[Red Dragon Audio]

Sorry....don't mean to be anal, but this just jumped out at me.

wayyy off.  How embarassing.  
I've corrected my post.

[Glenn K]

Finally! I placed my order today on Rock wool 2ft x 4ft panel from a distributor in Houston, the price I paid were:

8 PCF, 2" thickness @ $0.4 per ft2

4PCF,  4" thickness @ $0.7 per ft2

I bought a total of 18 panels of 8PCF 2" and 6 panels of 4PCF 4". The total cost is $91.20 + 8.25% tax.

I will stack 2 pieces of 8 PCF 2" to make one 4" panel for bass traps. I will use the 4PCF 4" panels to treat first reflection points.

That's a total of 9 bass trap panels and 6 reflection point p ...

>I read somewhere that Mineral Wool may cause less itchness than fiberglass. I wonder if anyone can confirm this? <

Not so sure about that.. The nice thing is the stuff will not kill you but you are going to wish you where dead after making 9 of them.. ha ha ha Just kidding it is not so bad..
Here are a couple tips:
1) build them outside to keep the dust from you
2) Wear gloves, hat, glasses, long shirt and of course pants.
3) Take a good shower after you are done..

Good luck on the panels.

Glenn

[Glenn K]

8#
5#
3#

is short hand for

8.0 PCF
5.0 PCF
3.0 PCF

PCF = Pounds per Cubic Foot
The higher the number the greater the density.


Therefore 8.0-PCF is 37.5% more dense than 5.0-PCF and 62.5% more dense than 3.0-PCF.


While 5.0-PCF is 40% more dense than 3.0-PCF

I'm aware of all this.  I'm not asking for evidence that 8# is denser than 5# or by how much, I'm asking how do we know th ...

hey Paul,

I think Bryan is one of the smartest guys on the forums but I think he is not right about the 8 pound.. But just to make sure just use the 6 pound and all will be good..

[bpape]

Still looking for it.  I know I've read it in several studies - just have to find it.

[bpape]

Haven't found the official studies yet but here are a couple of other threads where this is discussed.  Knightfly has been doing this a LONG time.

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=3998&postdays=0&postorder=asc&start=0

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=5503

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=5401

[Glenn K]

I am not doubting you or John, but when I talk into 8 pound (you know the old talk test) I don't hear a thing coming back..... But like I said if you feel as though it is not good for first reflections then use the 4 or 6 pound...
Just a side note and don't tell Bryan, I have 8 pound on my first reflections and it sounds great..

Glenn

[bpape]

Don't get me wrong - it's absolutely better than nothing and for the majority of the reflections it will work just fine.

It's when you have really shallow angles and also for general ambience control where you have sound hitting it from all angles that the difference will show.

I did find a couple of the articles but of course, now they want $50 for a download - they used to be free     If anyone is really interested, in the theory, you can google on grazing effect.  You'll get all kinds of stuff regarding metal grating, sea beds, lasers, microwaves, etc.  You'll also find a lot of acoustics papers that make mention of the 'grazing group' and the non-grazing group.  The papers that are in question are the ones that DEFINE it.