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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Wall Fabric vs. Acoustic Panels (Page 1)

 
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Author Topic: Wall Fabric vs. Acoustic Panels
Lyle Romer
Phenomenal Film Handler

Posts: 1383
From: Davie, FL, USA
Registered: May 2002


 - posted 06-23-2006 10:04 AM      Profile for Lyle Romer   Email Lyle Romer   Send New Private Message       Edit/Delete Post 
I'm wondering what the pros and cons of wall fabric vs. acoustic panels are in an auditorium. I'm mostly talking from a technical/sound standpoint. Aesthetically, I prefer panels but some people may like fabric better.

I noticed in the studio movie grill pictures that they used wall fabric. Back in my GCC days, I worked at an older (1985 build?) location. All auditoriums had all walls completely covered in acoustic panels. They later moved to completely covered in THX auditoriums and large acoustic panels with some bare wall showing in non-THX auditoriums.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16269
From: Bountiful, Utah
Registered: Jun 99


 - posted 06-23-2006 11:40 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Fabric does almost nothing by itself. You still will need to put from 2" to 4" of acoustical material up behind any fabric... depending on your acoustical consultants analysis... before you place the wall coverings over the acoustical panels on the wall. I prefer the look of Acoustical panels fror an astetic viewpoint but it also depoends on the motif of the theater interior. Wall fabrics tends to be a dust magnet.... Hire a consultant!

Mark

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Richard Fowler
Film God

Posts: 2389
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001


 - posted 06-23-2006 12:07 PM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
Pleated drapery setups like Soundfold will offer some improvement due to the 33% or 50% pleating density. They work much better if behind the drapery there is 1 to 2 inch fiberglas duct liner material, 100% on back wall and at least 50% coverage on the side walls. Wall panels are generally Guilford fabric over rigid 1 inch fiberglas panels ( basically fiberglas rigid duct material ); generally do not do as good a job of sound absorption versus sewn or bracketed drapery. Panels are also a problem if contruction changes at the site are different than the specs supplied to manufacture the panels. There are published sound absorbtion specs for panels and drapes + computer programs to figure problem point of a space based on speakers used and room dimensions.
I recently finished a performing arts center with thick, pleated side curtains for film / video; they are stored in eight variations revealing plaster walls to "liven" the room for stage performances [Cool]
Dirty drapes....must be that cheap burlap that was popular 25 years ago [puke]

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16269
From: Bountiful, Utah
Registered: Jun 99


 - posted 06-23-2006 02:32 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
quote: Richard Fowler
Dirty drapes....must be that cheap burlap that was popular 25 years ago

I have not seen too many pleasted jobs in a long time but many 10 to 15 year old locations are fairly dusty.... Alot of the western states are just dusty places to begin with and there is not much you can do about it except vaccum off your soundfold. To me Soundfold just plain looks out of style and old school. There are way too many nifty things that can be done with sound panels... at least if its done right. Again... use an acoustical consultant on a big job. I doub't than any of us here could properly do the job of a pro acoustical consultant that has much theater expereince.

Mark

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3671
From: Dallas, TX
Registered: Nov 2000


 - posted 06-23-2006 04:33 PM      Profile for Adam Martin   Author's Homepage   Email Adam Martin       Edit/Delete Post 
quote: Mark Gulbrandsen
many 10 to 15 year old locations are fairly dusty
Maybe if they stopped using that leaf blower in the auditorium and changed the HVAC filters regularly ... oh wait, that would cost money.

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Richard Hamilton
Phenomenal Film Handler

Posts: 1341
From: Evansville, Indiana
Registered: Jan 2000


 - posted 06-23-2006 04:56 PM      Profile for Richard Hamilton   Email Richard Hamilton   Send New Private Message       Edit/Delete Post 
I recently did a service call at a multiplex. When I first arrived, I looked at the presentation of each feature and the sound was pretty bad, except for their 2 big houses. Everything sounded hollow and echoey. Upon inspection of the room, I found that behind the "soundfold like" fabric, it was bare drywall, on every wall. Behind the screen speakers was bare concrete block. I looked at the first room on the analyzer and just told the owner that I would only make sure the sound equipment was operational, I couldn't make it perform beyond what it was capable of. Bad Design, but now he knows for future projects.

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Richard Fowler
Film God

Posts: 2389
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001


 - posted 06-23-2006 05:12 PM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
The more dead the room, the easier to do something with [Wink] Soundfold with certain fabrics and wide spaced economy pleating does not do much....with surround speakers cross firing, even less...but it is a start from a bare wall. Room geometry plays greatly in sound quality.

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Lyle Romer
Phenomenal Film Handler

Posts: 1383
From: Davie, FL, USA
Registered: May 2002


 - posted 06-23-2006 09:23 PM      Profile for Lyle Romer   Email Lyle Romer   Send New Private Message       Edit/Delete Post 
quote: Richard Fowler
Room geometry plays greatly in sound quality.

Isn't the idea to use the acoustic panels/fabric to "deaden" the room and take the room geometry out of the equation as much as possible. Obviously you can't completely take it out unless you build the auditorium as an anechoic chamber. It'd probably be hard to maintain the pointy foam cones on the floor though!

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Tommie Evans
Expert Film Handler

Posts: 116
From: Birmingham, West Midlands, UK
Registered: Sep 2004


 - posted 06-23-2006 09:47 PM      Profile for Tommie Evans   Email Tommie Evans   Send New Private Message       Edit/Delete Post 
quote:
It'd probably be hard to maintain the pointy foam cones on the floor though!

Unless you cover the floor with seats and people? [Wink]

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Cameron Glendinning
Jedi Master Film Handler

Posts: 844
From: West Ryde, Sydney, NSW Australia
Registered: Dec 2005


 - posted 06-23-2006 11:10 PM      Profile for Cameron Glendinning   Email Cameron Glendinning   Send New Private Message       Edit/Delete Post 
You do not need to use either heavy drapes or acoustic panels, you can also use plaster, 3d shapes, non parallel walls. The aim is to break up the sound on its first bounce. In my opinion deadening backstage is the most important factor, early reflections are what makes dialogue hard to understand.

Here is a photo of the first cinema I custom built a complete speaker system/ cinema opened 1995 First art modern cinema built in 40 years in Sydney Australia
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Within 3 months of opening, The Audio Guild (sound mixers) forced the Australian Film Institute to hold the NSW Judging for audio category AFI Awards in only this screen.

Backstage is damped by fiberglass, weight is the important factor, 3.5 kilos per sq metre. Components by JBL when they actually made them, before the parts were consigned from asia.
On the walls no curtains, acoustic panels, just deliberate use of plaster work to break up sound.
Ported boxes backstage incorporated large 1/4 wavelength designed wings.
This theatre is long and narrow and holds aprox 350, traditionally a bad shape as the ideal acoustically would be 0.6 x 1 x 1.6 the traditional Egyptian pymamid brick shape that most speaker boxes are based on.

My later systems moved away from the ported design in preference for an extremely large sealed box known as the infinite baffle box with 1/4 length wavelength wings, similar to altecs final approach to cinema systems before they disappeared. This aproach created the most realistic and natural results before going to the expense of a totally active 4 way horn loaded system.

Speaking of which, When the Chauvel re opens here in Sydney, it looks like this will be the type of system installed. www.lenardaudio.com
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This is the sub and mid bass only, enclosures are aprox 18" deep, 3.5 metres high( 11 ft? ) Sounds incredible!!!
Also 4 way horn loaded systems still sound very good in rooms with poor acoustics, which I confess, I dont understand why.

[ 06-24-2006, 12:50 AM: Message edited by: Cameron Glendinning ]

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Dan Lyons
Jedi Master Film Handler

Posts: 698
From: Seal Beach, CA
Registered: Sep 2002


 - posted 06-24-2006 01:44 AM      Profile for Dan Lyons   Email Dan Lyons   Send New Private Message       Edit/Delete Post 
[Eek!] [Eek!] [Eek!] GORGEOUS!!!!

What's the jumble of white stuff and railings up front on the right?

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Paul Trimboli
Master Film Handler

Posts: 274
From: Perth Western Australia
Registered: Dec 2002


 - posted 06-24-2006 09:02 AM      Profile for Paul Trimboli   Email Paul Trimboli   Send New Private Message       Edit/Delete Post 
Wow that is a nice looking cinema Cameron, where abouts is that?

I always wondered how some of these old cinemas could have such good accoustics with out the pading type acoustic panels or heavy curtains, but as you explained you can use plaster and 3D shapes. That explains hows this cinema I used to work at picture below can have such good accoustics, although some of the wall is covered in acoustic tiles. They are sort of an airated plaster which I think I was told is packed with hair?

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16269
From: Bountiful, Utah
Registered: Jun 99


 - posted 06-24-2006 09:52 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Nice theater Cameron! I've always had a problem with full horn loaded systems sounding naisley on dialog though... at least thats been my expereince here with the systems made by the big "K".

MArk

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Charles Greenlee
Jedi Master Film Handler

Posts: 801
From: Savannah, Ga, U.S.
Registered: Jun 2006


 - posted 06-24-2006 11:40 AM      Profile for Charles Greenlee   Author's Homepage   Email Charles Greenlee   Send New Private Message       Edit/Delete Post 
Very nice look to it. Real ultra modern looking. As far as sound material goes. I like the old school look with the curtains, was well as screen curtains (in addidtion to the masking). It just adds that extra touch. But the theatres that have them need to make sure they back them with accoustical panels, for sound purposes, and for gods sake, take them down and have them cleaned occasionally. I hate smelly, dusty auditoriums, with gum imbeddded in the curtains. And yes, I have the leaf blower thing, it's hard enough to get the cleaning crew to mop our floors. It's like, its dark, alot of kids, 55oz. badder burster coke = sticky floor. Sorry for the anger, but anyhow, curtains look nice. And you never know, maybe a combo of curtains and panels, depends on how it looks.

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Richard Fowler
Film God

Posts: 2389
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001


 - posted 06-24-2006 04:05 PM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
You do not always need sound deadening in a properly designed performance area but most multiplex construction is basically a dressed up warehouse space [Roll Eyes] . Bellas Artes Performing Arts Center in Caracas, Venezeula has wooden strips with acoustic traps in the angled side walls to great effect. Gusman Theatre in Miami, a classic atmospheric, we found the acoustics and sound projection good enough that after a sound check with Dame Joan Sutherland on her farewell Opera tour, her lead microphone was not used since she was clearly heard all away to the back of the house ( 136 feet / 61.8 meter ). Mark's note on "K" 4 way system being a pain to EQ....they sound better with electronic crossovers than the passive units. JBL is making some parts out of the USA but compared to some of their competition, not as bad. Their Main office and Plant in Northridge, California is something to see since they have 12 - 15 mini-manufacturing stations with most able to be rapidly retooled for different runs [Razz] .

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