Rockwool RW5 or RW3 for bass traps?

[hilander74]

hi,

I'm putting some bass traps together for my (almost square) room which is 11' 11" x 11' 6" x 8' 4". The room will be used solely for mixing, not recording.

I'm going to use rockwool as I can get it locally. I plan on putting some 6" thick traps in the front corners to start with and I'm wondering will RW3 (60kg/m3) or RW5 (100kg/m3) be most effective at that thickness.

I read somewhere on here that the denser RW5 is most effective at a thickness of 4" or so and any thicker reduces this effectiveness.
Is this true?

Also, with the rear wall about 7' behind the listening position, should I be looking at 6" thick traps on the wall or would 4" do? (along with the rear corners).
I'm sure someone else suggested diffusion might be a better option with the rear wall this close, is this true?
I'll be facing a large window with curtains, which I'm not really sure how to deal with (portable trap maybe).

I'll be putting 2" absorbers on the side reflection points too and hopefully treat the ceiling at some point (the floor is carpeted).

Apologies if this has all been done before, but after researching many threads over the past few days, (and I've learned a lot!) it has still thrown up some questions and I'd like to do this right.

Thanks.

[Glenn Kuras]

I'm going to use rockwool as I can get it locally. I plan on putting some 6" thick traps in the front corners to start with and I'm wondering will RW3 (60kg/m3) or RW5 (100kg/m3) be most effective at that thickness.

If your going to make them 6" thick then 60kg is fine.

Also, with the rear wall about 7' behind the listening position, should I be looking at 6" thick traps on the wall or would 4" do? (along with the rear corners).

Go with 6' as there are strong nulls and peaks coming from that area.

I'm sure someone else suggested diffusion might be a better option with the rear wall this close, is this true?

Your main focus in a room like yours is going to be absorption. Diffusion is fine but use it in the non main spots, like the back 1/3 side walls and ceiling.

I'll be putting 2" absorbers on the side reflection points too and hopefully treat the ceiling at some point (the floor is carpeted)

[hilander74]

great, thanks for the quick response Glenn, much appreciated!

[Glenn Kuras]

Originally Posted by hilander74

great, thanks for the quick response Glenn, much appreciated!

No problem. Let me know if you have any other questions.

[hilander74]

Ok so I've been offered 6x6 panels of 4'x1' Rocksil (Rocksilk?) for 20EUR a pack (of six).
The guy on the phone reckons(?) it's 45kg/m3 and 4" thick.
4'x1' didn't sound like an ideal size for framed traps so I'm thinking I could make superchunks with each panel making a 2' wide, 16" high chunk.
I'm having trouble sourcing Rockwool around here and it sounds like a decent price.

Is 45kg/m3 ok for making these kind of traps?

Also, how important is it to keep trapping symmetrical at the rear corners?
The front (behind my monitors) is no problem and I'm assuming this is more important with regards a balanced stereo image.
I've got a door in one corner at the rear, so I'm thinking of putting a framed trap on the door and one on the adjacent wall, like I've seen Ethan do in one of his youtube vids.

So would it be ok to put a superchunk style trap in the other rear corner or should I employ a similar framed trap method like with the door (or does it really matter much?)

[Glenn Kuras]

Is 45kg/m3 ok for making these kind of traps?

Yes

Also, how important is it to keep trapping symmetrical at the rear corners?

Not really, unless you are only a few feet from the back.

I've got a door in one corner at the rear, so I'm thinking of putting a framed trap on the door and one on the adjacent wall, like I've seen Ethan do in one of his youtube vids.

Should be fine.

[hilander74]

It turns out that stuff was 4'x2' as I thought it might be, and 38kg/m3 (4" thick).

As it's less dense would it make sense to press 2 panels flat into 4" or 6"?
How might this effect the absorption?
Can 38kg/m3 panels be used like this?

I'm gonna keep them as panels and do frames I think, as it would be very messy cutting it into superchunk triangles.
I only got 12 panels of the 38kg/m3 stuff as I found somewhere with RW3 and RW5. The 38kg/m3 was going so cheap I felt I had to grab a couple of bales.
Hope I can still make some use out of it.

[Glenn Kuras]

As it's less dense would it make sense to press 2 panels flat into 4" or 6"?

If you make them 6" you really will not need to press them together. Just stack them and cover in the frame.

[hilander74]

Thanks Glen.

After some further reading, I noticed some people are suggesting that superchunks might be a more efficient use of the lower density stuff as it wasn't so good at absorbing low freqs. but I guess if I'm putting 2 panels into 6 inches it should be ok.
Really nasty stuff too, I aint going near it without gloves and a mask!

[Glenn Kuras]

Originally Posted by hilander74

Thanks Glen.

After some further reading, I noticed some people are suggesting that superchunks might be a more efficient use of the lower density stuff as it wasn't so good at absorbing low freqs. but I guess if I'm putting 2 panels into 6 inches it should be ok.
Really nasty stuff too, I aint going near it without gloves and a mask!

With glasses, long sleeve shirt and so on.thumbsup