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In Reply to: Re: Polyester batting substitute posted by Jon Risch on June 16, 2004 at 22:02:34:
Hi There,Thanks again for all the info.
I will use the Soundlite product as seen here: Soundlite. I plan, as per your information, to use a 25mm (~1") board of 80kg/m3 followed by a 50mm (~2") 40kg/m3 board. I will then cover that with batting (~1") and then the entire panel with burlap. Is there any other details I need to be aware of, such as specific methods to glue the panels together, or whether to get them lined with paper/foil or not? If memory serves me correct from previous threads, I believe they should be unlined boards, except the first one, which can have one side (the side which will be against the wall) lined. Is standard carpet adhesive okay to bond the board together?
As for the bass traps: my two options are your SQ&D traps, and the ones by Jon Gale using fiberglass pipe covering.
For your SQ&D traps, what density do you recommend? I have a number of options, as seen here: Fiberglass options and thus I can get a density of anywhere from 12kg/m3 (fiberglass) to 160kg/m3 (rockwool). In either case I will get a roll which comes to around 16" diameter as you suggest. The ones here don't come with plastic covering so I will wrap them in a thing layer of batting (to keep the fiberglass in) and then burlap (aesthetics).
If using Jon Gale's design though, I can get pipes only of around 80kg/m3 and of 160kg/m3. Which would you recommend. I will most likely try both designs to see what works best in my room.
Thanks again and have a good day,
X
Follow Ups:
RE 1st batch of Q's: Yes, you have the layering correct, but make sure the higher density board is toward the wall. As for the panel lining, none is best, or the pin perforated second best.As for gluing fiberglass together, I am not sure if carpet glue will work, I have had reports of folks using 3M "77" spray adhesive to good effect, the secrect with this kind of adhesive, is to use per directions, using plenty, and letting it partially dry before bonding the fiberglass to a surface.
BTW, I would not glue them to the wall, leave an air space if possible, they will work down to a lower frequency, and provide a more natural balance in the room.
RE 2nd batch of Q's:
The Super Quick & Dirty traps are very non-crtical of density, as long as it is within a certain range. 40 to 80 kg/m3 should do the job quite well.As for the Gale traps, see:
The problems with steam pipe insulation for bass traps:
http://www.AudioAsylum.com/audio/tweaks/messages/57035.htmlhttp://www.AudioAsylum.com/audio/tweaks/messages/6425.html
AND
http://www.AudioAsylum.com/audio/tweaks/messages/13535.html
AND
http://www.AudioAsylum.com/audio/tweaks/messages/3771.htmlIn essence, the density is too high on the steam pipe insulation, and the preformed insulation apparently has to little porosity (too much binder?), for maximum performance. With the pressure mode operation type bass trap (which is the principle behind the Gale traps, as well as my DIY traps, and of course, the orginal retail product from ASC), the main thing is not so much density as it is porosity, the layer of fiberglass provides a pressure flow resistance, and this can be acheived more ideally by compressing material that is not full of binder.
Jon Risch
Hi There,Thanks again for the great info. I will do as you suggest with the dense layer toward the wall, followed by the less dense board then batting then burlap. I will also ask the fiberglass guys here about adhesive glues to use (it will most likely not have the same name here so if I ask for 3M '77' I will get some very strange looks :)
I only plan glueing the boards together so no worries there. I will try make these portable so that I can put them up, take them down, move them around etc. I may mount these panels on PVC pipes as I saw in the pictures of the wall panels on your site - that kills two birds with one stone (provides the gap and allows portability).
For the SQ&D I will use the CAVITYLITE at 40kg/m3. They don't come plastic wrapped as I have heard they do in the US/EU. Is it ok then to completely cover with batting and burlap? Would a 0.25-0.5" thick layer of batting suffice to keep the fibers in or must it be 1-2" thick as in the panels?
I read those posts and now understand the concerns. I see the main problem is inconsistent/unknown density. This may be a dumb question, but the ones I can get come in varying, published densities (they call it 'nominal density') - is the published densities the fiberglass WITHOUT the bonding resins, ie. the density of the raw fiberglass before being moulded into pipe shapes?
Finally for your SQ&D's - since 2x1m rolls may not be very sturdy on their own, is it ok to have two MDF/drywall endcaps and one in between the two rolls, to make a more sturdy 2m tall x 16" diameter trap?
Thanks and cheers,
X
[ Is it ok then to completely cover with batting and burlap? Would a 0.25-0.5" thick layer of batting suffice to keep the fibers in or must it be 1-2" thick as in the panels? ]It depends on the polyester density. The Hi-Loft type I recommend is at aprox. 0.5 to .7 lbs per cu. ft density, and thus, a 3/4" thickness is just enough to provide containment, while a lower density would need more thickness, and I would NOT recommend a much higher density (nothing over 1 lb. cu/ft)
[ is the published densities the fiberglass WITHOUT the bonding resins, ie. the density of the raw fiberglass before being moulded into pipe shapes? ]
I don't believe so, based on my own experiments and examination of the steam pipe insulation.
[ Finally for your SQ&D's - since 2x1m rolls may not be very sturdy on their own, is it ok to have two MDF/drywall endcaps and one in between the two rolls, to make a more sturdy 2m tall x 16" diameter trap? ]
Sure, but just the drywall endcaps by themselves will not provide that much more stability, without an outer shell (wire fence, etc) to help provide support. In the US < with the rolls compressed quite a bit, and wrapped tight, then inside a plastic bag, you can stack two or three high, and they will not tip over too easily, esp. once the bage are taped together, and they assembly covered in batting and burlap pulled taut.
Jon Risch
Hi There,Thanks once again. I am pretty set now, gonna order those rolls and the other materials I need.
Since the pipe covering is the actual published density, would a pipe of around 40kg/m3 not be effective then? I perceive how yours would be perhaps more effective due to the sheer amount of fiberglass, but what about the pipes filled in the center with loose fiberglass. I am asking now mainly for interest since I have decided to give the SQ&D's a go, but it would be interesting to find out how a 40kg/m3 pipe would perform. Also for some reason the pipe coverings are much cheaper here than fiberglass rolls - about 1/2 the price.
Just one last question - do the plastic bags which cover the fiberglass rolls have another purpose besides containment? Do they act as some form of diffusor/reflector? My room is very lively with a fair amount of echo, so with the rolls simply covered with batting and burlap I believe the bass traps may also aid to HF absorption correct?
Thanks for the help once again. Will let everyone know once my SQ&D's are ready and report the results.
Cheers,
X
Hi There,Just had one more question - those rolls of fiberglass which you can get in the US and are around 16" diameter - what is the length of the roll (if you were to roll it out completely)? The reason I ask is that I found out that the rolls I get here come in 8-10m lengths and are very expensive (compared to the pipe covering).
I thus wanted to try and determine roughly how many bass traps I could make from a single 8m long x 1.2m wide x 40mm thick roll (40kg/m3). These rolls cost about $100 each, whilst the pipe coverings, which are 1m long x 300mm internal diameter x 400mm external diameter (ie. 50mm thickness of fiberglass) and 40kg/m3 cost about $20 each.
Cheers,
X
Quick update - the only fiberglass I can get which is the same price as the pre-formed pipe coverings is Aerolite but that is only 11kg/m3 - is that not dense enough? I see it has an NRC of around 0.8, whereas what I wanted to use originally (40kg/m3 CAVITYLITE) has an NRC of around 0.95. I have read your posts again about why the SQ&D traps are better than using pre-formed pipes, but at $100 for the cavitylite roll it seems cost prohibitive. If the Aerolite is good enough though then I will definitely use that.Cheers,
X
Teh density unrolled is not as critical as the density when it is still rolled up. It maybe that the 11kg/m3 stuff will be fine when it is rolled up.
Jon Risch
Hi There,Thanks for the confirmation. I did some further searching and am pretty sure it is the stuff, since I calculated that a roll ends up being R-19 which others on the board have said they have used (R-value is 1.88 per m2, and there is 10m2 per roll). Also they say when they did not cover it up they had a pink panther staring at them :) which pretty much certifies the stuff, since that is Aerolite (think pink) which is a global brand of insulation.
I have ordered some from a store and it should be here soon. Will post results when I have played around.
Thanks for the all the help Jon, much appreciated.
One quick question about absorption panels, now that the bass traps are sorted - I have seen people making DIY panels linke those on your site consisting of the frame, inside of which there is a 1-2" rigid fiberglass board, on top of which is 6-8" fiberglass, lightly compressed, then the usual batting/burlap to cover. Do you know if this would be more or less effective than the previous design we talked about which was a 1" rigid fiberglass board of around 80kg/m3 then a 2" thick board of around 40kg/m3 then batting/burlap. In other words, replacing the 2" board with around 6-8" of this think pink fiberglass.
Cheers and have a good day,
X
Based on my own expriences and testing, the 6-8" of fiberglass will overall outperform the 2" board, no matter what density. However, it will be a lot thicker on the whole too.
Jon Risch
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