[toobluvr]

Was wondering if anyone has experience with this stuff:

http://www.insulationworld.com/prodView.asp?idproduct=631

They also have 1.5, 3 and 4 inch thickness.
81 cents per s/f for 2" thick seems very reasonable compared to the OC 703 and 705 prices I've seen.  The 4" stuff is $1.62 per s/f.
And likewise, the 3" is double the 1.5" price per s/f.

And I'm hoping you don't need to buy a truckload to obtain some!

I did a little research on "mineral wool" and have learned there are 3 different types:
"glass wool," or "fiberglass," made from recycled glass or silicates;
"rock wool," made from virgin basalt, an igneous rock; and
"slag wool," made from steel-mill slag.

Anyone know which material is best for acoustic panels?

I'm looking to make panels for first reflection points, corner bass traps, wall behind the listening postion, and maybe ceiling-wall boundaries.  Any thoughts on what thicknesses and densities would be appropriate for each?  Or if this stuff is even a good substitute for 703 / 705?

Overall, I am getting balanced and very good sound right now, but I'm just looking to clean things up a bit and get some better focus.  Just lucky I guess, since I have what on the surface, would appear to be a VERY difficult room:  
* speakers are located right underneath a ceiling height change from cathedral-to-normal, and are firing into the low-ceiling area.
* wide open spaces behind the speakers; a more "conventional" room between speakers and listening seat.
* non-symmetrical sidewalls......staircase on one.
* non-symmetrical corners...one rear "corner" is actually a doorway to kitchen
* Openings to staircase, front door, and kitchen

These features are clearly illustrated by the photos in my gallery (album is titled "Winter 2006").  Any input / advise from the experts here on how to "tune" this room is welcome and greatly appreciated.

Thanks,
John

[klh]

I'd say 2" panels spaced 2" from the wall for flush mount locations and 4-6" panels for cross corner bass traps (so one 4" panel, two laminated 2" panels, two laminated 3" panels or 3 laminated 2" panels). ~3-4 pcf for the flush mounts and 6-8 pcf for the bass traps seem to be the standard.

[95bcwh]

What are the density of these panel?

I can find in a local distributor of mineral wool panels, they sell 2ft x 4ft panel, 4lb/ft3, 4 inch thick, the cost is $0.7 per square foot.


klh,
  For bass trap purpose, if I double up the 4 inch panel to make an 8 inch, do you think I can use 4lb/ft3? Or I still need 6lb/ft3 and more?

[klh]

That would be just as effective is a 4" panel with a density of 8pcf. If you can handle an 8" trap across a corner, I would think that would work very well.

[bpape]

The material that was linked to is 8lb/cu ft density.  This, IMO, is not acceptable for side wall reflection point usage.  It's too dense and will actually case higher frequencies to reflect when hit at shallow angles - like you'll get on a wall for the sides.  

For bass control in the corners, it's a fine product.

[randytsuch]

The material that was linked to is 8lb/cu ft density.  This, IMO, is not acceptable for side wall reflection point usage.  It's too dense and will actually case higher frequencies to reflect when hit at shallow angles - like you'll get on a wall for the sides.  

For bass control in the corners, it's a fine product.

What density do you recommend for reflection control?
I was thinking about 6 lb, since I could use that for bass traps too.

Randy

[toobluvr]

The material that was linked to is 8lb/cu ft density.  This, IMO, is not acceptable for side wall reflection point usage.  It's too dense and will actually case higher frequencies to reflect when hit at shallow angles - like you'll get on a wall for the sides.  

For bass control in the corners, it's a fine product.

Thanks!
Would you know if the other thicknesses are 8 lb as well?

see them here:

http://www.insulationworld.com/prodList.asp?strSearch=mineral+wool+board&strSearchMin=0&strSearchMax=0&strSearchCat=0&curPage=4&sortField=price

What thickness do you recommend for the corner traps?

[CJ Paul]

I called that place last week because I was ready to pull the trigger on some panels from them.  They only ship freight and the lady quoted me $50-$60 shipping per pack depending on zip.  That is straight from the horses mouth.  That means you are really talking about $90 for 6 pieces which is not a good deal.

[Bingenito]

I purchased 8lb density wool in 2x4 sheets for .35 cents per ft in 2" thickness and .70 cents for 4" from Insulating Services in Charlotte, NC. Not a bad deal

Made a huge difference in my room. I use 2 " for wall panels and 4 inch stacked 1 sq ft in 8ft tall corner columns. No more bass issues

[bpape]

All of the mineral wool boards I saw were 8lb.

For reflection point duty, 3lb is really much more appropriate.  OC703 is the defacto standard - or 3lb acoustical cotton if you want a green product that performs better - but at a higher price.

If you're set on buying only a single product for both applications, get 703.  You can use 6" of 703 and it will outperform 4" of 705 (6lb) straddling a corner or even flat on a wall.

Also, as was stated, watch the shipping costs.  Many places blast cheap prices to come up good in price searching but kill you on shipping.  While shipping is more expensive these days and it does vary wildly from place to place, the MOST I've every had to pay to ship product to a customer in the lower 48 was $37 per box and that was in rural Washington state.  most other places are less than $25 per box.

[95bcwh]

Bingenito
   That's one heck of a deal!!!

   But 8lb, 4 inch, will it be too much even for base absorbing bass?

   damned.. why am I not living in NC..

[toobluvr]

I use........4 inch stacked 1 sq ft in 8ft tall corner columns. No more bass issues

Maybe I'm just dense, but I'm not quite following what you did here for the corner bass columns.    

BTW......great price on your panels!
Was it an online store?

[randytsuch]

All of the mineral wool boards I saw were 8lb.

For reflection point duty, 3lb is really much more appropriate.  OC703 is the defacto standard - or 3lb acoustical cotton if you want a green product that performs better - but at a higher price.

If you're set on buying only a single product for both applications, get 703.  You can use 6" of 703 and it will outperform 4" of 705 (6lb) straddling a corner or even flat on a wall.

Also, as was stated, watch the shipping costs.  Many places blast cheap pric ...

Thanks for the information.

Randy

[CJ Paul]

What evidence or measurements are there that 8lbs is too dense.  I could be totally remembering wrong but I thought Ethan Winer once recommended some 8# mineral wool from a website for DIY.

[bpape]

As I said, 8lb is great for places where you want bass control only and/or where the primary absorbtion goal is for waves hitting it pretty much each on.  The only time that it becomes an issue is when the waves are hitting it at a shallow angle - like they are for the near speaker on a side wall absorber.  

I'll try to find a study on it and post it.  It's a very difficult thing to measure as it's a very directional thing.  This has been discussed many, many times in forums where the primary goal is recording studio control rooms.  705 is also acceptable for reflection points and most finished panels available on the web are made from it as it is much easier to get it to hold it's shape.  It's a compromise but a reality.

[CJ Paul]

That's what I'm getting at.  I'm not trying to be argumentative, just want some indication.  I would honestly think that between 5# and 8# the density is not a huge difference.  Especially considering for high frequency, a lot of the absorbsion takes place at the surface only and not the entire thickness.  How much "harder" is 8# vs. 5# or 3# on the surface, etc...

[Red Dragon Audio]

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.

8/5 = 160%......therefore 8pcf is 60% more dense than 5pcf
8/3 = 267%......therefore 8pcf is 167% more dense than 3pcf
5/3 = 167%......therefore 5pcf is 67% more dense than 3pcf

I had it bassackwards.  

[95bcwh]

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 panels. I figure it will take me one good afternoon to make all of them.

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

Thanks a million!

[CJ Paul]

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 that 8# is TOO dense?  At what frequencies will it start to reflect sound where 5# would not, etc...

[toobluvr]

...............
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

Errrr...I think your math is off:

8/5 = 160%......therefore 8pcf is 60% more dense than 5pcf
8/3 = 267%......therefore 8pcf is 167% more dense than 3pcf
5/3 = 167%......therefore 5pcf is 67% more dense than 3pcf

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