Home Studio DIY Acoustic Treatment – Part 3
We now need to work on the Super Chunks.
These fix into the 2 main corners of the room, directly in front and side of the bay area. These will be made from the damn Rockwool. The Chunks will be fixed from floor to ceiling and covering the whole corner areas.
As we bought exactly enough materials for this job, it is important to note that because Rockwool is not available in 1 metre x 1 metre dimensions in the UK anymore, we had to use some clever geometry, or rather Max did, to get the full-length Rockwool to be cut from 1 metre x 60 cm dimensions. This meant that we either had to lose the excess Rockwool from the corner shape cuts, or we had to use them. We chose to use them. So here is a diagram on how to cut the Rockwool slabs to make the triangular corner Chunks.
As the diagram shows, you have a Rockwool slab that is 1 metre in length and 60 cm in width. By measuring in 60 cm into the length, you will have a 60 cm x 60 cm square. You then need to cut diagonally, from corner to corner, to form 2 triangular shaped Chunks.
The leftover is the segment at the bottom, 40 cm x 60 cm.
Measure 40 cm into the width and 20 cm into the length (Spare). Now cut diagonally across this measurement (green line). What you will be left with are C2 and C1. Place C2 on top of C1 and voila you have another triangular Chunk (picture below).
The Super Chunks should now measure 60 cm x 60 cm.
The next step is to build the damn wardrobe corner Chunk.
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| Place the Rockwool Super Chunks into the corner of the wardrobe, making sure you have polythene placed under the polythene sheet. As we will be spraying the Chunks with PVA, we need to protect the carpet from the adhesive, thus the polythene sheet. This can then be removed. | Place the Chunks into the different layers of the wardrobe and tight into the corners. |
| Spray the Rockwool with the PVA solution we made up, making sure to cover the entire surface area. This is to prevent the Rockwool from breaking up and getting airborne. Once dry, remove the polythene sheet from under the Chunks. | |
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| As you can see the Chunks are now being covered in fabric. Apart from aesthetic reasons, the fabric holds the Rockwool in place and prevents it from breaking down and sagging. We used the spare 2” battens from our earlier frame building project and screwed these onto the frame of the wardrobe to hold the fabric in place. You will probably need 2 of you to do this properly. | This is one complete corner Super Chunk. This procedure must be repeated directly on the other side of the room, on the opposing corner. This makes for a matched and symmetrical shape. |
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| This is the exact same principle applied to the left-hand side of the room. Floor to ceiling Super Chunk, made from Rockwool, and battened in and covered with fabric. | As the wardrobe was still resonant, we created 2 more panels, made from the Rockwool, and placed them against the walls of the wardrobe. So, we now had one mutha corner Super Chunk and 2 more bass panels. The picture clearly shows that the 2 panels are placed adjacent to each other on both the wardrobe walls. This provides further absorption. |
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We now need to go back to the panels we built, that we fixed onto the MDF panels, and use these as suspended diffusion and absorption panels. This involved drilling holes into the ceiling and using eye screws.
We then measured and cut funky chains to about 8″ and used these to suspend the panels from the ceiling. As we used 2 ply, we had to use small and thin screws so as not to damage the 2 ply and foam.
These panels were placed directly above the listening position in the room and in-between the wardrobe and left walls.
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| As you can see the suspended panel is placed just in front of the bay area, where I sit, and in-between the two perimeters of the bay area. | These are the doubled foam panels we built earlier and the vented MDF panels provide good absorption and diffusion. |
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Of course, you need two to complete the build. These are placed equidistant from each other and from the side walls.
We now need to add the final Procorner foam to the left hand
side perimeter of the bay area.
This is the far left-hand side of the bay area and you can see the suspended panel and the Procorner foam sitting just behind it.
The foam is joined onto the last corner foam on the edge of the bay area that we fixed earlier.
You can also see the left hand Corner Super Chunk in the background.
Corner Chunk, left-hand perimeter and bay area edging, and the left-hand side suspended panel.
This is the final panel that is fixed onto the ceiling on the left-hand side of the room. It is the mirror image of the wardrobe foam.
Symmetry is crucial for a balanced stereo image, so we have duplicated left and right to maintain this balance. Acoustic treatment is not only about proper frequency referencing but about a balanced and true stereo image. This now leaves us with all the bass panels we built and also some more absorption panels that we built later for the walls etc.
The bass panels have been covered earlier in this tutorial, so I am not going to go into how to build them. However, absorption panels are crucial. These are easy to build. It’s simply a case of Rockwool placed onto some 2 ply boards and sprayed and sealed in with the fabric. The trick with these panels is that when it comes to fixing them onto the walls, air gaps must be left behind so as to provide better absorption and some diffusion.
This was achieved by using the small circular wood cutouts we had left after we drilled the holes into the battens when making the panel frames. These are little round wooden circular bits that look like thick coasters.
Simply glue 5 of them on the back of the 2 ply board (one in the middle and 4 on the corners) and then fix this onto the wall. This keeps the 2 ply away from the wall and thus provides better absorption and diffusion. However, you may have a better way of doing this, so experiment.
We then placed these absorption panels on all the walls.
The following pictures end the story.
All wall panels in place, all corner bass traps in place, all absorption and diffusion panels in place, all chunks in place etc..
Well, that’s pretty much it. I hope that this helps in making you aware as to the fact that, with a little money and some simple hard graft, you can build a nice acoustic environment to work in.
I would like to take this opportunity in thanking Max the Marvel for all his selfless help and direction and for blocking out half the sunlight in the Bucks area.
I would also like to take this opportunity in thanking my local hospital for separating my fingers and eyelids after…ahem….a little adhesive incident.
Take care.
Zukan (Eddie Bazil)
