Kraft Paper: leave or keep?

How to use REW, What is a Bass Trap, a diffuser, the speed of sound, etc.

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saemola
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Kraft Paper: leave or keep?

Post by saemola »

Hey guys and gals,

I'm setting up my superchunk bass traps and my glass wool is all Kraft paper-backed.
Considering I'll be stacking triangles of glass wool from floor to ceiling without wood supports along the way, is it necessary that I strip the paper off, or can I leave it on as that would clearly be easier to work with?
What about cloud and side first point reflection absorber panels?
Gregwor
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Re: Kraft Paper: leave or keep?

Post by Gregwor »

Since sound waves don't just travel horizontal, you'll want to pull it off for your super chunks.

For the side walls, it depends on whether you need high end deflected back into the room. If have an air gap behind the insulation, and you have the paper on the rear side of the insulation, you will probably want to pull the paper off in order to take full advantage of the gap. If you have the paper on the front face of your insulation, again, that can be beneficial, or detrimental. It all depends on whether or not you need high end absorbed or not. Or maybe you only want some of the paper left on.

Greg
It appears that you've made the mistake most people do. You started building without consulting this forum.
saemola
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Location: Naples (Italy)

Re: Kraft Paper: leave or keep?

Post by saemola »

Thank you Greg.
I was basically asking whether the paper would have a noticeable impact on the sound and you seem to think so.
If that were the case thought, wouldn’t it be beneficial to have it on the super chunks since that isn’t a first reflection point and reflecting high end back into the room would be beneficial?
My doubt with leaving the paper on the super chunks had more to do with whether it would compress the wool underneath after the 40th layer is stacked up.
Gregwor
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Re: Kraft Paper: leave or keep?

Post by Gregwor »

wouldn’t it be beneficial to have it on the super chunks since that isn’t a first reflection point and reflecting high end back into the room would be beneficial?
For a front face piece of insulation, totally, if your REW test show that you need some high energy left in the room.
My doubt with leaving the paper on the super chunks had more to do with whether it would compress the wool underneath after the 40th layer is stacked up.
I doubt paper would create any notable weight difference when you're dealing with quite heavy insulation. I'd be more concerned with how the energy would be passing through the paper.

Greg
It appears that you've made the mistake most people do. You started building without consulting this forum.
saemola
Posts: 69
Joined: Sun Aug 28, 2016 12:15 pm
Location: Naples (Italy)

Re: Kraft Paper: leave or keep?

Post by saemola »

Gregwor wrote:I doubt paper would create any notable weight difference when you're dealing with quite heavy insulation. I'd be more concerned with how the energy would be passing through the paper.
Interesting. I assumed the paper effect on low frequency energy would be negligible.
Do you think glass wool is too heavy to just stack it up without intermediate "shelves"?

Basically I was planning on doing this:
Image

... rather than this:
Image

My ceiling is 3.4m or 11.15' high.
Soundman2020
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Re: Kraft Paper: leave or keep?

Post by Soundman2020 »

saemola wrote:Hey guys and gals,

I'm setting up my superchunk bass traps and my glass wool is all Kraft paper-backed.
Considering I'll be stacking triangles of glass wool from floor to ceiling without wood supports along the way, is it necessary that I strip the paper off, or can I leave it on as that would clearly be easier to work with?
What about cloud and side first point reflection absorber panels?
For the superchunks, I don't think it will make a large difference. At best, it would act like a foil, but since it is low mass, it would only affect the high-mids and highs, at best, not the lows. It will be pretty much transparent to the type lows that the device is dealing with. Especially considering that it will be laying horizontally, basically edge-on to the direct wave-front.

However, when used on walls or the cloud, there could be a difference, since those are aimed at mids and highs anyway. There's some evidence that it does act slightly as a membrane trap (Ethan Winer has documented that, if I recall correctly). Even so, this might not be bad thing in some cases: just not good on first reflection points.

In other words, it all depends on WHERE you use it, and for what purpose you are using it!

- Stuart -
saemola
Posts: 69
Joined: Sun Aug 28, 2016 12:15 pm
Location: Naples (Italy)

Re: Kraft Paper: leave or keep?

Post by saemola »

Soundman2020 wrote:
saemola wrote:Hey guys and gals,

I'm setting up my superchunk bass traps and my glass wool is all Kraft paper-backed.
Considering I'll be stacking triangles of glass wool from floor to ceiling without wood supports along the way, is it necessary that I strip the paper off, or can I leave it on as that would clearly be easier to work with?
What about cloud and side first point reflection absorber panels?
For the superchunks, I don't think it will make a large difference. At best, it would act like a foil, but since it is low mass, it would only affect the high-mids and highs, at best, not the lows. It will be pretty much transparent to the type lows that the device is dealing with. Especially considering that it will be laying horizontally, basically edge-on to the direct wave-front.

However, when used on walls or the cloud, there could be a difference, since those are aimed at mids and highs anyway. There's some evidence that it does act slightly as a membrane trap (Ethan Winer has documented that, if I recall correctly). Even so, this might not be bad thing in some cases: just not good on first reflection points.

In other words, it all depends on WHERE you use it, and for what purpose you are using it!

- Stuart -
I appreciate you chiming in Stuart.
That's actually more along the lines of what I was thinking.
Do you believe putting "shelves" at different points along the superchunk is more for stability or does it actually affect the absorption (as it supposedly avoids the bottom slices of wool not getting squashed)?
I'm asking cause I'd rather not drill into my drywall to place shelves unless I really have to.

Edit for folks who might have the same doubt
I ended up using the shelves method as the wool was getting compressed by about 37%. That sounds like way too much to me, both in terms of bass absorption efficiency and in terms of extra material necessary to fill each corner.
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