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Author Topic: JBL Imax Speakers
Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000


 - posted 09-01-2003 06:25 PM      Profile for Antonio Marcheselli   Author's Homepage   Email Antonio Marcheselli   Send New Private Message       Edit/Delete Post 
Hi Everyone

I've heard that JBL makes special speakers for IMAX screens. Can anyone tell me a place where can I found some tech specs of these speakers?

Bye
A

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Gordon McLeod
Film God

Posts: 9389
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 09-01-2003 08:32 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
Sonics (a division of IMAX) was originally a parnership between Oxmoor and Imax. They built there own proprietary timealigned speakers (similar to the frazier CATS but bigger and actually work)
The drivers are usually JBL

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Richard Fowler
Film God

Posts: 2381
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001


 - posted 09-01-2003 08:38 PM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
The main facility at the headquarters in California has a large custom shop for production of products designed for or using specifications supplied by client's under contract.....so it is possible. IMAX owns a sound company ( Sonics )that was promoting their custom brands to dealers a few years ago...The announced increase of IMAX screens over the next few years may have prompted some outsourcing. The main production floor at the Balboa Avenue facility is something to see....basically about 15 - 20 mini production lines turning every thing from driver - woofer components to finished products on one huge floor.

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Gordon McLeod
Film God

Posts: 9389
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 09-01-2003 08:43 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
The drivers are all standard JBL components in the "classic systems"

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Dave Macaulay
Phenomenal Film Handler

Posts: 1930
From: Toronto, Canada
Registered: Apr 2001


 - posted 09-01-2003 09:07 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
My understanding is that Sonics as such is gone. Oxmoor, which was closely related and made studio equipment as well as some Sonics stuff, may still be alive. I think the Sonics field techs (that wanted to) are now Imax field techs and also do projector service and the Imax techs are expected to do sound service, although the cross training may not be complete yet.
The Sonics speakers were designed in-house and used various drivers, I don't believe all were JBL. They all sounded pretty good to me, but the latest design large system was quite impressive. Unfortunately the sound system price was stunning as well.

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Paul Trimboli
Master Film Handler

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


 - posted 09-01-2003 09:25 PM      Profile for Paul Trimboli   Email Paul Trimboli   Send New Private Message       Edit/Delete Post 
So why are the IMAX speaker so good!? How is it that the sound so amazing? I am thinking of getting the box design and trying to build one from generic drivers and see how it sounds.

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Gordon McLeod
Film God

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From: Toronto Ontario Canada
Registered: Jun 99


 - posted 09-01-2003 10:42 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
be aware that drivers are box size specific and fussy about loading
There stuff was built like the preverbial "brick shithouse"
Oxmoor is still in business
Sonics did attempt to market a THX approved regular theatre system called the S3 that actually had a patern controled horn for the lobing of a statium theatre

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Paul Trimboli
Master Film Handler

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


 - posted 09-02-2003 08:12 AM      Profile for Paul Trimboli   Email Paul Trimboli   Send New Private Message       Edit/Delete Post 
What is the science behind their design? They don't use the speaker coloum effect of stacked drivers, since the horn is in the middle with the other drivers above and below them?

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Dean Kollet
Jedi Master Film Handler

Posts: 591
From: Florida State University
Registered: Jul 2003


 - posted 09-02-2003 09:10 AM      Profile for Dean Kollet   Email Dean Kollet   Send New Private Message       Edit/Delete Post 
I don't know too much about speaker design, but I think that IMAX Theaters sound so good has to do a LOT with the amplification and sound insulation just as much as the design of the speakers do. Even at the theater I work at (20 Screens; 20 SDDS, 4 DTS, 3 Dolby Digital), the medium screens with almost the same amplification as the larger screens sound better...why? The theater is insulated more, it's set more in the core of the building, and the speakers aren't having to work too hard. We recently got an IMAX theater in Tallahassee and the amplification if INSANE for their setup. Our big house has a larger screen and twice the seating, but the audio equipment isn't really payeed attention to that much. I may raise a bit of a debate, but I'm gonna say that the AMP makes the speaker to a certain extent. You give a speaker enough clean power (something most amps just don't deliver today) it will sound great. If you don't belive me, take an Old McIntosh Tube Amp from the late 70's and hook it up to a modern day speaker....let me know how good it sounds :-)

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Dave Macaulay
Phenomenal Film Handler

Posts: 1930
From: Toronto, Canada
Registered: Apr 2001


 - posted 09-02-2003 10:38 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Sonics in general put performane before economy with their Imax systems. The speakers were designed as time-aligned, simulating point sources and the larger ones are 4-way with active crossovers and 4 amp channels. The odd layout is to produce an approximation of a point source. Their sub-bass systems are massive stacks of sealed cabinets facing into a slot, I don't know the theory but they are bastard loud!
The equalization is via Oxmoor 1/3 octave programmable units, and the actual setup done from inside the auditorium using fancy test equipment to do a rough setup then final setup by ear - which usually took most of a day.
I think the attention to detail in thge accoustic treatment has a lot to do with the final sound. They would do a scan of the room that showed a time/sound screen, then start looking around with "something 15.4 meters from the mic is causing a reflectance", then find the problem spot and have it fixed by the accoustic contractor.
The EQ also had something like 64 preset banks, so you get a film EQ, a music EQ, and a PA EQ. Plus the ability do have special EQ for each film if you really wanted to spend the time.
Tome costs money, and the astronomical price tag for the Imax sound systems showed that.
I doubt if many (if any) standard cinemas have put the effort into accoustic design and system tuning that Sonics did for Imax rooms. The speakers are a part of the final result, but all the detail work on the room itself probably contributes more.
And finally, tuning the system by ear from inside the room will always be the right way. Setting up a system with an analyzer from inside the booth is better than doing nothing - but it isn't "doing it right".

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Bobby Henderson
"Ask me about Trajan."

Posts: 10515
From: Lawton, OK, USA
Registered: Apr 2001


 - posted 09-02-2003 06:26 PM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
I don't know a whole lot about IMAX speakers, other than what I see when I enter an IMAX-branded theater. The enclosures and drivers are typically much larger than a typical theatrical stadium seated theater. LOTS more amplification.

The way I see it, IMAX does stadium seated auditorium sound fairly correct. There's room for improvement in terms of surround coverage, but it usually beats the crap out of most any 35mm room with stadium seating.

The obvious problem with 35mm theatrical rooms with stadium seating is they typically use stage and surround enclosures that are designed for small, normal slope auditoriums. And they don't put in enough amplification. In the end, you get thin, weak sound. I'm surprised that any of those kinds of houses get approved for THX certification. The way they typically sound, I strongly doubt if they really pass all the tests.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11693
From: Annapolis, MD
Registered: Dec 1999


 - posted 09-02-2003 08:38 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Despite the hype...the typical theatre speaker really has an easier time with a stadium theatre than with a slope floor.

The typical horn has a vertical dispersion of40-degrees which will cover most stadiums just fine. On a slope floor the distance from front to rear seating can be much longer and therefore harder to evenly cover.

On the surround side, things are more difficult. On has the rear patrons with the seats practically at the speakers where in the front they can be some distance away. I've been known to use different speakers for side and rear walls just to avoid coverage issues.

Steve

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Bobby Henderson
"Ask me about Trajan."

Posts: 10515
From: Lawton, OK, USA
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 - posted 09-03-2003 01:26 AM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
Stadium seated theaters usually have a much higher amount of cubic airspace to cover than a normal sloped auditorium with the same number of seats. The stadium seating angle might help stage speaker coverage, but all that added airspace filters out a lot of its strength.

Usually the only stadium seated theaters I find with decent sound (not counting IMAX) are the smaller auditoriums. Big ones are typically plagued with echo problems and thin sound. I think IMAX has a valid point in using a much more expensive approach to their auditoriums. For oversized 35mm stadium houses, the IMAX approach on sound needs to be copied in some way.

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Dave Macaulay
Phenomenal Film Handler

Posts: 1930
From: Toronto, Canada
Registered: Apr 2001


 - posted 09-03-2003 10:32 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Imax historically has hada "do it right" approach, while megaplex chains generally have a "do it cheap" approach. There are Imax rooms that sound bad - Gord will probably admit that CInesphere, with its worst-case architecture (a dome) has severe problems with sound focusing and indistinct localization of sound sources from many seats. That space was built before a use was decided and Imax barely existed at the time - Imax projector #1 went into Cinesphere after the debut at Expo70 in Osaka but the building wasn't designed as an Imax theatre.
Imax design practice is to use acoustic wall treatments on all surfaces possible, plus the backscreen wall usually gets 6" of duct liner. The only untreated reflective surface in many Imax rooms is the port glass.
AMC (for example) uses no acoustic treatment on the side walls but they angle them inward a few degrees so that slap echos attenuate faster, and they put one 1" layer of duct liner on the screen wall if the screen is perforated. The non-perf screens (20 of 24 screens at a typical 24) get no wall treatment as far as I know. That is cheap and slightly effective but it won't sound like a proper accoustic treatment.

The speaker itself is obviously important but the acoustic environment in the auditorium is what makes a theatre sound great. A great speaker in a lousy room will still give you lousy sound.

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

Posts: 3629
From: Dallas, TX
Registered: Nov 2000


 - posted 09-03-2003 11:17 PM      Profile for Adam Martin   Author's Homepage   Email Adam Martin       Edit/Delete Post 
Somewhere in the Imax Basics thread, I posted photos of the PPS speakers from both the GT and SR sound systems.

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