whats this rigid fiberglass all about???
- Thread starter stoctony
- Start date
Ethan Winer
Acoustics Expert
Stoc,
> there is no way fiberglass would absorb any thing after the resin and everything goes on <
The fiberglass used for boats and auto fenders is more epoxy resin than glass fibers. As Earl explained, rigid fiberglass is the same as the fluffy stuff, but compressed to pack more fibers into a small space.
> i have 15X20 room. Gutted and wondering what to do with it. (acousticly) <
See the Acoustics FAQ, second in the list on my Articles page:
www.ethanwiner.com/articles.html
> A material with an NRC of 0.70 would absorb approximately 70% of the sound and reflect the remaining 30%. <
Allow me to correct two errors in the above blurb. First, NRC is pretty useless for audio purposes because it considers absorption at "speech" frequencies only. Far more useful is either the Sabins or Absorption Coefficients (they're related) when given in octave bands or, better, 1/3 octave bands.
Also, when a material absorbs 70 percent of the sound, the other 30 percent may be reflected as stated. But more likely it will pass through to the other side. This is certainly the case with rigid fiberglass panels, where mid and high frequencies are absorbed, but the lows just go right through it.
--Ethan
> there is no way fiberglass would absorb any thing after the resin and everything goes on <
The fiberglass used for boats and auto fenders is more epoxy resin than glass fibers. As Earl explained, rigid fiberglass is the same as the fluffy stuff, but compressed to pack more fibers into a small space.
> i have 15X20 room. Gutted and wondering what to do with it. (acousticly) <
See the Acoustics FAQ, second in the list on my Articles page:
www.ethanwiner.com/articles.html
> A material with an NRC of 0.70 would absorb approximately 70% of the sound and reflect the remaining 30%. <
Allow me to correct two errors in the above blurb. First, NRC is pretty useless for audio purposes because it considers absorption at "speech" frequencies only. Far more useful is either the Sabins or Absorption Coefficients (they're related) when given in octave bands or, better, 1/3 octave bands.
Also, when a material absorbs 70 percent of the sound, the other 30 percent may be reflected as stated. But more likely it will pass through to the other side. This is certainly the case with rigid fiberglass panels, where mid and high frequencies are absorbed, but the lows just go right through it.
--Ethan
TexRoadkill
Audio Bum
stoctony said:
FYI- The stuff with the foil backing is usually 705 and without the foil it is 703. 705 is more dense and better for bass absorption and 703 is better for absorbing the highs.
Thank you all for the great advice. You have been a great help. I havnt heard the stuff in my room myself but from you guys it sounds like this stuff really is the Holy Grail. This question may negate the whole great post I have going but here it is anyway. Why cant I just line all of my walls with S/R/F and call it good. I swear, I have been listening to you all. Just a question to try to simplify things for me. Thanks in advance
Stockton
Stockton
TexRoadkill
Audio Bum
stoctony said:
Too bad it's not quite that simple. Every room is going to have a different type of frequency response. Usually you are going to have to tame the low end in a small room and try to kill some of the direct reflections that can really color your tracks. In a big room you may want to try and reduce the overall reverb time.
When you apply sound treatment you want to do it with a goal in mind. If your room needs to have the lows reduced and instead you dampen all the highs then the room will be very dead in the high end and very boomy in the low end. You have actually made the problem twice as bad. If instead you treat the low end and leave the high end untouched or just diffused you might actually balance out the response of the two.
The ultimate goal is to have a room that is very balanced sounding. Determine what the problem is and apply the correct solution.
S
SpokenWord
Guest
Fitz:
I am a new subscriber....great forum. Do you have any thoughts on Sonex made by Illbruck ? (Link- http://www.illbruck-sonex.com/sBroad_main.html) I want to build my own Foley Studio at home. Sonex is pretty expense, but seems to be worth the investment....as you know, with Foley, the sounds have to be completely isolated ....what do you think?
SpokenWord
I am a new subscriber....great forum. Do you have any thoughts on Sonex made by Illbruck ? (Link- http://www.illbruck-sonex.com/sBroad_main.html) I want to build my own Foley Studio at home. Sonex is pretty expense, but seems to be worth the investment....as you know, with Foley, the sounds have to be completely isolated ....what do you think?
SpokenWord
RICK FITZPATRICK
New member
Hello Spokenword, and welcome to the board. Sonex huh. Well, let me clarify something first. I am by no means a guru on this board. Just a little more enlightened than your average Homerecording enthusiast. But I do have an opinion although foley is out of my area of expertise. Hell, I'm just CAD draftsman with a home studio, although I've read a lot.
As to my opinion, Sonex is the industry standard for architectural looks as it is listed in Architectural specification catalogs such as Sweets. High dollar environments such as broadcast, film and TV studios which are designed by Architectural firms who are not really acoustically oriented, often have products such as Sonex specified, which may not be the best for music recording studios, but are fully within the acousical performance criteria needed and are also "architecturally" attractive.
You are right though, as it is very expensive, compared to other products, such as Owens Corning 700 series rigid fiberglass products, which perform much better, at a much cheaper price point. However, you may not need a broader band of absorption, as you are not recording music or vocals, or even dialog for that matter.
So offering an opinion on other products use in a Foley room would not be appropriate though, as I have no idea what you are recording, although I suspect it is overdubbing live sound effects while you preview the film. Is that correct? I would also suspect it must be done in a highly isolated environment, with the ability to alter the RT-60 of the room, but that is just a guess. Maybe you need a totally dead environment and artificial ambiance is added or mixed with the live film audio track at edit time. As you can see, it would be pure conjecture on my part. But I see it used all the time in environments other than music recording studios, and even in some of those too, such as isolation booths although I wouldn't have personally used it.
But if it WERE up to me
I would specify fabric covered 703 rigid fiberglass panels of varied thickness and size, some with large louvered panels for altering the absorption which also will contribute to diffusion if designed correctly, and Slat absorbers for low Hz absorption if needed. Of course, I'm a cheap skate,
so what can I say.
fitZ
As to my opinion, Sonex is the industry standard for architectural looks as it is listed in Architectural specification catalogs such as Sweets. High dollar environments such as broadcast, film and TV studios which are designed by Architectural firms who are not really acoustically oriented, often have products such as Sonex specified, which may not be the best for music recording studios, but are fully within the acousical performance criteria needed and are also "architecturally" attractive.
You are right though, as it is very expensive, compared to other products, such as Owens Corning 700 series rigid fiberglass products, which perform much better, at a much cheaper price point. However, you may not need a broader band of absorption, as you are not recording music or vocals, or even dialog for that matter.
So offering an opinion on other products use in a Foley room would not be appropriate though, as I have no idea what you are recording, although I suspect it is overdubbing live sound effects while you preview the film. Is that correct? I would also suspect it must be done in a highly isolated environment, with the ability to alter the RT-60 of the room, but that is just a guess. Maybe you need a totally dead environment and artificial ambiance is added or mixed with the live film audio track at edit time. As you can see, it would be pure conjecture on my part. But I see it used all the time in environments other than music recording studios, and even in some of those too, such as isolation booths although I wouldn't have personally used it.
But if it WERE up to me
I would specify fabric covered 703 rigid fiberglass panels of varied thickness and size, some with large louvered panels for altering the absorption which also will contribute to diffusion if designed correctly, and Slat absorbers for low Hz absorption if needed. Of course, I'm a cheap skate, so what can I say. fitZ