symmetry equation during the measuring process - light bulb moment!  My left waterfall was a lot worse because I was kneeling on the left side of my laptop for both left and right measurements.

When I measured the left speaker from the right side of my laptop well away from left, the waterfall got significantly better. I was thinking that I would have to spend a lot of money on OC703 to fix the room but I'm going to try to live with it for now. Also, your suggestion of going more than 2" on reflection points helped as well. OMMV because I am using Armstrong ceiling tiles because of availability, but thanks again for the suggestions!

[jk@home]

Interesting idea. I would think that a staple would hold in a wall if it only had a couple layers of material on it. That may become a lengthy process though. I have been thinking more along the lines of framing it out into 3 sections and using peg board as the shelf.

Well I figured if I use R-30 @ 9" thick, a support every two layers would be around 18" apart, so not too bad for my 81" height. Or maybe go three layers, from the posts at Gearslutz, support is needed every few feet or  so.

Someone over there had suggested bird netting for support, so think I will cruise down to the big box store and check that out. Then use three thin wood furring strips (two on the front edges, one in the back corner) vertically mounted to the walls. And staple the support netting horizontally to that. Netting or fabric could then also be stapled vertically down the front face.

From what I understand, one should used un-faced insulation, as the paper craft may cause lesser performance.

[jlafrenz]

I got side tracked from this project over the spring and summer months and have decided that I need to get focused on it once again. I do have a few more questions that I hope can be answered here.

I am leaning toward using Roxul Safe N Sound to build superchunk style traps. What width do I need to have span the corner for this? Using a 2' x 2' piece I can either get 2 with a faced of close to 34" or 4 pieces with a face of 24". With a 24" face, will Safe N Sound or pink fluffy be best? Does the same hold true when stepping up to a 34" face?

Would a membrane over the front of the superchunk be beneficial? If so, what is a good material to use?

[Ethan Winer]

I got your PM, and if you have further questions please PM me again. I cut way back on my forum activity last year while I prepared to perform a solo concert with the local symphony. So I haven't been visiting here or most other forums every day any more.

Fluffy insulation is fine, and a 34-inch wide face is vastly better than 24 inches if you have the room. You could stick thick paper or thin cardboard in front of the insulation if you want it to absorb less mid and high frequencies.

--Ethan

[jlafrenz]

Thanks Ethan. I need to determine if I will be able to go with the 34 inch wide face in this area or not. Space is a bit limited with equipment and layout. In the event that I can only go with a 24 inch face, is the Roxul or pink fluffy going to yield better results? It seems that either would benefit from some sort of membrane. Is ram board too thick?

[Ethan Winer]

As far as I know Roxul is basically the same as fluffy fiberglass, so use whichever is less expensive.

I don't know what ram board is. I've used thick paper and card stock with good results.

--Ethan