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[Dan Andrews]

Thanks Brad,

That's what I though, and thanks for the web site info.

All the Best Dan

[Arnold B. Krueger]

I think it was a typo and Arnold was referring to this, http://commercial.owenscorning.com/products/pipe/fiberglas-700-series-insulation/.  The 700 series is compressed fiberglass board and the different models in the series (701, 703, 704, 705 and 707) relate to different densities (the last digit in the model number is roughly the density in pounds per cubic foot).  They're readily available in 1" or 2" thicknesses and either unfaced or with an FRK (Foil Reinforced Kraft) or ASJ (All Service Jacket) facing.

Exactly, and the unfaced products are what you want for just about any acoustics application.  Johns Manville and others have competitive products, and other products made from mineral wool have similar acoustical properties. If it is 2" thick, composed of fine fibers, and its density is about 5 pounds per cubic foot (which makes it like a board) then it probably does about the same thing to sound waves. Absorbers can also be made out of cotton or polyester, but those alternatives seem to be more costly. 

Higher density products seem to absorb lower frequencies better, which is why the materials used for acoustical treatments are generally far denser than the ones made for thermally insulating walls and ceilings. A friend of mine who does lab tests on these things says that it is very hard to pack these kinds of fibrous materials so tighly that they turn into reflectors.

So, if I had made my sound absorbers out of 2" thick fiberglass batts of the kind used as thermal wall insulation, the absorbtivity at say 100 Hz would have been far less and the quality of the results would have been audibly diminished.

[Greg_Cameron]

I read an article recently that stated the denim based "eco insulation" works better for sound panels than any of the fiberglass stuff. Anyone have any input on that?

Greg

http://www.bondedlogic.com/ultratouch-cotton.htm

[Arnold B. Krueger]

I read an article recently that stated the denim based "eco insulation" works better for sound panels than any of the fiberglass stuff. Anyone have any input on that?

http://www.bondedlogic.com/ultratouch-cotton.htm

My friends who pursue this kind of thing in the lab tell me that there is no magic related to fiberglass versus rock wool versus polyester versus cotton versus whatever. Given a certain kind of fine fiber and a certain packing density, they absorb sound by means of the same basic physical process and the results are pretty much the same.

What is different is how it feels to work with the various materials.

My house is insulated with rock wool, and the attic of our sanctuary at church is insulated with loose fiberglass. In either case wise people wear particulate masks, cover their bodies with long pants and long sleeves, and change their clothes and bathe within minutes of walking off the job. I think that rock wool is a bit nastier than fiberglass, but the difference is the difference between very ugly and very, very ugly.

Polyester and cotton batts can be messy, but they aren't nearly as nasty to work with a fiberglass or rock wool. I guess that people who work in factories with lots of cotton fiber dust in the air for decades can get a kind of lung disease,  but casual work with sound absorbers doesn't usually involve that sort of thing.

Sound absorbants are interesting when you consider that unpainted cinder block is about 1/3 as absorbant as high density fiberglass of similar area and thickness. Paint it and close the pores and its almost as nasty-sounding as glass or tile. However, split concrete blocks with a coarse surface can sound pretty good as diffusers.

Diffusion while expensive is not to be underestimated. The broadcasts of the recent royal wedding sounded pretty good to me  despite the fact that the majority of the absorbtion in the room was people.

[Andre Vare]

I read an article recently that stated the denim based "eco insulation" works better for sound panels than any of the fiberglass stuff. Anyone have any input on that?

Greg

http://www.bondedlogic.com/ultratouch-cotton.htm

For thicknesses up to 4" all the materials are similar at appropriate densities.  Ultratouch appears to have significantly higher gas flow resisitivity, making it worse for applications it is thicker than 4".

Andre

[Brad Weber]

Diffusion while expensive is not to be underestimated. The broadcasts of the recent royal wedding sounded pretty good to me  despite the fact that the majority of the absorbtion in the room was people.

It can be expensive to add diffusion after the fact, especially for some types of diffusers, however it may not necessarily as expensive to incorporate some forms of diffusion into the initial design and construction of a space.

[chris harwood]

I treated my control room in my studio and took before and after measurements.  The measurements were meaningless, as the results were stunning, that I didn't need to look at graphs and numbers.  I used Owens Corning 703 and made 4" deep absorbers and pretty much randomly placed them on the walls, attempting to hit the most obvious refection points (using a mirror against the wall and wherever I could see my speakers from my mix position, put an absorber.  I also straddled the corners with 4" material, 2 feet wide, from floor to ceiling.

I spent a good day making nice looking bass traps and about $350 in materials.  I would have spent $20k if I knew it would have improved imaging, tightened up the bass, and eliminated a pile of peaks and dips across the spectrum, as good as it did.

HIGHLY recommended.  I'd bet you could spend $5k in a typical 50x75 foot sanctuary, and have similar results.  It aint rocket science as some might have you believe.  Just do it "right"  !!

[Brad Weber]

I treated my control room in my studio and took before and after measurements.  The measurements were meaningless, as the results were stunning, that I didn't need to look at graphs and numbers.  I used Owens Corning 703 and made 4" deep absorbers and pretty much randomly placed them on the walls, attempting to hit the most obvious refection points (using a mirror against the wall and wherever I could see my speakers from my mix position, put an absorber.  I also straddled the corners with 4" material, 2 feet wide, from floor to ceiling.

I spent a good day making nice looking bass traps and about $350 in materials.  I would have spent $20k if I knew it would have improved imaging, tightened up the bass, and eliminated a pile of peaks and dips across the spectrum, as good as it did.

HIGHLY recommended.  I'd bet you could spend $5k in a typical 50x75 foot sanctuary, and have similar results.  It aint rocket science as some might have you believe.  Just do it "right"  !!

I keep saying this, but while home studio acoustics and large room acoustics share many commonalities, there are also many differences.  Some are technical, e.g. tending to be modal versus rebverberant controlled and the time relationships between reflections and the direct sound, while others are functional, e.g. looking at a small and specific listener position versus a large listener area, and code driven.  Maybe you can indeed make big changes for a relatively small investment, but there are good reasons that you'd usually approach the audio in a studio and Sanctuary quite differently and similar logic also applies to acoustics.
 
Also, acoustics for Sanctuaries and similar spaces is not limited to adding finishes after the fact, it should not only extend into aspects such as room dimensions and room shape but can also encompass aspects such as mechanical system noise and vibration control and interior and/or exterior sound isolation.

[chris harwood]

I keep saying this, but while home studio acoustics and large room acoustics share many commonalities, there are also many differences.  Some are technical, e.g. tending to be modal versus rebverberant controlled and the time relationships between reflections and the direct sound, while others are functional, e.g. looking at a small and specific listener position versus a large listener area, and code driven.  Maybe you can indeed make big changes for a relatively small investment, but there are good reasons that you'd usually approach the audio in a studio and Sanctuary quite differently and similar logic also applies to acoustics.
 
Also, acoustics for Sanctuaries and similar spaces is not limited to adding finishes after the fact, it should not only extend into aspects such as room dimensions and room shape but can also encompass aspects such as mechanical system noise and vibration control and interior and/or exterior sound isolation.

I can't disagree but would hope anyone with a head on their shoulders would realize all that.  Obviously doing it right from the beginning during a build is MUCH better than a "fix". I was only wanting to illustrate a good end result, even though for all the differences you went to the effort to detail.

I have been in sanctuaries with fiberglass plastered on the walls... and looking good, that worked VERY well.  Even as a "fix".
Can't also disagree that once spaces get to a certain size, diffusion should come into play.  After all, you don't want your sanctuary to sound like a "library" and completely isolate your congregation.  That's just weird acoustics.

edit...oops spelling...watch out..maybe more!!

[Brad Weber]

I can't disagree but would hope anyone with a head on their shoulders would realize all that.  Obviously doing it right from the beginning during a build is MUCH better than a "fix". I was only wanting to illustrate a good end result, even though for all the differences you went to the effort to detail.

I appreciate what you were trying to do and hope others do as well.  However, I've been surprised how many people dealing with larger spaces, including churches, seem to get ideas for DIY acoustics directly from the numerous home studio and home theatre resources that are so readily available.  And also how many think only of room finishes when thinking of acoustics without considering how acoustics can extend into aspects of the space design such as room shaping, room volume, space planning, HVAC system design, etc.  It's not a church but I'm currently working on the acoustics for a $350+ million building and the vast majority of my time is being spent on HVAC system noise and vibration control, interior and exterior sound isolation, space adjacencies and so on.