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Topic: sound proofing techniques?

Mike Jones
Expert Film Handler

Posts: 108
From: Birmingham, MI, USA
Registered: Jul 2000

posted 07-06-2000 06:40 PM

Our 8 screen theatre was built fairly well to deal with sound bleed from adjacent theatres. However, sound comming from the booth was not thought about enough. I can safely say that in everyone of our theatres you can hear the projector clicking in quiet parts of the movie. Also in some cases, guests can hear what the projectionists are saying through the walls. Yikes! We have standard sheetrock walls and simple window pains for portholes. Being named "the best place to see a movie in detroit," i figure we could probably work on our noise problem. Does anyone have any ideas on how to fix this problem?

Thanks in advance,
Mikey J.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 07-06-2000 06:56 PM

The booth wall should be doublestudded just like the other auditorium walls
The port is the usual culprit and Dolby has information on building sound proof ports

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 07-06-2000 09:44 PM

In a previous posting topic, we talked about port window design. Try using the search function.

I would tell you the date and topic title, but when I tried to do a search, I got; "500 Error - Internal Server Error"

Also, you could call THX. They were very helpful to me when I asked about port windows.

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999

posted 07-06-2000 10:22 PM

The latest istallation I did, featured non-openable port-glass that was sealed with silicone (or other caulking) around the glass. Fortunately, all auditoriums featured stadium seating, so cleaning the auditorium side of the glass was not too big a deal (although the observation port can be a bit of a bitch to reach in some cases).

At first, I was not impressed, but as the installation progressed, I noticed two things.
(1) The booth stayed a lot cleaner during the installation.
(2) Sound transferance from the booth to the auditorium was reduced considerably to the point where, when holding a sound meter while doing auditorium level sets, and communication was necessary with the guy in the booth, we had to run up to the port and shout loudly at the glass to be heard on the other side (usually only necessary to avoid confusion with surround level settings for EX).

If it is practical in your situation, an inexpensive solution might be to silicone around the glass edges of all openings to the auditoriums.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 07-07-2000 07:09 AM

Kelmar Systems markets double-pane ports:
http://www.kelmarsystems.com/page24.html

Goldberg Brothers also sells port systems:
http://goldbergbrothers.uswestdex.com/goldbergbrothers/Page2.html

Port glass should be optical quality, with anti-reflection coatings. It should be angled to the projection beam, such that it does not reflect light back into the lens. If double panes are used for acoustic isolation, they should NOT be parallel to each other, to avoid contrast-reducing re-reflection between the two panes.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

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Jason Burroughs
Jedi Master Film Handler

Posts: 654
From: Allen, TX
Registered: Jun 99

posted 07-07-2000 01:01 PM

One theatre that I was at used the Kelmar Port windows, and I was VERY unimpressed. Althought the ones that I worked with were single pane the design looks to almost exactly the same. The magnetic strip to hold the glass in place never works and with stadium seating customers can reach the windows and easily push them in, resulting in expensive broken glass all over the place.

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Francis Casey
Film Handler

Posts: 44
From: Saint John, NB, Canada
Registered: Jun 2000

posted 07-07-2000 01:05 PM

Rick
Just curious, but how did you do the EQ if you couldn't open the port to throw your RTA cable through ?
Francis

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Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!

Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999

posted 07-07-2000 05:07 PM

Francis Said:
"Just curious, but how did you do the EQ if you couldn't open the port to throw your RTA cable through ?"

The same way I have had to do with several auditoria that have the completely idiotic siliconed-in unopenable windows....Break a HOLE through the wall and pass your cables thru as you curse the people who designed the booth ports...

While I have only had to do it the aforemantioned way only once, I have added a pipe or other port to pass wires thru other booths, makes it easier and less damaging

Aaron

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999

posted 07-07-2000 06:32 PM

Yes, at first we were indeed tempted to smash a hole in the wall where it would not be noticed. Instead cooler heads prevaled, and we used the mike (p.a.) line going from the sound rack to back-stage. A few dozen feet of shielded cable and a quarter-pound of aligator clips later, we connected the mike box from the auditorium to the RTA.

I did talk to one of the architects, who paid a visit during the installation, and I got at least a promise of consideration about installing a piece of 2" PVC pipe, with threaded closeable ends, through the wall on fuure installations, such that the auditorium end would be behind a seat and generally invisible to the audience.

Whether this matter was forgotten before he even left the building remains to be seen.

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