To be as effective as fiberglass you'll probably need a lot of fabric which would increase cost?
What fabric properties would one want to look for when choosing drapes for absorption?
How to calculate the optimal depth of a pleated drape?
Would absorption benefit from hanging multiple layers at different wall distances instead of hanging one single pleated drape?
Best, Markus
Of course - the fabric can easily get to be much more expensive than fiberglass, I usually look for deals. The velour knid of heavy thick weave that is not very tight is best. To optimize pleat size and fabric density etc. you would have to go to Ingards book. Multiple layers is also dealt with in the book - there is a section on "multi-layer" absorbers. Orignially the bookk came with software to to the calculations, but the soiftware is now obsolete and the code was never available. A windows program that did the same things would be very cool.
Oh yea, about the Antonio book, I'm not a big fan. They present the ideas as best promotes their products. There are lots of ways of doing the same things without the excessive costs of their products. Like the stone walls that I use in most of my rooms. They are not going to tell you about that and how its just as effective, lots cheaper and far better looking than what they sell.
I'm not like some people here that tend to believe everything they read and then feel betrayed when they find out that there's more to the story than they were told 😉
From what I could read at Amazon, the book seems to be a good overview of acoustic treatments presented with a solid theoretical background.
You recommend using fiberglass inside you living room?! 😱
It's a free ticket to the asthma clinic
You recommend using fiberglass inside you living room?! 😱
It's a free ticket to the asthma clinic
I don't get this! and I hear it often.
So, it turns out f/glass is 'radioactive', for some reason unknown to science the f/g particles have a 'half life' and decide to defy the second law of thermodynamics and just eject themselves from the surface at random!!
There they are, left alone and untouched, and the particles are exploding off the surface spontaneously.
Don't buy it myself. Cutting f/glass is of course a different story, but even then they stop dispersing into the air once you stop cutting.
Wrapping f/glass then it is even more crazy to suggest asthma etc (esp one would use compressed f/glass, if only to make the job easier for themselves) cause now not only do they spontaneously eject from the surface, they undergo 'quantum tunneling' and burrow thru the material.
Anyone is free to worry about things they want to worry about, and god knows I tend to worry about different things than most people into audio, but the health risks of f/glass is not one of the things I personally would worry about, YYMV.
Tho sometimes I sit there eating my hamburger, drinking my beer and smoking the cigarette and look at the f/glass thinking to myself 'that is so unhealthy you really should do something about it' haha.
No, they dont eject themselves or are radioactive. 🙂
They have a half live in terms of biodegradability, which means the stuff you get into your lungs wont sit there forever, but can be dissolved by your body - at least the newer rock wool has to have this attribute.
They have a half live in terms of biodegradability, which means the stuff you get into your lungs wont sit there forever, but can be dissolved by your body - at least the newer rock wool has to have this attribute.
Fiberglass has been proven to not be carcinogenic, but it is know to be highly alergenic to many people. If undisturbed for a long time this is not an issue. Put putting it in AND taking it out is a real issue for many people - myself included. And it doesn't take much to "disturb it" to the point where it is irritating. It can be a big problem for people with asthma - getting to be about 1/2 the population from what I understand.
There are also "green" alternatives to fiberglass with very similar properties made from wood fibers, polyester, cotton, etc.
This stuff for example: Thermo-Hemp i got a sample once and it feels nice, very similar to rock wool, but without the fine fibers that itch so much. And no evil stench of glues or solvents at all.
Btw... the carcinogetic qualities of rock wool are dependant on the fibers diameter, shape, length and biodegradability. Splinters of about 3 micrometers diameter, about 30-50 in length and a needle like shape do cause cancer. Its only not carcinogetic any more (in europe), since the carcinogetic ones were banned from the market in 1995.
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It's not so much about how you call it but about knowing a material's properties. Porous absorbers are easily calculated. For fabric I don't know any data or calculations.
can You tell us please how exactly your multi-way omni-dipole setup looks alike?
It seems to be completely different from single driver closed box that I have built. I wonder what can be the operating principle common to them.
best,
graaf
Markus, This might be of interest. There is a software program which is freeware.
Sound Absorption in Free Hanging Textiles
http://www.ognedal.com/software/abs...Sound Absorption in free hanging textiles.pdf
Sound Absorption in Free Hanging Textiles
http://www.ognedal.com/software/abs...Sound Absorption in free hanging textiles.pdf
Except that fabric is generally either woven or knitted. This stuff is loose fibers. As to whether that makes a difference, I don't know.
Felt is an unwoven fabric, and is often used for acoustic damping/absorption.
I don't think that the difference is significant - weave and tighness is a factor, but thickness and density are the bigger ones.
That was a decent paper - thanks Frank. Lots of good info that I have not seen before.
That was a decent paper - thanks Frank. Lots of good info that I have not seen before.
Dr. Geddes, why don't you absorb the ceiling reflections? Do you listen in the room that has the high ceilings you've mentioned else where?
Thanks,
Dan
Thanks,
Dan
I use a custom designed diffuser on the ceiling. It is specifically design to reflect the signal back towards the front of the room where there is lots of absorption. This technique works better in a limited size than an absorber, and its one way. It is reflective from one direction and difussive from the other. I have quite a limited ceiling height in my room so any absorber would have had to be thin and not so effective.