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Author Topic: Sound Advice Jonathan Bodge Film Handler Posts: 83 From: East Dorset, VT Registered: Nov 2006 posted 03-05-2012 08:38 PM                     I need some sound advice, which could be interpreted 2 ways...story...local board of directors type stage theater (with concave ceiling dome to match)...old dolby processor (20 yrs.) JBL speakers behind screen. Reverse scan. Yamaha amps. Needs upgrading for sure. "Know it all" wants to replace behind screen JBLs with small QSC speakers up front of the screen. JBL's referred to as "old school". Reason for bringing speakers up front, so they can have dual use. Live and video/film. (not how I would design it.) So, would a USL processor be good for both 35 and a top of the line blue ray? Are the Old School JBL's adequate for the digital realm? For a bi amped system in a 500 seat theater what amp power might be good? Thanks all..  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-05-2012 08:49 PM                        There are no new "rules" in audio, so old school, if adequate, will still be good. Certainly JBL had its share of dogs (need model number). Yamaha to me is questionable. Is Dolby Digital a requirement? If so, use cp650, if not, perhaps an Ultra is enough. As a general rule, the speakers in front of the screen is good for stage and behind the screen for film. That is why few, if any, systems are interconnected. I would encourage a gentle upgrade of film and a seperate system for live. That way the "know-it-all" can win, too. (btw: the film system will always sound more full, and more powerful.) Louis  |  IP: Logged Jack Theakston Master Film Handler Posts: 411 From: New York, USA Registered: Sep 2007 posted 03-06-2012 01:22 PM                     I agree with Louis. Set up two systems, and tell the tech to stick his nose in his own business.  |  IP: Logged Martin McCaffery Film God Posts: 2481 From: Montgomery, AL Registered: Jun 99 posted 03-06-2012 02:17 PM                        Louis and Jack are, of course, correct. Having watched other theatres deal with this over the years you should go to your stage tech guy and/or board with information and documentation about how stage sound is different than movie sound and each requires its own system to be done perfectly. So many people think sound is sound (and movies are magic). Education is the key to getting your place equipped properly. And it is best to try to do it without internal warfare.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-06-2012 09:04 PM                        Besides, proper film systems are always of higher quality; the entire reality MUST BE serviced through the audio. Stage systems only need be good enough for mikes. The difference between: voices and A-bomb blasts. Louis  |  IP: Logged David Buckley Jedi Master Film Handler Posts: 525 From: Oxford, N. Canterbury, New Zealand Registered: Aug 2004 posted 03-07-2012 03:13 AM                        If "small QSC speakers" will do the job of the live usage, then either the venue is quite small, or the live needs are quite limited, or both. All things being equal, separate systems is the recommended approach. If nothing else, it prevents the attitudinal conflicts that can arise between movie sound people and live sound people, as demonstrated above. The two worlds have different requirements and value different priorities, and there are even some valid reasons why the approaches taken with cinema and live sound reinforcement are different. Of course, if you need one system to deliver digital movie audio, live theatre and musicals, Metallica and dubstep (all at their intended volume, scope and scale), and to sound good with all these types of programme material, then you have a different set of problems to solve, and small box of any type wont be the answer  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 03-07-2012 08:16 AM                        I'm not a sound expert, but I know what sounds good. The limiting factor with this type of venue is often the room, from what I have seen (heard). Large, old theatres can usually be made to sound good for live music and performances or film reproduction, but usually not both. A "live" (reverberant) room is preferred for live music, while a "dead" room is preferred for film. Rooms that were designed and built before the advent of talking pictures seem to be especially live. I don't have a solution, but I can point to at least one example of a building where the overall sound quality was better with a single A4 behind the screen than with a full-blown modern sound system (installed for a rental and then removed). One change that did make a difference with the multichannel ssytem was increasing the center channel gain by 2-3 dB over the left and right stage channels. Dolby might not approve, but it worked. As an audience member, the most important issue is dialogue intelligibility. The second most important issue for me is having the sound come from behind the screen, rather than from above it or from the sides. Get these right and everything else should be fine. Get them wrong and nothing else matters. I agree with the comments that live sound people do not understand film sound (for the most part), although they do have some interesting tools now that might be useful for improving sound in problematic venues (in particular, DSP-based room correction and time alignment systems).  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-07-2012 12:28 PM                        Scott: besides increasing center level; it is also possible to "tailor the response" only on center. Set up normally on all three screen channels, add 4-5 db to center channel, then switch off all channels except center. Using a film with dialog, and foreign accents, roll off the low bass, allow a rise in hf at 3-5k, and then roll off normally above. You may then have to raise the level again, a little.u  |  IP: Logged David Buckley Jedi Master Film Handler Posts: 525 From: Oxford, N. Canterbury, New Zealand Registered: Aug 2004 posted 03-07-2012 03:42 PM                        quote: Scott Norwood As an audience member, the most important issue is dialogue intelligibility Absolutely. And it is this that leads to the one substantive difference between speaker systems used for cinema and those not used for cinema. Cinema sound systems generally always have a horn for MF (and sometimes another horn for HF), but the MF horn of a cinema speaker has a downwardly extended frequency response compared to their live sound brethren. Often the horn will go down to somewhere between 200 - 300Hz and extend beyond 3K. In live sound it is unusual to have a single driver that covers that range. The upshot of this is that speech is reproduced by just the MF horn, a single speaker element, and thus there are no phase or timing issues that can occur when there are two or more elements reproducing speech. This gives the average cinema sound system a big advantage over an average live sound system for speech reproduction in terms of intelligibility. As the live sound system quality (and thus the cost) improves, the issue becomes much less pronounced, as there are more expensive ways to skin the cat. But it's only in the last decade or so that this has been then case; the single MF horn has done the better job for the goodly end of a century.  |  IP: Logged Daniel Schulz Master Film Handler Posts: 387 From: Los Angeles, CA USA Registered: Sep 2003 posted 03-09-2012 01:35 PM                        It's worth mentioning here the Datasat AP20 as well. The AP20 is a 16 channel processor with EQ memory presets - so you could EQ the room for movie exhibition, save those settings, and then do a separate EQ for live music, video games, etc. It also incorporates Dirac Live room optimization (think Audyssey, but for professional environments rather than living rooms), which can help significantly with challenging room acoustics. For alt content (such as DVDs or Blu Rays) it will decode AC3 and the full suite of DTS codecs, and with an optional film card can handle 35mm optical tracks.  |  IP: Logged F. Hudson Miller Film Handler Posts: 48 From: Los Angeles, CA, USA Registered: Jun 2009 posted 06-09-2012 11:52 AM                  Way too many variables to be a DYI project. Hire a good theater sound company and listen to 6 or 7 of their installations. Money extremely well spent. Nothing worse than bad theater sound. Get it right and it will last for years (with minor updating); get it wrong and you will be replacing it over and over. Penny wise and Pound foolish is not the way to go. Good luck.  |  IP: Logged F. Hudson Miller Film Handler Posts: 48 From: Los Angeles, CA, USA Registered: Jun 2009 posted 06-09-2012 02:02 PM                  Also remember that films are all mixed through a perf screen, and that if you are running the track without a perf screen you need to compensate in the B path. Like-wise, when you run a Blu-ray or DVD through a perf screen you need to compensate that because the source was usually remixed near field for consumer release.  |  IP: Logged Chuck McGregor Film Handler Posts: 47 From: Bremen, ME, USA Registered: Mar 2012 posted 06-11-2012 04:56 AM                     quote: Louis Bornwasser said: Besides, proper film systems are always of higher quality; The difference between: voices and A-bomb blasts. Sorry to jump in late on this... Louis, with all due respect, this statement is not true by any stretch. "Proper" PA systems can easily match "proper" film systems. They both have to deal with the same 20 Hz to 20 kHz spectrum and dynamics. Reproducing dialog, "A-bomb blasts," or violins knows no favorites in terms of doing it with high quality. In fact, I would bet the best PA technology (loudspeakers) I know of against the best cinema technology. The ultimate criterion for loudspeaker sound quality is transparency = lack of coloration = pristine transient response. This can be measured and is done so with the best PA equipment. I've never seen such data for cinema systems (except for the one I've been working with.) And no, the bode plots, impulse responses, waterfall plots, ETC's et al from typical commercial measurement systems don't have the adequate time and frequency resolutions to do this. RTA measurements are even further down the list. I didn't detail this in my Yak "Who the Heck..." profile, but part of my career was some dozen years being in charge of the acoustic measurement labs, measurement data processing, and generating the product specifications for both Community Professional Loudspeakers and Eastern Acoustic Works (EAW). As such, I do have a little bit of knowledge about loudspeaker sound quality and measurements of same. As to the primary question in this thread, a well-qualified audio consultant and separate PA and cinema systems are the right pieces of advice. Quality usually has a price. Filet mingnon costs more than a shank cut  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 06-11-2012 12:13 PM                        Usually the "budget" causes P.A. and film to want to be combined. Clearly your kind of P.A. is vastly superior to the 2-15's and a horn flying above the stage, which is what they want the movie to come out of (to save money.) There are actually 2 problems: Lack of quality in cheap P.A. The speakers are not located in the right place for both uses. If amps are to be common, then the additional switching and eq's need for each eat up the money "saved." L:ouis  |  IP: Logged Chuck McGregor Film Handler Posts: 47 From: Bremen, ME, USA Registered: Mar 2012 posted 06-11-2012 01:03 PM                     quote: Louis Bornwasser Usually the "budget" causes P.A. and film to want to be combined. Too bad there aren't really cheap projectors available to compliment such a budget-friendly approach (combined film/cinema audio). Then "they" could save even more money by having lousy sound AND a lousy image  |  IP: Logged

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