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SurfCables: Silver Teflon Audio Cables

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PartTimeProjects Tube Bass Traps

As stated on my hanging bass trap page, bass traps are commonly used to treat the acoustics of a room. You will find them in studios and movie theaters where they control echos and tame boomy bass to make it tighter and more precise. They "absorb" the bass, rather than reflect or redistribute it. Bass traps are commercially available or you can make your own.

Unlike a hanging bass trap (pillow of fiberglass), a tubular bass trap is a cylinder of fiberglass optionally wrapped in "batting" wrapped in a loose weave fabric. A round "tube trap" is preformed or user-compressed fiberglass in a sealed tube that is usually placed in the corner of a room. You can compress 6" or 4" wall or ceiling fiberglass or use prefabricated pipe insulation (called "preformed" pipe insulation).

Here I used some mineral fiber pipe insulation, 8" inner diameter and 2" thick mineral wool. I covered this in batting and then in fabric. I used a layer of plastic to reflect the high frequencies on about 1/2 of the surface area.

Here are some links showing the concept of these bass traps-

Attention! These tube traps are made out of preformed mineral wool insulation. One audio 'bass trap' guru (John Rish) has said that this type of insulation provides inferior bass absorbtion compared to simply rolling up and compressing standard fiberglass insulation around a circular frame and covering this with cloth (described at --geocities link no longer valid!--). See this link for the critique:

Hmmm....wish I saw that before I bought the pipe insulation! Looks like there is a dispute as to how good these are. Mine are improved by having a 1.5" batting covering the insulation, but I have not yet done measurements to see how effective they are. They do absorb bass, that is easy to tell from listening with them in position and removed from the room. It does sound better with them in place.

Here are the steps I took to make them.

Step 1: Making and Sealing The Tube

Gluing sides of insulation together.
Adding 1.5" batting to the insulation.
Adding plastic for HF Reflection.
Adding wood sealers.

Notes: You see here that the halves of the mineral fiber tube are glued together with an adhesive such as "liquid nails." Batting is glued on, I used 1.5" thick poly batting, wrapped with string to get it on there securely....like a roast! Then you put a high frequency reflective plastic layer on top of some of the batting, to orient the trap for partial HF reflection. This is glued with the adhesive as well. I then sealed the tube by gluing in circular cutouts and sealing with silicone sealant. I then covered the ends with clear plastic so the mineral fibers would not get out.

Step 2: Finishing

Adding outer supports.
Adding fabric.
Tigenting up the fabric

Notes: Here I have added a circular wood base to the bottom and top, with a "pillow" of batting on top of the tube since I will not be stacking the tubes. I have added some fabric around the tubes, I chose a linen which is why it is so wrinkled, I've got to steam it! Hey, the 2nd pic looks like "Lawrence of Arabia!" In the third pic you see the trap that just needs to have the fabric tightened a little bit. The front is a little darker as the black plastic is slighlty visible beneath the linen fabric. I like the linen, it is a very nice loose weave just as loose as burlap but softer and looks much better.

Done, In-Room Pics

Round Trap & Hanging Trap

Hey look! You see the finished tube trap with a hanging bass trap over it.

Well, there you have it, some tubular bass traps. Not officially approved by everyone but hey, they do actually work and that is OK with me.