That is a good question. If you do a comparison of the Owens Corning 703 boards vs. the Roxul Safe-n-Sound vs standard mineral wool you can see some things.
Originally Posted by jbrown15
You would need to compare the Sound Absorption Coeffiecnts of each of the products for a direct comparison. Since in a DIY project it would be impossible to find the Coeffiecents of that specific build we can then only use the test data we have avaiable. Since most data does not go beyond 4" thickness we would need to compare the 4" thickness numbers. Also, we need to make sure that the test data are considered equal. In this case we would need to make sure that we verify that the product is all tested in a Type A mounting (meaning flat on a solid backing surface).
Just looking at the 125 and 250 Sound Absorption Coefficents we can see what product performs the best at the given thickness.
703 - 125hz = .17 250hz = .86 (2" max given)
Safe - 125h = .52 250Hz = .96 (3" thickness only given)
Wool - 125h = .35 250Hz = .65 (3" thickness)
Wool - 125h = .45 250Hz = .90 (4"thickness)
Based on that little bit of information it would seem that the Safe-n-Sound would perform better then the others. However, that only shows absorption down to 125Hz. With products such as this the numbers drop off very quickly below 125Hz. This is due to the fact that most porous materials are laid out in layers. For this reason the acoustic properties vary depending on if the sound incident is parallel or perpendicular to the fibers making up the porous material and that porous material in these thicknesses can not absorb the energy levels suffcicent to reduce LF.
For fun here are numbers from a standard 3" and 4" thick absorber panel not specifcally a bass trap.
RPG 3" Absorber Panel - 125Hz = .56 250Hz = 1.09
RPG 4" Absorber Panel - 125Hz = .76 250Hz = 1.12
Due to the limited ability to test LF panels in labs it becomes tricky to get good absorption numbers for products in the lower regions (below 125Hz) but here are some good products from a well respected manufacture company that we utilize all of the time.
RPG "Modex Braodband" 4" thick -
63Hz = .50 100Hz = 1.00 160Hz = .82 250Hz = 1.01
RPG also has another product called "Modex Edge" that looks great. A stackable bass trap that can be for the corner or on a flat wall. It comes ready to place and can be stacked. Therefore, a easy way to tune the LF in a room with pre-made bass traps.
And hopefully I answered the question...
Den: Parasound A21, Parasound P7, Cambridge Audio 851C, Cambridge Audio iD100, PBS Synchrony-One, Tannoy DC6TSE, Tannoy TS2.10
Gun/Wine Cellar: AR Rotel RX820, Cambridge Audio iD100, Tannoy Di6DC