Some DIY Bass trap questions from a newbie

[maxxy]

Hi All,

Few questions. I'll keep it short I'd appreciate answers in laymen terms

1. Does rockwool lose its shape over time because it is fluffier than fibreglass? Anyone have experience in this?
2. The rockwool I purchased has a distinct odor that hasn't passed for quite a while. Is it ok to cover the rockwool in thin plastic wrap? Will this ruin the absorption properties?
3. In regards to #2, if I cover the rockwool in plastic wrapping I'm guessing that "breathable" fabric isn't much of a necessity, right?
4. Punching wholes in the sides of the bass trap frame - necessary or marginally better? I know this has been debated about but I would want to know if drilling holes in the wood is a beneficial spending of my time.
5. Fiberglass with aluminum facing (one side) - will it perform like the paper facing thingy? FSK I think it's called? Or should I go with plain?

Currently going to build a wooden frame (15cm deep) with 15cm 80kg/m^3 rockwool. I fear this might be a bit heavy to hang from the walls. 24-32kg/m^3 fiberglass a better option? This is a small room we're talking about (around 3m x 4m x 2.7m).

Thanks in advance

[PaulP]

Originally Posted by maxxy

1. In regards to #2, if I cover the rockwool in plastic wrapping I'm guessing that "breathable" fabric isn't much of a necessity, right?

Now there's a good question ! A lot of people apparently don't see a problem
with wrapping insulation in plastic but I don't see how air can interface properly
if you do. There is also the common recommendation to use fabric that breathes,
which makes sense to me.

A compromise that I've come up with which might be ok is to wrap with very
thin, very loose plastic so air can move a bit at the boundary (but you
wouldn't want to hear it flapping around either). It would be interesting
to know just how air does move in and out of insulation especially at low
frequencies. I've wondered how we can talk about gas flow if there is a
plastic barrier blocking the flow.

Paul P

[maxxy]

Hi Paul

Thanks for the reply. I guess that a thin plastic covering wouldn't stop the mid-lower frequencies but would reflect back higher frequencies that would then be re-absorbed by the fabric that is placed over?
I am just shooting in the dark here. I had an acoustics consultant come over to my place to check if it is according to construction standards (acoustic wise, of course). While he was here, he gave me some tips regarding building bass traps. He said covering the wool in a plastic wrap would still work for mid-low frequencies. I really have no knowledge in the field.

Considering this is a small room (and I wouldnt like it to be completely "dead") then still absorbing the mid-low frequencies would still be ideal.

Thoughts?

[maxxy]

bump for great justice?

[boggy]

Originally Posted by maxxy

Hi All,

Few questions. I'll keep it short I'd appreciate answers in laymen terms

Hi maxxy
I'll try

Originally Posted by maxxy

Does rockwool lose its shape over time because it is fluffier than fibreglass? Anyone have experience in this?

No, I think not. And... not all rockwoll are flufy and soft. There are denser and harder products manufactured from rockwoll.

Originally Posted by maxxy

The rockwool I purchased has a distinct odor that hasn't passed for quite a while. Is it ok to cover the rockwool in thin plastic wrap? Will this ruin the absorption properties?

If you dont have any other way to minimize odor... then cover it. Or try to find rockwoll that don't have any odor next time.

Originally Posted by maxxy

In regards to #2, if I cover the rockwool in plastic wrapping I'm guessing that "breathable" fabric isn't much of a necessity, right?

Breathable fabrics can't stop odor. Generally you don't need breathable fabrics at all.

Originally Posted by maxxy

Punching wholes in the sides of the bass trap frame - necessary or marginally better? I know this has been debated about but I would want to know if drilling holes in the wood is a beneficial spending of my time.

It's better to have this side holes.... but you may not drill it... if you like.

Originally Posted by maxxy

Fiberglass with aluminum facing (one side) - will it perform like the paper facing thingy? FSK I think it's called? Or should I go with plain?

I never use this for acoustics... and I'm pretty sure that I never will...

Originally Posted by maxxy

Currently going to build a wooden frame (15cm deep) with 15cm 80kg/m^3 rockwool. I fear this might be a bit heavy to hang from the walls. 24-32kg/m^3 fiberglass a better option? This is a small room we're talking about (around 3m x 4m x 2.7m).
.....

80kg/m3 isn't too heavy, IMHO. Use it in your small room... 24kg/m3 and 32kg/m3 is a bit too fluffy, weak and light for my taste


regards

boggy

[ciro]

Originally Posted by maxxy

Currently going to build a wooden frame (15cm deep) with 15cm 80kg/m^3 rockwool. I fear this might be a bit heavy to hang from the walls. 24-32kg/m^3 fiberglass a better option? This is a small room we're talking about (around 3m x 4m x 2.7m).

Thanks in advance

My room has similar size;

IME you don´t need a 80kg rockwool for a 6" (15cm) trap to be effective. I have 20 traps here, 6 are rockwool 64kg/m3, but most are 32 kg.They works pretty well.Just be sure to not make a 32 kg/m3 trap less than 6".
Using 6" with a 6" gap will be great on the rear wall.Thicker is even better.
Ciro

[maxxy]

Hi

Thanks for the replies. As I understood, I don't need breathable fabrics for corner bass absorbers?

Should I purchase 60kg/m^3 for the corner absorbers as I've already bought 80kg/m^3 (which I can perhaps put on the parallel walls instead)?

Can Glenn perhaps chime on which fabric they use to make the Art Panels? I hope you don't mind I am interested in printing some kind of image on the fabric to make it girlfriend friendly.

BTW, is there any need to put diffusers in such a small room? It's basically my living/projector room and there's not much space to move stuff around. The listening position is right up near the wall (need distance for the projector).

[maxxy]

Bump :(

Can someone answer quickly...
I'm building 15cm (6") deep traps for corners

I have access to the following material: Which would be best?
60, 80, 100 kg/m^3 rock wool (plain)
10, 12, 16, 24 kg/m^3 fiber glass (plain or aluminum backed)

Cheers

[avare]

Originally Posted by maxxy

I'm building 15cm (6") deep traps for corners

I have access to the following material: Which would be best?
60, 80, 100 kg/m^3 rock wool (plain)
10, 12, 16, 24 kg/m^3 fiber glass (plain or aluminum backed)

60 kg/m3 rock wool. Have fun!

Andre

[maxxy]

Thanks a lot! Appreciate it