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Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

Re: questions for BDIAMENT

Hi jwitzsch,

I'd be happy to answer what I can in this post. In order to send specs for Hip Joints, I'd need an email address so I can attach them.

1. Bass Trap fabric: I used a 100% polyester knit. The source was
http://www.fabricdirect.com/acatalog/Online_Catalog_Interlock_Knit_4220.html
The material is quite transparent sonically and feels a lot like a very, very thin felt.
A good loudspeaker fabric should work fine.

2. Bass Trap foil/paper: I'm not sure why you believe I "obviously do strip the whole aluminum cover-foil from the tubes" but this is not the case. The fiberglass pipe coverings we used, made by Knaupf, come with a foil/paper cover. I just cut away this cover from 1/2 of the cylinder, lengthwise, leaving the other half to serve as the reflective/diffusive surface. I did not use the plastic, painter's "dropcloth" that some folks use. The foil/paper sounded fine upon audition and has worked out quite well in the listening room.

I personally wouldn't go with the "stripes" of foil since you'd have compromised absorbtion, with the stripes getting in the way and compromised reflection/diffusion because the stripes don't cover enough surface. Leaving half the cylinder (lengthwise) covered and half uncovered lets you change the sound by rotating the trap. This is simple, effective and easier to build as well.

3. Trap stability: The 16" (i.e. 400mm) traps are quite stable. The 9" (i.e.225mm) on the other hand can get tipsy, especially when two are stacked into a column. You have to be careful to trim away excess fabric from the ends. I have also added an additional circle made of 1/4" birch to the ends and middles of my columns (2 traps). The additional circle adds stability and looks quite attractive as well. Bottom line for the narrower traps is some care is definitely necessary unless you choose to anchor them somehow, perhaps with a string at the top and/or an adjunct "base" at the bottom.

4. Enjoyyourshelf racks and Hip Joints: Below are some links to my main posts about these. I hope you find them interesting. With your email address, I can send the specs for Hip Joints and you can make some (or have some made) for your personal use. The last link below, "Econo Isolation" will show you how to make simple versions for very little expense.

Roller bearing isolators: some thoughts and observations
http://www.audioasylum.com/audio/tweaks/messages/42825.html

Roller bearing isolators: thoughts and observations pt.2 (the shootout)
http://www.audioasylum.com/audio/tweaks/messages/43275.html

Finally... the "Enjoyyourshelf" racks
http://www.audioasylum.com/audio/tweaks/messages/62128.html

The Enjoyyourshelf racks: further thoughts
http://www.audioasylum.com/audio/tweaks/messages/63073.html

Seismic Isolation for Loudspeakers (Bound and Gagged No More!)
http://www.audioasylum.com/audio/tweaks/messages/74038.html

Econo Isolation
http://www.audioasylum.com/audio/tweaks/messages/77185.html

Happy Listening!
Barry


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