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I'm planning to make some absorption panels which have high WAF ...*Three 2.5'x4'x3" boxes spaced across a 9' wall
*the wavy "over the veranda" fiberglass panels as backing
*2" of fiberglass insulation
*topped off by pillow bunting to prevent fiber escaping
*covered and prettified with a silk scarf, stretched over the frame
*each box held out from the wall about 1.5" or more
Questions: Does this sound feasible in general? And will silk work as the first layer, allowing sound in to the box (or does it have some reflective quality?)
Thanks!
Follow Ups:
And two more questions: What about wool rugs? Wool wall tapestries?Cheers!
Wool rugs are typically going to be too dense to do much good in the HF's and midrange, and not be thick enough to absorb much bass, while the tapestries are even worse, denser and thinner.As for cashmere, this is still mostly wool, and from what I have seen, the density is still on the high side.
Realize thyat most of these types of fabrics that look fuzzy or velvety are woven very tighyt/dense on the rear, and just about the only sound absorption will come from the very thin layer of "fuzz" on the front surface, the midrange and most of the highs will reflect off of it by say 70-80%, and waste the sound absorbing material behind it.
If you want a "nice" looking fabric, and are willing to pay fo it, check out the Rolls-Royce and Cadillac of acoustic fabrics:
Guilford of Maine - FR701
http://www.silentsource.com/acousticore-colorchart1.html
goto
http://samplecenter.guilfordofmaine.com/servlet/Search
and select "FR 701® - 2100"
under the 'Browse Products' Search functionand
Acoustone Cloth (for speaker grilles)
http://www.acoustonegrillecloth.com/These are considerd to be the premium acoustical fabrics for interior use, fire-retardant to UL standards in most cases, absolutely uniform and consistent, with color fast shades.
However, I know of none of their offerings that are as sheer and smooth as silk, your best bet is still some double-knit ployester speaker grille cloth (not just any old double-knit or polyester, it needs to be rated for speaker grile use, and preferably obtained from a suitable source such as Parts Express or a speaker supply companies/vendors).
The main criteria is that the fabric either allow the sound to pass through unimpeded, so the sound absorbing material inside the cloth can do it's job, OR that the cloth be absorbent enough in the highs and midrange, and alow the bass to pass through to the sound absorbing material behind. Speaker grille cloth and most of the offerings of the above two mentioned firms fall into the first category, while burlap and other corse weaves fall into the seccond category.
Both Guileford and Acoustone offer samples and sample books, so you can send for them to let your wife see what they are like.
Thanks, Jon. Perhaps the wife will approve of three panels of different colors, each tying in to the existing color scheme. If not, I will now avoid rugs, tapestries, and other tightly woven but look for something that fits your description of suitability. I appreciate your taking the time to help me. ~Tom
"*covered and prettified with a silk scarf, stretched over the frame"Why not come up with a way to have these coverings over your panels when critical listening isn't going on. This could increase your WAF enough to change her "How can I get rid of these" to "Gee, that's pretty".
Thanks, Rickey! This is a great option.
Thanks so much for your advice, all!One further question: The wife heard "no silk" and would like to know about cashmere... Anyone?
Thanks again,
Silk is not good at absorbing or letting through HF's, so too much will reflect off of the silk.The most similar thing I can think of is speaker grille cloth, almost everything else is a lot rougher and/or corse.
One other thing, placing a hard backing on the rear is going to LIMIT LF and midbass absorption, and the spacing off the wall will be wasted and inefective due to the hard fiberglass surface. If you need a substrate to work against, perfboard with as many holes as possible, chicken wire, or build an open frame with cross members, then 'seal' the rear with a layer of polyester batting.
Jon Risch
I had similar home-decor demands when I made some panels, so used some open-weave "ethnic" fabric as the external covering. You may be able to find a variety of such material at places like Pier One or similar shops. The important thing is that the weave is very loose or open - hold it up to the light or try to breathe through itBy the way, if you leave the back of the panels open to the fiberglass/poly rather than covering it with something rigid, you'll get better absorption when they are spaced off the walls
The best way to tell is to talk to the fabric while walking up to it. Listen for timbre changes in the reflected sound of your voice.
Thank you for these thoughts! Now, I imagine I would get some REALLY odd stares if I walk into Safeway and start speaking to the product in the feminine hygiene aisles...!
Tom,> will silk work as the first layer <
No, silk is not good because it's too reflective at higher frequencies. It would be fine for bass traps though. For mid/high frequency absorbers you want soft fabric you can breath through easily, like burlap or muslin.
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