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Thread: Does anyone know anything about IMAX speakers?

  1. #61
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    Bridged

    Quote Originally Posted by Woofer View Post
    John,

    The 600x is the 5B.
    ... and yes, they are a 3 channel, but two of them are bridged.

    Woof.
    Do you think it is possible to unbridge them and use them as normal 3 channel amps?

    Thanks

    John

  2. #62
    Senior Member Woofer's Avatar
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    Quote Originally Posted by mrjschmitz View Post
    Do you think it is possible to unbridge them and use them as normal 3 channel amps?

    Thanks

    John
    I just don't know, yet.....
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  3. #63
    Senior Member Woofer's Avatar
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    Two more pics of the back of the boxes showing the TAD (with the 8" removed), and crossover.



    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  4. #64
    Senior Member Woofer's Avatar
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    Here's an interesting claim, in this Altec 617-8A listing:

    http://www.gumtree.com.au/s-ad/high-...ers/1031038321

    The seller states,
    ALTEC DUPLEX 617-8A SPEAKERS by Sonics Associates Inc. for IMAX® 3D.
    .

    Does any one know if this is correct, and which year models were they used in?
    It seems a bit unlikely given that I thought the 617 wouldn't have been produced any more at the time the IMAX were made, or were they?

    Any input most appreciated.
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  5. #65
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    I am the designer of the IMAX PPS (Proportional Point Source) theater loudspeakers and associated active crossovers. I came across this thread and joined the forum to provide correct information about these speakers.

    Quote Originally Posted by Woofer View Post
    Two more pics of the back of the boxes showing the TAD (with the 8" removed), and crossover.
    The components on the PC board are for DC protection only. The crossovers were entirely active and were integral with the power amplifiers.

    The polarity "reversal" on the 8" midrange driver - which only applies to the larger version of the speaker with 4x12 LF transducers - is to account for its physical reversal: it is mounted with its magnet forward. The same transducer in the smaller version, which employed 2 12" LF transducers firing through slots - was mounted and wired conventionally.

    With the exception of the TAD 2001 HF driver, the transducers in the PPS speaker were produced for Sonics on an OEM basis by Eminence. Other than the HF driver, which was TAD only, my specifications for the design included approved transducers from three manufacturers: JBL, Cetec Gauss, and Eminence. JBL discontinued the 12" drivers in the LF section and Sonics encountered some issues with the JBL 8" driver called out for the midrange. Mark IV Audio acquired the Cetec Group, moved transducer manufacturing to an EV plant in Tennessee, and immediately began using different parts to make Gauss transducers. At that point, the only manufacturer whose parts were compliant with the specification was Eminence, so Sonics went with them. To my knowledge, those components were unchanged for the production life of the design. IMAX dissolved Sonics ca. 2002 (+/- a year or two), at which time production of the PPS system ceased. At that time, sufficient inventory of those systems had been amassed to supply new theaters for the next 3-4 years.

  6. #66
    Senior Member 1audiohack's Avatar
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    Hello Jay;

    Welcome!

    From one who is interested in large format cinema sound systems, thank you!

    All the best,
    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  7. #67
    Senior Member Woofer's Avatar
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    Hello Jay,

    .... and I'll join Barry, in offering a HUGE "WELCOME" from me too!

    Thank you so much for your most valuable input.
    As you must know, reliable source material on the IMAX boxes is pretty hard to come by even with the 'net being what it is.
    I am honoured that you (being the Designer of these magic boxes), have added your "two bob's" worth to the thread.
    There's a few of us out there now, and on behalf of all of 'em, please don't hesitate to add anything extra that comes to mind.
    .... and if there's anything else in this thread that needs correcting, don't hesitate in setting the records straight.

    George.
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  8. #68
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    A BIG welcome to Jay!

  9. #69
    Senior Member Woofer's Avatar
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    @Jay,

    What was the 'design philosophy' behind that box?
    What gave you the idea to create a composite box of that particular design?
    Were you trying to create something point source e.g. like a giant Altec 604 or a Tannoy speaker etc?
    Did it take a long time to come up with that final design?
    Sorry for all the questions. (If you were me, you'd understand.... )

    I still can't believe at how good they sound, at any level, and any distance.
    You should be proud....
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  10. #70
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    There was then and is now no single element in my design philosophy that overrides all else. Details matter. A common element in all of my designs - predating the PPS and continuing to this day - is the concept of a multiway loudspeaker that performs as a single, very well-behaved full range source. The specifics of the design of the IMAX PPS speaker - which include the horn shapes and the configuration of the LF section - were driven by a recognition that, for a multichannel sound system to be effective, the relative levels and responses of each channel as presented to any given seat need to be as well-matched as possible. Within the constraint that all six speakers had to be the same design (an argument could be made that six different designs would be ideal), we were successful in achieving that goal. The R&D process that led to the PPS design included a preliminary revision of the existing design followed by a completely new design. The initial redesign took about a year, and the all-new PPS was in production a little over two years after that.

  11. #71
    Dis Member mikebake's Avatar
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    Like.

  12. #72
    Senior Member Woofer's Avatar
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    Jay,

    Thanks heaps for the extra input.

    I have yet to see a spec sheet for ANYTHING to do with the Audio set-up for an IMAX Theatre.
    ..... and I've spent hundreds of hours looking.
    Is there one that you could possibly share? (eg: frequency response, SPL figures etc.)

    In regards to once you had designed and built what you wanted and finally installed it all in a theatre, after walking around the room, what were your first impressions, (if you can still remember back that far?), and was there a sweet-spot in the room, and more importantly where was it? (for next time I go to an IMAX theatre).

    Was there anything you weren't happy with, and took it all back to the drawing board and started again?

    Just one more thing (sorry), but how did you come up with the concept of building a separate room to put the subs in, (dimensions if you could, please), and then use the whole thing as one giant sub? That's just brilliant!

    G.

    ps: There's been just one more thing that's been confusing me..... (yes, it doesn't take much )

    HOW do the boxes get powered up?
    OK, we have the Sonics 600X (running in TWO channel mode) with the in-built cross-over and the LOW split out of the back to obviously an 800X, but that still only gives you THREE Way. If the system is FOUR Way, including the Subs, where does the 'other' (SUB) band-passed signal come from and what amp does it go to? Another 800X?
    So is there one 600X and two 800X per channel?
    (600X High and Mid, 800X Low, 800X Sub)
    Damn.... now even I'M confused.....
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  13. #73
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    IMAX never published specifications for theater acoustics or sound systems. The information was proprietary. They didn't even sell projectors or sound systems: they only leased those items.

    There was never any doubt of the results we would achieve in the development process that led to the PPS loudspeaker design. We did enough advance analysis and testing - both in laboratory and in theater environments - to ensure that there were no surprises. The results were as expected.

    As for a "sweet spot," projection quality is more definitive of that than sound quality. When you sit in extreme left or right positions - especially in the front rows - there is inevitably distortion of the image. For that reason, I suggest selection a central seating position - possibly just rearward of the center rows of seats - for the best visual experience. BTW, this applies to all movie formats, not just to IMAX.

    The subbass array is driven from a completely separate signal chain than the channel signals. First, each channel signal is routed through highpass and lowpass filters. The highpass outputs are sent to their respective speakers. The lowpass outputs are mixed and send to the subbass amp racks. You will need another amp and additional filtering to drive a subwoofer, but the bandwidth of the main speaker is enough that subbass won't really be necessary in a residential sound system.

  14. #74
    Senior Member Woofer's Avatar
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    Quote Originally Posted by Jay Mitchell View Post
    The subbass array is driven from a completely separate signal chain than the channel signals.
    .... and THAT'S the very bit of key info I was looking for Jay.

    So that means, you have ONE 600x for the highs, and the mids, (utilising the internal x-over), then link out of that 600x to an 800x for one pair of 12", then link out of that 800x to ANOTHER 800x for the 'other' pair of 12", and so powering just the ONE box, right?
    One box = 1x 600x, 2x 800x.
    Then you run another 800x for the Sub, but fed from a separate filtered feed.
    I just knew there had to be another x-over (of sorts) involved....

    Thanx heaps.....
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  15. #75
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    Hi Jay:

    First, thanks for contributing. Interesting design. Second, are you still with IMAX? Is there anything you can disclose about your current designs?

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