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Author Topic: cinema sound design Mike Moreno Expert Film Handler Posts: 200 From: culiacan sinaloa mexico Registered: Jul 2008 posted 03-25-2009 08:58 PM                        i wonder if there is a web site where i can learn how to design a cinema sound system, like what kind of speakers or amplifiers i have to use for front speakers, the power of the amps, the ohms of the speakers i have to consider.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 03-25-2009 09:15 PM                        I've been looking for this for years. There are a couple of Dolby publications from the 1980s and early 1990s that have some good guidelines, as well as the THX documentation, but I haven't found anything resembling a complete guide to specifying a modern cinema sound system. I'm still not entirely clear on why systems with similar equipment and room shape/size can sound so different. I'd also be interested in reading about modern systems that have been installed in older-style (single-screen with balcony) houses and why some of these systems completely suck and others sound amazing. The best sound that I have ever heard in a theatre was in February, 2000 in the Cinerama Dome in LA (now the Arclight), from about 1/3 of the way back from the screen and almost dead center. Someone please tell me how to make every theatre sound like that.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 03-25-2009 09:46 PM                     quote: Mike Moreno the ohms of the speakers i have to consider. ..and what kind of wire to use and gauge. 14g 25 plus strand since it requires low voltage to run speakers. If you're gonna get crazy with high power behind the screen, then think on 12g stranded runs esp on subwoofers. Surrounds, twisted 14/2 pair helps. ..and behind screen, you always have at least two extra runs just in case a run opens up, you got a spare right there to replace.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-25-2009 09:56 PM                     quote: Scott Norwood Someone please tell me how to make every theatre sound like that. Seems to me those were the original Altec A-2's back then. There were originally A-2's installed in the Dome when it opened. The best sound I've heard in Hollywood was at the large mix stage at Todd-AO which is no longer in existance. Mark  |  IP: Logged Bobby Henderson "Ask me about Trajan." Posts: 10973 From: Lawton, OK, USA Registered: Apr 2001 posted 03-25-2009 10:05 PM                     There seems to be many more variables to good movie theater sound than the shape of the room and the sound system hardware installed in it. Although I'm fairly convinced standard sloped theaters have better acoustics than stadium seated theaters. The building's construction (type of materials used for the walls, ceiling, etc.) play a big part. It would be interesting to know what materials were used in building the Cinerama Dome auditorium, as well as what kinds of acoustical wall treatment, baffles, etc. were installed.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 03-25-2009 10:33 PM                       Dolby School served this purpose for many years. It wasn't that Dolby dictated the spec's but the seminars were in part an exchange of ideas and Dolby usually identified hardware and ideas centered on that worked specifically for this application. Tom Holman of THX had a lot to do with advancing the art when he was there. The THX spec's were an enhancement to the Dolby guidelines and are still relevant today.  |  IP: Logged Andy Frodsham Expert Film Handler Posts: 238 From: Stoke on Trent, Staffs, UK Registered: Nov 2006 posted 03-26-2009 02:52 AM                     I'd like to know how good a well specified system should sound? Against what criteria should one judge it from a subjective point of view? I know this all sounds rather vague, but I don't know anymore what I am listening for! Trying to compare the sound in my theatre to a well matched home hi-fi system does not seem particularly fair - but why not? Doing a fairly straight comparison, shouldn't a CD played at home sound about the same when played through the theatre's non-sync? I know it is harder to judge soundtrack material. I am talking about subjective evaluation here (I spent some time working in a Hi-Fi shop when I was younger and have a fairly well-trained ear) not frequency response specifications etc.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-26-2009 08:23 AM                     Monte...where do you get your rules of thumb?...with wire gauge, it is all about the current, not the voltage. So lets say you are driving a single 8-ohm sub to 800-watts (not very much in the subwoofer world)...do the math...that is 10-amps on that cable. If you were an electrican, depending on the run and the fill in the pipe, you'd say you need 14awg. The problem is, you are not running 800-watts to a sub in most theatres...you are running much more and often paralleling them up. In-line resistance is also the enemy of bass as it kills the damping of the system. For subs...think in terms of 8awg for the long runs. The same rules apply to the other speakers too. Look not only at the current on the cable but how that cable's resistance over the run compares to the driving load...it shouldn't be anywhere near (beyond a factor of 10) or you are compromising the system. The room is the most difficult aspect of getting good sound, for me. Often, that deck of cards is dealt before I ever have a chance...but good sound starts with the room's design...long before the first piece of sound making equipment is ever chosen. Steve  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 03-26-2009 09:38 AM                        The "Cinema Sound System Manual" by JBL which can be found on jblpro.com under Downloads>Technical Library>Manuals answers a lot of the basic questions and is a good starting point for reading up on the subject. Of course, it doesn't answer all questions and a lot of the information given there is specific to JBL products.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-26-2009 02:18 PM                        I have send the "Guidelines for Dolby Stereo Theatres" book to architects for decades. When (if) the room is deficient, then I can show the architect which page number he failed to comprehend. It may not fix the problem, but it sure fixes the blame. All you need is in that book. Most was writtenor editted by Ioan Allen. Louis  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 03-26-2009 06:55 PM                     Thx Steve for that info. What I put in my comments is from what I've seen other installers use for their installs. They mainly run 14g for the stage, subs and surrounds (and I know one plex that ran 12g SOLID for their speaker runs..) -Monte  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-26-2009 08:11 PM                     Another misconception...Solid does not have any problem moving sound (or picture for that matter)...it isn't the best conductor to make the termination with though. Steve  |  IP: Logged Geena Phillips Expert Film Handler Posts: 198 From: Norcross, GA / USA Registered: Apr 2006 posted 03-27-2009 01:13 PM                        In this day and age, I would also recommend having a processor with optional RCA input jacks for flexibility when it comes to Non-Sync audio. Most modern processors have this capability, but if you get one that doesn't, it's not difficult to remedy.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-27-2009 05:38 PM                     I preferto have all my I/O's as balanced if possible  |  IP: Logged Eric Robinson Jedi Master Film Handler Posts: 538 From: Santa Rosa, CA Registered: Jan 2005 posted 03-27-2009 09:11 PM                     quote: Louis Bornwasser I have send the "Guidelines for Dolby Stereo Theatres" book to architects for decades. This is also located in the film-tech manuals section under. Dolby Technical Guidelines for Dolby Stereo Theaters (1994 publication) By the way, does anyone here use the Jiffy test film?  |  IP: Logged

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