Superchunks with Loose Fill Rockwool

Sebg · 9th December 2010

I did a search and didn't find this anywhere else so sorry if it has already been posted.

A corner bass trap absorber is basically a triangular prism of 430Litres volume (600x600x2400mm). It seems to me to be a lot of work cutting all those batts more or less accurately into triangles and getting Glasswool or Rockwool fibres all over the place. My proposal would be to:

a. Make a timber frame into the correct shape, perhaps slightly more than 90degrees at the apex and slightly less than 600mm at the sides, just to fit more neatly into room corners that are not quite square. The apex should also be cut off slightly as well to ensure that the absorber can be pushed all the way into the corner.
b. Wrap the frame with insect screen (the tough variety) or 80% knitted shadecloth pulled taut or something to hold the fill in.
c. Wrap with chosen decorative, mostly acoustically transparent fabric. (bass absorbers are not so fussy about acoustic transparency compared to mid and high-freq absorbers).
d. Fill with granulated Rockwool (should be less dust and fibres floating around than in the case of cutting high-density batts). Conceivably, loose fill cotton waste, polyurethane foam waste and other materials would work as well.

Once installed, it might still need architraves at the wall edge for decoration. Making the frame I suppose may not be that much less work than cutting all those batts. The loose fill may also settle a bit over time but a horizontal divider or two would help reduce the total weight supported by the fill at the bottom and it can always be topped up - it will stop settling eventually.

Bags of granulated Rockwool around here (Sydney, Australia) are $40 for a bag of 12.5kg that is nominally 57kg/m^3 density. So just about two bags ($80) would be needed for one "Superchunk". This compares to $220 for 8.6m^2 of 50mm thick 32kg/m^3 Glasswool to fill the same volume. (100mm 32kg Glasswool is more than twice as expensive as 50mm. 32kg/m^3 Polyester batts are around $22/m^2 for 100mm thickness but are a pain to cut).

_Ludovico · 3rd January 2012

The insect screen idea is great! thanks for the tip

9th December 2010	#1
Sebg Gear addict Joined: Oct 2010 Posts: 389 Thread Starter	Superchunks with Loose Fill Rockwool I did a search and didn't find this anywhere else so sorry if it has already been posted. A corner bass trap absorber is basically a triangular prism of 430Litres volume (600x600x2400mm). It seems to me to be a lot of work cutting all those batts more or less accurately into triangles and getting Glasswool or Rockwool fibres all over the place. My proposal would be to: a. Make a timber frame into the correct shape, perhaps slightly more than 90degrees at the apex and slightly less than 600mm at the sides, just to fit more neatly into room corners that are not quite square. The apex should also be cut off slightly as well to ensure that the absorber can be pushed all the way into the corner. b. Wrap the frame with insect screen (the tough variety) or 80% knitted shadecloth pulled taut or something to hold the fill in. c. Wrap with chosen decorative, mostly acoustically transparent fabric. (bass absorbers are not so fussy about acoustic transparency compared to mid and high-freq absorbers). d. Fill with granulated Rockwool (should be less dust and fibres floating around than in the case of cutting high-density batts). Conceivably, loose fill cotton waste, polyurethane foam waste and other materials would work as well. Once installed, it might still need architraves at the wall edge for decoration. Making the frame I suppose may not be that much less work than cutting all those batts. The loose fill may also settle a bit over time but a horizontal divider or two would help reduce the total weight supported by the fill at the bottom and it can always be topped up - it will stop settling eventually. Bags of granulated Rockwool around here (Sydney, Australia) are $40 for a bag of 12.5kg that is nominally 57kg/m^3 density. So just about two bags ($80) would be needed for one "Superchunk". This compares to $220 for 8.6m^2 of 50mm thick 32kg/m^3 Glasswool to fill the same volume. (100mm 32kg Glasswool is more than twice as expensive as 50mm. 32kg/m^3 Polyester batts are around $22/m^2 for 100mm thickness but are a pain to cut).

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3rd January 2012	#2
_Ludovico Lives for gear Joined: Nov 2009 Posts: 891	The insect screen idea is great! thanks for the tip