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From: Bob Howes on 6 Nov 2007 01:14

<bigsphinx(a)gmail.com> wrote in message
news:1194283074.264816.258480(a)o3g2000hsb.googlegroups.com...
>I have a 70' x 35' room that I intend to use as a performance hall,
> for music ranging from noisy metal bands to acoustic/chamber music.
> Concrete floor, 12' high concrete-block walls. The roof is 18' high
> in the middle. We'll put in thick fiberglass insulation on the
> ceiling, and leave the rafters open (A/C duct and main house speakers
> will go up there too).
>
> The concrete floor will remain uncovered, but we obviously need to
> treat the walls. I've been advised to install 4' x 8' sheets of
> styrofoam insulation over most of the wall, and to cover them with
> fabric to make it all look better. (I plan to use thick stage
> curtains behind the stage and on either side of the audience, so that
> I can expose the bare walls as needed during acoustic shows.)
>
> Has anyone here installed foam panels in this way? What kind of
> fabric did you use? How did you attach the fabric to the foam, and
> the panel to the wall? How durable did it turn out to be? Did it
> dampen the sound as much as you'd hoped?
>
> Or, does anybody have some better ideas for treating these walls?
>

Pedantry alert. If "dampening" is what you want, set off the fire
sprinklers. I think what we're talking about here is "damping".

Seriously, I think the best advice so far is to get the services of a
trained acoustic engineer. Acoustics is the nearest thing to a "black art"
that I know and every situation is different...but the results I've had
using specialists have been amazing.

However, one type of treatment I once had recommended to me by a
professional was as follows:

Install 4 inch vertical battens on the walls to be treated. Fill the gaps
between the battens with high density rockwool. Cover the battens and
rockwool with perforated hardboard (sometimes called pegboard). There are
variations of this board with varying numbers of holes...you want the one
with the most holes per square inch. Finally, cover the pegboard with a
fabric (such as hessian) for appearance. Make sure the fabric and wood have
been given a flame retardant treatment prior to use.

The above worked sufficiently well when we had to convert a large storeroom
to a broadcast studio temporarily at one point. The real studio we were
building had BETTER acoustics, but this was okay!

Bob



From: bigsphinx on 6 Nov 2007 12:15
Thanks to all for the great ideas!

I'm afraid I may have mis-represented the advice of my advisor here.
I'm not sure he said "styrofoam" when suggesting the fabric-covered
4x8 panels... I know he did say "flame-retardant" for the covering and
the curtains, I just neglected to mention that here. But I'll be
meeting with him again soon... THIS time I'll write down what he
says...

Regarding the use of the hall, I should clarify that it'll be
optimized for loud metallic rock, but that I want to be able to adjust
the room (with the curtains) for acoustic (though mic'd) music as
well. I guess unamplified chamber ensembles might be a bit of a
stretch for such a venue, now that I think about it. (It's not
fair! Why can't I have everything?)

Anyway, I'll certainly take all this advice into consideration. And
I may well have further questions...

From: Arny Krueger on 6 Nov 2007 17:08

<bigsphinx(a)gmail.com> wrote in message
news:1194283074.264816.258480(a)o3g2000hsb.googlegroups.com...

>I have a 70' x 35' room that I intend to use as a performance hall,
> for music ranging from noisy metal bands to acoustic/chamber music.
> Concrete floor, 12' high concrete-block walls. The roof is 18' high
> in the middle. We'll put in thick fiberglass insulation on the
> ceiling, and leave the rafters open (A/C duct and main house speakers
> will go up there too).

I was recently in a larger room with a similar shape, and similar treatment
of the ceiling. It was a basketball court. One difference was that there
were folding bleachers pushed back along the wall. The acoustics were not
all that bad.

> The concrete floor will remain uncovered, but we obviously need to
> treat the walls.

Have you listened to it yet? The really bad-sounding rooms of this that I'm
familiar with don't have pitched roofs ( pitching increases the surface area
of the insulation) and didn't have the roofs completely insulated.

> I've been advised to install 4' x 8' sheets of
> styrofoam insulation over most of the wall, and to cover them with
> fabric to make it all look better. (I plan to use thick stage
> curtains behind the stage and on either side of the audience, so that
> I can expose the bare walls as needed during acoustic shows.)

Rigid styrene foam thermal insulation has minimal acoustic properties.

If you want to deal more effectively with reverberation, you need something
like Dow Corning 703 or the higher density (better bass absorbtion) 705.
Many large insulation contractors carry it. It's denser than thermal
insulation. I recently picked up a pack of 12 2'x4'x2" batts of 703 for
about $85 cash and carry. Competitive manufacturers of fiberglass insulation
like Johns-Manville have competitive products.

Thicker, denser sound absorbtion materials are more effective at the lowest
frequencies.

I find that rooms sound pretty reasonable when the floor and ceiling are
absorbtive, or the equivalent area is covered over-all including walls. If
the ceiling is low, that much absorptive material might actually make the
room a little dead. Commercial carpeting on the floor and a good grade of
acoustic tile on the ceiling can suffice. But all this outside the realms of
your project.

To echo what George said, it is paramount that your sound absorbing panels
be fireproof, which fiberglass is. Make sure that the fabric that you cover
it with is fire resistant as well.

Also, if you are going to spend a fair amount of money, or have a desire for
a good appearance, get professional design assistance. Another good
sound-absorbing material is Tectum.











From: Tim Perry on 6 Nov 2007 18:54

"bigsphinx" <bigsphinx(a)gmail.com> wrote in message
news:1194369313.124170.325140(a)o38g2000hse.googlegroups.com...
> Thanks to all for the great ideas!
>
> I'm afraid I may have mis-represented the advice of my advisor here.
> I'm not sure he said "styrofoam" when suggesting the fabric-covered
> 4x8 panels... I know he did say "flame-retardant" for the covering and
> the curtains, I just neglected to mention that here. But I'll be
> meeting with him again soon... THIS time I'll write down what he
> says...
>
> Regarding the use of the hall, I should clarify that it'll be
> optimized for loud metallic rock, but that I want to be able to adjust
> the room (with the curtains) for acoustic (though mic'd) music as
> well. I guess unamplified chamber ensembles might be a bit of a
> stretch for such a venue, now that I think about it. (It's not
> fair! Why can't I have everything?)
>
> Anyway, I'll certainly take all this advice into consideration. And
> I may well have further questions...
>

I am trying to imagine a room optimized for metallic rock. I just cant.

I would agree that hanging the speakers out of harms way is a good idea.

You might get some free help from aplication engineers at one of the
accustic supply companies like Sonex or Auralex.


From: Slim on 8 Nov 2007 22:45
On Nov 5, 12:17 pm, bigsph...(a)gmail.com wrote:
> I have a 70' x 35' room that I intend to use as a performance hall,
> for music ranging from noisy metal bands to acoustic/chamber music.
> Concrete floor, 12' high concrete-block walls. The roof is 18' high
> in the middle. We'll put in thick fiberglass insulation on the
> ceiling, and leave the rafters open (A/C duct and main house speakers
> will go up there too).
>
> The concrete floor will remain uncovered, but we obviously need to
> treat the walls. I've been advised to install 4' x 8' sheets of
> styrofoam insulation over most of the wall, and to cover them with
> fabric to make it all look better. (I plan to use thick stage
> curtains behind the stage and on either side of the audience, so that
> I can expose the bare walls as needed during acoustic shows.)
>
> Has anyone here installed foam panels in this way? What kind of
> fabric did you use? How did you attach the fabric to the foam, and
> the panel to the wall? How durable did it turn out to be? Did it
> dampen the sound as much as you'd hoped?
>
> Or, does anybody have some better ideas for treating these walls?

As others have mentioned - the styrofoam is not good - probably
illegal - and only good for keeping things cool or hot. A lot of
people in our area use wet blown cellulose. It's often blown into the
rafters and spray painted flat black. They add a fire retardant and
it's hard to notice it at all when the lights dim. Also about those
ducts. A club on the other coast has these way-cool cloth ducks that
poof out when air is forced into them and they just hang there when
it's off. They can be removed for washing. The best part is they're
quiet while in use. They're just big sealed cloth sacks that hang and
the air is forced through them. Many years ago there was a company
that made a plastic strip thing called "Fab-u-track" and it would hold
fabric like a stretched canvas. Some kind of white 1/2" puffy stuff
was stapled to the walls in back of the fabric. We did a big
corporate office in Tampa with it about 25 years ago.

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