Which is the right Rock Wool?

[Jorg]

Im about to order some Rock wool for Acoutic treatment and improvement.

I will use it for DIY Bass Traps and HF+HM absorbtion.

I remember that Ethan Winer said here that you should buy rigid Rock Wool with a density between 40kg and 90kg (per sqaure meter).

The insulation company around my corner sells:

60kg and 100kg.

Is 100kg even better or is it already too much??
Im just not sure if Ethan just gave a rough guideline and if "the thicker-the better" is the rule of thumb or if u actually should be within his given numbers.

Ethan, are u maybe here to help??

[wreck]

Try heading over to Ethan Winer's forum over at musicplayer.com. I think you will find you're answers over there.

[Youn]

'thicker is better' is not the rule. 100kg is not too thick though IMO, but if you can get between 40 and 90 then just do that. For corner bass traps in smaller rooms, chech out studio tips "corner chunk" solution... http://forum.studiotips.com/ (can't find the exact link) It basically triangles of rockwool stacked up ontop of each other from floor to ceiling, or across ceiling, etc... cover with some porous, breathable, clothe, and you are in pretty good shape in terms of dollars per performance.

[Youn]

[Jorg]

Wow, thatnks for that link!

Whats inside that triangle? Air? Or is it filled with rockwool?

[Riad]

Originally Posted by Jorg

Wow, thatnks for that link!

Whats inside that triangle? Air? Or is it filled with rockwool?

Looks like triangle pieces cut to fill in the entire corner for bass trap.

Check out John Sayers website here: John Sayers

[Jorg]

Ive been quite a few times to the John Sayers page. They are really helpful with room layouts but once u talk about acoustic treatment of an existing environment, it calms down a lot.

To Those bass traps in that pic:

I always thought that the air cavity behind those rockwools would increase the bass absorbtion rather than filling it up completely........??? I might be very wrong though.

[Youn]

To have 1-2 inches of air space would help more when hanging a single layer of rockwool along walls, I don't believe it would have much of an improvement for a chunky bass "trap" like this, which is indeed solid rockwool throughout (rockwool ussually comes in 4x2 foot sheets so cut them in half for 2x2 then in half again diagonally to make the triangles and stack em like pancakes)

[Jorg]

Originally Posted by Youn

To have 1-2 inches of air space would help more when hanging a single layer of rockwool along walls, I don't believe it would have much of an improvement for a chunky bass "trap" like this, which is indeed solid rockwool throughout (rockwool ussually comes in 4x2 foot sheets so cut them in half for 2x2 then in half again diagonally to make the triangles and stack em like pancakes)

That sounds like a great idea if it works!
The reason why I was asking is that Ethan Winer was talking about the gap on this page:
http://www.ethanwiner.com/acoustics.html#top

He suggested this design for a bass trap:



I guess he might have suggested it cause its a lot cheaper than the other "triangled" option!

Damn, I wish I had the money to pay someone to do it for me. This is more frustrating than any mix I've ever worked on...

[Nuuk]

check out the forum.studiotips.com guys. they are usually very helpfull and have a good faq that usually covers a lot of the questions.

[jdunn]

Gee, and here all this time I thought Rockwool was used for, ummmm....... horticulture. I'm sure Ethan is real smart and all, but I would not want a bunch of Rockwool on my walls. It's very bad to breathe that stuff too. Little tiny evil fibers.

My acoustic designer uses something called Codel, which can be bought in a roll. He says it's less aggressive than fiberglass.

[Jorg]

Originally Posted by jdunn

Gee, and here all this time I thought Rockwool was used for, ummmm....... horticulture. I'm sure Ethan is real smart and all, but I would not want a bunch of Rockwool on my walls. It's very bad to breathe that stuff too. Little tiny evil fibers.

My acoustic designer uses something called Codel, which can be bought in a roll. He says it's less aggressive than fiberglass.

Like u mentioned urself:

Theres a big difference between Rockwool and Fiberglass.
Rigid Rockwool (which we are talking about) is compressed dense Rockwool and should - once installed - not set any particaly in the air. Additionally all your Rock wool will be covered with acoustic transparent cloth.

Theres no way that I'd put fiberglass at my walls!!!

[norman_nomad]

Originally Posted by Jorg

Im about to order some Rock wool for Acoutic treatment and improvement.

I will use it for DIY Bass Traps and HF+HM absorbtion.

I remember that Ethan Winer said here that you should buy rigid Rock Wool with a density between 40kg and 90kg (per sqaure meter).

The insulation company around my corner sells:

60kg and 100kg.

Is 100kg even better or is it already too much??
Im just not sure if Ethan just gave a rough guideline and if "the thicker-the better" is the rule of thumb or if u actually should be within his given numbers.

Ethan, are u maybe here to help??

Thicker is not "better". Dense rock wool will actually start to reflect low frequency energy rather than absorb it.

The whole concept behind mounting traps with a space behind them is so that the bass can travel through the bass trap (porous) , bounce off the wall (hard/reflective), then travel BACK THROUGH the bass trap, effectively absorbing the same sound energy twice before it is reflected back at the listener.

It's probably best to use bass trap combinations of different densities and physical thickness throughout your room.

And like a good mix, you'll probably need to do a lot of tweaking to get everything just right!

[Jorg]

Originally Posted by norman_nomad

Thicker is not "better". Dense rock wool will actually start to reflect low frequency energy rather than absorb it.

The whole concept behind mounting traps with a space behind them is so that the bass can travel through the bass trap (porous) , bounce off the wall (hard/reflective), then travel BACK THROUGH the bass trap, effectively absorbing the same sound energy twice before it is reflected back at the listener.

It's probably best to use bass trap combinations of different densities and physical thickness throughout your room.

And like a good mix, you'll probably need to do a lot of tweaking to get everything just right!

Nice one!!

I basically read the same thing:
Absorbtion is taking place when the sound travels inbetween different materials:
So maybe I could use those 60kg outside, leave some space and then a smaller 100kg strip inside, which is still spaced a bit from the wall??

I guess its like u said:
Get all the materials here and then try!!

[jdunn]

Listening is the key. My friend suggested I do the following in preparation to build some panels for my room.

"Listen for the bass build up and report back to me."

So I did, and it's all in one of the rear corners. The opposite rear corner has no bass, and this one has it all. Obviously the bass waveform is travelling along the walls to the furthest point it can, that corner.

So it looks like that corner will get a massive chunky bass trap. I'll ask him what he thinks about the rockwool.

His last job consisted mainly of ripping out bass traps that someone else had built and installed.

[Youn]

Originally Posted by norman_nomad

Thicker is not "better". Dense rock wool will actually start to reflect low frequency energy rather than absorb it.

You mean "denser in not better". Thickness ussually refers to dimensions. A single layer of rockwool ussually is 1 or 2 inches thick, and does jack shit to any frequency other then highs, while SuperChunks configuration goes upto a foot or more (depending on the cut of course) and does a helluva lots more to absorb low end energy. Don't think you will gain much definition with the single layer method, it'll only get rid of some livelyness and will leave things sounding muddy and unbalanced (like the previous poster described his room) Also, you will want to treat every corner equally. Sound travels everywhere, in the corners bass especially is noticably bad because as it reflects off the wall it collides or combines with itself either boosting or canceling itself out to some degree. It's like an audio clusterfuck, and it's a mess. Ever notice the wierd phase effect while walking around a live room or stairway while talking?

EDIT: That was sorta a piss poor explenation I just made, sorry to those folks more knowledgable then me.

[norman_nomad]

Originally Posted by Youn

You mean "denser in not better". Thickness ussually refers to dimensions. A single layer of rockwool ussually is 1 or 2 inches thick, and does jack shit to any frequency other then highs, while SuperChunks configuration goes upto a foot or more (depending on the cut of course) and does a helluva lots more to absorb low end energy. Don't think you will gain much definition with the single layer method, it'll only get rid of some livelyness and will leave things sounding muddy and unbalanced (like the previous poster described his room) Also, you will want to treat every corner equally. Sound travels everywhere, in the corners bass especially is noticably bad because as it reflects off the wall it collides or combines with itself either boosting or canceling itself out to some degree. It's like an audio cluster****, and it's a mess. Ever notice the wierd phase effect while walking around a live room or stairway while talking?

EDIT: That was sorta a piss poor explenation I just made, sorry to those folks more knowledgable then me.

Yes... thank you for making the distinction. I meant "denser" not "thicker".

Here's a good link to check out how "thicker" fiberglass affects a rooms frequency characteristics.

http://www.ethanwiner.com/density/density.html

[jdunn]

Originally Posted by Youn

Also, you will want to treat every corner equally.

I've got lots of bass in one rear corner, and none in the other rear corner. You're saying I should treat them equally?

I'm not sure.

[denial]

Tontine Fibres make absorption bats and we chose these over Rockwool based on our acousticians plans. The Tontine bats don't break down over time and they aren't bad for your health as they're made from polyester wool rather than fibreglass.

We used tontine Acoustisorb 3 bats for the entire control room. Never again will I use Rockwool.