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Drilling Large Holes in First Reflection Panel Frames?
Old 3 weeks ago
  #1
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Drilling Large Holes in First Reflection Panel Frames?

My room is just under 11 feet by 21 feet with 8 feet ceilings.

I just purchased the wood I need to build 16 panels in my mixing room. It's pine.

Of these, I was going to put together 6 panels made from 1x10s (actual dimensions 3/4 x 9 1/4). Four of these are for the first reflection points on the sides and two are going to be for the back wall in between my bass traps. This seem pretty thick for panels just looking at the boards, but I wanted to put 3 layers of Safe n Sound in these as I've read that thicker is better for first refection panels - so hopefully this is OK. This will make the panels 9 inches.

I'm wondering if it's worth drilling large holes in the sides of these panels. Maybe using a hole saw of about 4 inches in diameter on both sides as well as the tops and bottoms of each panel. Is this extra work worth doing? Or should it be avoided on first reflection absorbers?
Old 2 weeks ago
  #2
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Am I understanding correctly that the wood is to be used as a frame to contain the fibreglass?
What sort of covering do you have over the fibreglass?
Could you post a drawing of what you have in mind?

Not sure why you want to drill holes. in an open face absorption panel.

Cheers,

Tim
Old 2 weeks ago
  #3
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Quote:
Originally Posted by spirit View Post
Am I understanding correctly that the wood is to be used as a frame to contain the fibreglass?
What sort of covering do you have over the fibreglass?
Could you post a drawing of what you have in mind?

Not sure why you want to drill holes. in an open face absorption panel.

Cheers,

Tim
Thanks Tim. Apologies, I should have put more details in here.

I was going to make six 9 inch thick 24x48 broadband absorbers using 1x10 knotty pine frames in order to house three layers of 3 inch Rockwool Safe and Sound batts. Two for each side at the first reflection points (four total) and two for the back wall in between the bass traps (although maybe I don't need them as thick at the back wall). Since the true dimensions of the wood is 9 1/4 I was going to cut 1/4 of an inch off the boards and seal the back with thin plywood to hold the batts in place and add some strength. I was then going face Guilford of Maine fabric over the units and mount them flush to the wall.

I've seen some folks cutting large holes into their frames with the claim there's more absorption, with holes spaced down the sides, tops and bottoms of each frame, so I was thinking of doing the same (4 inch diameter holes with a hole saw) since these panels are going to be pretty thick.

But I don't know if it will add much value over all and if it's worth the time doing?

I've attached a picture example I found in Google images.


Hope this makes sense,

Cheers.

Drak
Attached Thumbnails
Drilling Large Holes in First Reflection Panel Frames?-panelholes.jpg  
Old 2 weeks ago
  #4
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Most amateurs first complain that high end absorption is too high.

How does your room look with no ceiling? Obvious from no ceiling early reflection point absorbers.
Old 2 weeks ago
  #5
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Ahh, I see what you are suggesting.
It’s pretty simple, a 4” hole exposes roughly 12 square inches of absorption. Your 24 x 48 panels have about 100 x more area. So each hole increases the panel’s absorption area by about 1% - your call ....drilling, sanding, painting...

Also, don’t forget André’s point about 1st reflection points on the ceiling.
Front walls too because your monitors will radiate.
You will want something on the back wall - between corner bass ‘traps’ is common as you’be described.
Sounds like you’ve got a good general starting point.
Try to keep the design flexible if you can, so that you are able to fine tune the treatment going forward.
That’s one problem with building the framed absorbers; they kinda lock you into a certain layout.

Cheers,

Tim
Old 2 weeks ago
  #6
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Quote:
Originally Posted by spirit View Post
Ahh, I see what you are suggesting.
It’s pretty simple, a 4” hole exposes roughly 12 square inches of absorption. Your 24 x 48 panels have about 100 x more area. So each hole increases the panel’s absorption area by about 1% - your call ....drilling, sanding, painting...

Also, don’t forget André’s point about 1st reflection points on the ceiling.
Front walls too because your monitors will radiate.
You will want something on the back wall - between corner bass ‘traps’ is common as you’be described.
Sounds like you’ve got a good general starting point.
Try to keep the design flexible if you can, so that you are able to fine tune the treatment going forward.
That’s one problem with building the framed absorbers; they kinda lock you into a certain layout.

Cheers,

Tim
Thanks for the replies, everyone.

I'll think about adding holes to the frames. Probably not be worth it in the end. I won't be painting the wood though - I'll pull the fabric over the front, all sides and staple on the back of each panel, so potential holes would be covered with acoustic fabric as well.

There will be a cloud above, but since the ceiling is 8 feet I was thinking of a 6 inch thick panel(s) here with 2 layers of safe n sound instead of 9 inches. The other option is to purchase some pre-made panels for the ceiling (such as GIK 244's) but I'm not sure here yet. Was just thinking about floppy safe and sound and gravity being a problem, although the fabric on the panel would be pretty taught.


For the remainder of the room (where needed) including the front walls I was also going to go with 6 inch thick panels, although maybe they should be thicker at the front wall as well? I could do 9 inches there too if more appropriate.

I already made column style (or soffit style) bass traps that I installed in each corner from floor to ceiling. These are filled with 18x18 inches of safe n sound. I went ahead and did this without any sort of testing, figuring they'd be required anyway. I also needed to get the massive pile of insulation sitting on my studio floor (I reclaimed the insulation from another project I did for a jam space) out of the way

REW is something I'm looking at right now. I have no clue how to use it but I'll do some research and attempt some testing before I get too deep into it.

Cheers,
Drak
Old 2 weeks ago
  #7
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Keeping it short, 8" is the MINIMUM DEPTH I nd many others recommend for porous absorbers.
Old 2 weeks ago
  #8
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Quote:
Originally Posted by avare View Post
Keeping it short, 8" is the MINIMUM DEPTH I nd many others recommend for porous absorbers.
I should go three layers and create a 9 inch total set of panels for the cloud as well then.

But budget wise and materials wise - after I do the 9 inch panels for all the reflection points (including ceiling) I only have enough insulation left for 6 inch thick panels where needed on the remainder of the room.
Old 2 weeks ago
  #9
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Quote:
Originally Posted by Drakaland View Post
But budget wise and materials wise - after I do the 9 inch panels for all the reflection points (including ceiling) I only have enough insulation left for 6 inch thick panels where needed on the remainder of the room.
I have no idea what your budget and what is a separate material, is.

you want a good result, you are getting the right advice. As it is I do not even know which cost saving options to present I have no data to work from.
Old 2 weeks ago
  #10
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Quote:
Originally Posted by avare View Post
I have no idea what your budget and what is a separate material, is.

you want a good result, you are getting the right advice. As it is I do not even know which cost saving options to present I have no data to work from.
Hi André,

I purchased enough wood material for about six 9 inch thick panels for the reflection points (using 1x10's). So enough material here for four 9 inch thick panels (two on each side of the work desk) and now for the cloud above.

The rest of the wood I purchased are 1x8's (really 3/4 x 7 1/4) for 6 inch thick panels for the rest of the room (I was going to rip them down into 6 inch boards to fit 2 layers of safe n sound). I have enough wood here for 10 panels (to start) at 6 inch thickness for the rest of the room.

But, I could modify the 1x8s with some creativity to make it so they will also house 9 inches of insulation. Such as ripping them down into 3 inch wide pieces then gluing a 3 inch a wood spacer with some hardware between the ends of the boards at the top, middle and bottom. If that makes sense.

I did up a quick diagram below in paint as an idea. I don't mind spending the time and modifying in order to do this project properly.

Cheers,
Drak
Attached Thumbnails
Drilling Large Holes in First Reflection Panel Frames?-panelmodify.png  
Old 2 weeks ago
  #11
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7.5" is close enough to 8". Mount the insulation with a 1.5" gap at the back.

Enjoy!
Old 2 weeks ago
  #12
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Quote:
Originally Posted by avare View Post
7.5" is close enough to 8". Mount the insulation with a 1.5" gap at the back.

Enjoy!
That's a better idea. I shall do that then on the remaining panels!

Cheers!
Drak
Old 2 weeks ago
  #13
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I know this is off topic regarding my original post.

I'm going to face these panels with GOM fabric, but I was curious about keeping the fibers of the Safe n Sound in place when the time comes to moving panels around or moving them to another location if we re-locate over the next few years. Then there's the ceiling cloud, gravity etc.

Is facing these panels with a cotton batting material before the final layer of GOM, worth doing? Or would it cause potential issues with absorption?

Amazon sells cotton batting for quilts etc. that isn't badly priced.
Old 2 weeks ago
  #14
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I recently built a bunch of panels, somewhat thinner than yours but same type of concept - I even wondered about drilling holes all around the frames with a hole saw, but ultimately decided it wasn't worth the extra work for me.

I wasn't really worried about the fibers getting loose, but I chose to use cotton (edit: polyester) batting to help smooth out around the edges and to make it easier to stretch the fabric fairly tight around my wooden frames. In my opinion, I would not recommend skipping the batting because it helped a ton with getting the outer GOM fabric to look nice. It will not negatively affect absorption. The way I understand it, such a thin and loose material like cotton or polyester batting could only have any impact on very high frequencies, which your insulation is already completely absorbing.
Attached Thumbnails
Drilling Large Holes in First Reflection Panel Frames?-img_8384.jpg  

Last edited by zakofalltrades; 2 weeks ago at 05:53 PM.. Reason: clarification - polyester batting
Old 2 weeks ago
  #15
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Quote:
Originally Posted by zakofalltrades View Post
I recently built a bunch of panels, somewhat thinner than yours but same type of concept - I even wondered about drilling holes all around the frames with a hole saw, but ultimately decided it wasn't worth the extra work for me.

I wasn't really worried about the fibers getting loose, but I chose to use cotton batting to help smooth out around the edges and to make it easier to stretch the fabric fairly tight around my wooden frames. In my opinion, I would not recommend skipping the cotton batting because it helped a ton with getting the outer GOM fabric to look nice. It will not negatively affect absorption. The way I understand it, such a thin and loose material like cotton batting could only have any impact on very high frequencies, which your insulation is already completely absorbing.
Hey nice looking panels! They look similar to the colors I'll be using, black and grey (FR701 Grey Mix or Blue Papier).

For the first cotton batting layer, did you wrap the panels in batting the same way you did the GOM (wrap it sort of like a present)?

Also, do you mind me asking where you got the cotton batting, and how thick it is? Will polyester batting work just as well? I've seen some posts with people talking about Dacron and I guessing it's the same thing.
Old 2 weeks ago
  #16
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I’ve never had a problem with the fiberglass bulging out over time. But if I use FG batting I generally keep it set back from the fabric. If I want it tight against the fabric, I tend to use rigid boards like OC703 etc.
Make sure there is a good friction fit regardless.
You can retain the FG with light gauge wire cross-crossed across the face too. That works well for clouds.
Old 2 weeks ago
  #17
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Quote:
Originally Posted by spirit View Post
I’ve never had a problem with the fiberglass bulging out over time. But if I use FG batting I generally keep it set back from the fabric. If I want it tight against the fabric, I tend to use rigid boards like OC703 etc.
Make sure there is a good friction fit regardless.
You can retain the FG with light gauge wire cross-crossed across the face too. That works well for clouds.
I was thinking more along the lines of the fibers coming out into the room from a cloud hanging above.

Just being overly cautious I guess. I started looking into forum searches and noticed some people use Dacron to face their panels before the fabric for this reason.

I'm based in Canada, and I'm wondering if this is the same thing as Dacron.

I don't mind taking these extra steps.

https://www.amazon.ca/gp/product/B00...K6Y9EEQB&psc=1
Old 2 weeks ago
  #18
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Thanks! I actually did use polyester batting, my apologies. I'm sure either would work, but I preferred the polyester for my panels because a synthetic material like polyester will resist mildew over time, whereas a natural fiber like cotton may be susceptible to mildew. From my understanding, Dacron is the same as polyester batting. I can tell you from my experience that even though I don't really think there is any problem with fibers falling out even without the batting, it definitely adds an extra layer that will ensure no fibers come loose into the room.

I don't know exactly how thick the batting measures, probably something like 1/8" or 3/16" - but anything light to medium loft would work. I got it on Amazon, but you may be able to find better prices on it at a local fabrics or craft/hobby store. I did indeed wrap the frames with the batting the same way as the GOM fabric, just like a present! It's an extra step that takes more time, but I think it is worth it in the end because it made the outer fabric very easy to wrap and make it look nice without any fuss, plus the added security of knowing the fibers are contained sufficiently.
Old 2 weeks ago
  #19
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while I understand your concern, I’ve just not seen any significant shedding over the years. I’ve never had a client complain of this (they sometimes complain of off-gassing ).

One provisio, Rock wool (Roxul) tends to produce a lot of dust and debris. While we use it inside walls, I find it messy for treatments. But I think you mentioned Safe and Sound - a much tidier product.

I would advise against Dacron, if you can’t be sure of it’s acoustic impedance. That’s why we use fabrics like the FR series.

Cheers
Old 2 weeks ago
  #20
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Thanks for all the replies. It's been really helpful.

I have just one more question, I promise (at least for now )

Is it OK to build my frames slightly snug? For instance, the Safe'nSound is 47 inches long. So is it OK to build the long side of the frames at 46.5 or 46.75 instead of the exact length of the safe n sound? I know you shouldn't compress this stuff but I wasn't sure compressing by 1/2 an inch or 1/4 of an inch total would matter too much (would end up compressing the ends by 1/4 or 1/8 at each end).

Hope this makes sense. Would make for a slightly more snug fit, especially on the cloud.
Old 2 weeks ago
  #21
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it’s perfectly fine to undersize it a bit. It helps to retain it in the box, esp. when ceiling mounted.

Cheers,
Tim
Old 2 weeks ago
  #22
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Quote:
Originally Posted by spirit View Post
it’s perfectly fine to undersize it a bit. It helps to retain it in the box, esp. when ceiling mounted.

Cheers,
Tim
Looks like the batts are 47.5, so they give that extra half inch anyway. I just ended up going with a 47 inch cut for the side pieces.

Thanks for all your help on this stuff. It's going to be awhile but hopefully I'll have the frames all built by the end of the week.

Cheers,

Drak
Old 5 days ago
  #23
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Welp - it was a stupid amount of extra work and I went through 2 hole saw blades, but I decided to put holes in all my pieces anyway, before making them into frames. I also ended up laminating pieces together with glue and screws so all my frames are the same dimensions. I put together 18 frames. I just have to put on the back braces on now, put in the insulation and do the fabric work, which I'll do in a few weeks.
Attached Thumbnails
Drilling Large Holes in First Reflection Panel Frames?-panelframes.jpg  
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