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Well, I have finally done it. Here is *the* DIY cylindrical bass absorber project I have been threatening for quite a while. It is actually very simple to make, and very cost effective as you will find out. Forget about any other bass absorber project you have seen. This is the one. Made of the very same materials as the ""name" brand absorber, for pennies on the dollar. I hope you enjoy this as much as I have. Comments are always welcome!
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Tools needed-
You will locate the tube material at any industrial heating and cooling outlet. There are three or four brands, but the tube is used as the insulation cover of heating and cooling pipes. The brand I found in my area is Knauf fiberglass pipe The tube comes wrapped in an aluminum/paper backed wrap. This layer will become the reflective wrap of the absorber. DO NOT REMOVE YET!
The tube is split on one side so as to put around pipes. Prop the tube open and run a nice thick bead of adhesive (Liquid Nails etc.) along the vertical edge. The paper covering has a peel back adhesive paper lip that holds the tube closed while it dries. Run a bead around the top. These beads MUST be gap free. The tube MUST be air tight for it to be effective. Place the drywall circle on the top with a slight turning motion to ensure the adhesive is gap free. Repeat on the bottom. Place a couple of books on it overnight to cure. Above and right I have dismantled one for show.You can see the glued on drywall with half of the tube covered in the supplied paper. The side with the paper showing is the front, for diffusion. The side showing the raw tube is the absorbent side. Here also you can see the rear of the fabric just folded over and pinned. As it faces the corner, it will never be seen. I needed to match the fabric to the traps that I already owned, so I tracked down Guilford. They can be reached at- Guilford of Maine The Crème color ASC uses is called Quartz, FR 701, Style 2100, #380. You can order it custom cut for a couple bucks more. Don't get caught up in finding a fabric that you think has to "breath" like open weave burlap. (Ugly!) Bass does not travel in waves, it behaves as pressure. (If bass can go right through a flimsy wall, it will certainly go through a piece of fabric!) When the trap is dry, cut half of the diameter paper off. I cut off the side away from the seam. Now one side is reflective, the other, absorptive.
Cut the fabric so it overlaps the ends of the tube about three inches each end. Wrap the fabric around the trap and pin down the seam. Don't worry about getting it super tight now, you will get it tight when you staple the top and bottom. Fold the fabric over top and put a couple of staples to hold it. Directly in line from that, pull the bottom tight and staple. Work your way around, alternating top and bottom. Make sure you decide which way you want facing outward before you wrap it. IE- the side that faces the wall will have the seam, unless you care to sew the seam. (Good luck!) I stopped at this point. If anyone takes this a step further, please drop me a note with the details. Have fun! Here is the latest price list I have. |
covering. They come in assorted sizes, just remember that the specified size is the INSIDE dia. of the tube. IE- A 10 in. tube wraps around a 10 in. pipe. With the 1" thickness of the tube, the outside diameter would be 12". The tube is compressed fiberglass, and is 1 in. thick. They come stock in 3 ft. lengths. A rough rule of thumb is 10-in. tube will absorb down to about 70 Hz. 20 in. tube to around 40 Hz.
From a small sheet of 3/8-in. drywall, cut circles the same size as the outside diameter of the tube. These are the top and bottoms. You can use wood, but drywall is easier to work with. All you need is a surface to glue on and that will hold staples.
