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Author Topic: SPEAKER CUESTION Mike Moreno Expert Film Handler Posts: 200 From: culiacan sinaloa mexico Registered: Jul 2008 posted 01-14-2009 12:10 PM                        HI, IM FROM MEXICO, I HAVE A CUESTION, AND I FOUND SOME BROKEN SURROUND SPEAKERS IN ONE AUDITORIUM. WHAT CAN IT CAUSE THIS PROBLEM? HOW CAN I PREVENT THIS PROBLEMS IN THE FUTURE IN OTHER AUDITORIUMS? THANKS.  |  IP: Logged Chris Slycord Film God Posts: 2986 From: 퍼항시, 경상푹도, South Korea Registered: Mar 2007 posted 01-14-2009 12:33 PM                     Too vague. You didn't describe what was the cause of the speakers being broken and since we don't know why they're broken we can't tell you how to prevent that cause from happening again. And btw, the word is "question."  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 01-14-2009 01:33 PM                       You need to more specific. Brand of speaker would be the first thing. Brand of amplifier would be good. Then we can maybe make a guess. How do you know they are broken? Did you test each one with a meter or a battery? Everyone here is willing to help but you need to provide more information to start. Don't worry about correct spelling. Many of our best technicians can't spell at all and English is supposed to be their first language.  |  IP: Logged Chris Slycord Film God Posts: 2986 From: 퍼항시, 경상푹도, South Korea Registered: Mar 2007 posted 01-14-2009 10:51 PM                     quote: Sam D. Chavez Don't worry about correct spelling. Many of our best technicians can't spell at all and English is supposed to be their first language. I concur. It's like yesterday my pathology teacher, who is an MD originally from Taiwan, at one point had someone not understand what he said (because they weren't listening closely) and he said "I wish my English was better." I was left thinking "You speak better than many Americans." And to the OP: I wasn't judging you on the spelling, just giving him a reminder since English is so weird with vocabulary and grammar.  |  IP: Logged Mike Blakesley Film God Posts: 12767 From: Forsyth, Montana Registered: Jun 99 posted 01-15-2009 09:57 AM                        Yes, at least he's not having trouble with his "rectifryers."  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 01-15-2009 01:32 PM                     quote: Yes, at least he's not having trouble with his "rectifryers." [Big Grin] LOL....  |  IP: Logged James Westbrook Phenomenal Film Handler Posts: 1133 From: Lubbock, Texas, Usa Registered: Mar 2006 posted 01-15-2009 01:53 PM                     Sometimes "rectiFRYer is correct, depending on the equipment...  |  IP: Logged Jonathan Bodge Film Handler Posts: 83 From: East Dorset, VT Registered: Nov 2006 posted 01-15-2009 05:05 PM                     I've seen, believe it or not, mice do damage to speakers. I think you got mice.  |  IP: Logged Andrew Bangs Expert Film Handler Posts: 148 From: Kerrville, Texas, United States Registered: Sep 2008 posted 01-16-2009 01:38 AM                        I hear bad speakers or blown speakers and my first thought is someone wanted it loud and went to loud. If you crank the wrong thing up it is real easy to blow out speakers. You need to get new speakers in and have a professional set the levels and Equalize the room then only ever make small adjustments to your processor and never touch the amps. P.S. I did mean "rectiFRYER" as it was toast.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 01-21-2009 09:54 PM                     What can cause this problem - I've seen surrounds where somebody stood on a seat back and punched out the speakers. Probably you would recognize this problem though. Presumably the speakers are actually "blown". Speakers "blow" when they are overloaded, given more power than they can handle. If the system is designed correctly that rarely happens - but systems get designed incorrectly all the time. Analog sound can only put a limited amount of sound into the surround speakers and there's always a bit of crosstalk between screen and surround speakers. This has two effects: you don't need speakers capable of high sound pressure and the associated high power amplifiers, and there's almost always some sound audible from the surround speakers during a film. Digital sound is quite different in how it provides surround sound. There's a full range discrete digital channel feeding the surround left and right (and maybe rear) channels. The sound mixer can route very loud sound to the surrounds for as long as he likes with no crosstalk into the screen channels. Converting an analog sound auditorium to digital sound requires upgrading the surround speakers and amplifiers - or you will have blown speakers and/or amplifiers. Another issue with digital is that the surround channels are totally silent when the sound mixer has not put sound there. Many people assume the surrounds are not working or turned down when experiencing digital sound for the first time. Many films use surround for subtle sounds to invoke a sense of space. It is too common for projectionists or managers to turn up the surround channels in the mistaken belief that they are somehow "too low". When a film that has loud surround effects comes in, speakers get destroyed. An underpowered amplifier can blow speakers as well. When transistor amps overload, they usually "clip" which flattens the peaks of the output waveform. This creates a LOT of high frequency power from signal distortion, and will burn out the HF (tweeter) drivers in a short time. Speakers with blown tweeters suggest underpowered amplifiers. If the speakers and amplifiers seem to be sufficient for the auditorium, defective amplifiers can damage speakers as well. A transistor amp can supply DC power to the output - either a lot with no actual sound or a little with no apparent sound problem. DC power makes no sound but heats up the LF (woofer) speaker voice coils. Overheating usually causes the coil to detach from the driver cylinder and it makes a horrid sound for a while before breaking completely. Such problems suggest amplifier trouble. Just plain too much good audio signal can cause both tweeter and woofer failure identical to that from amplifier problems. Check that the speaker power handling capacity is roughly equal to the amplifier output power - 8 100 watt speakers on a surround channel should have an amp rated around 800 watts. Be wary of any non-professional equipment - the power ratings for "home" or "home theatre" stuff are mostly imagination. When a JBL or other reputable pro speaker says it's capable of handling a continuous 100W of "band limited pink noise" you can assume that if you fed it a continuous 100W of "band limited pink noise" it would handle it much longer than you can stand the racket. Try that with a home speaker rated for 100W and you'll probably have a blown speaker in a few minutes. Amplifier ratings are the same. Cinema amps may not put out full rated power "forever" but should definitely do it for tens of minutes before overheating and needing a rest (cinema amps are often made to handle the typical power load profile of cinema sound, ie mostly fairly quiet with some quite loud stuff). Home stuff is often rated according to bizarre standards... often with power ratings five or ten times what a professional amp with exactly the same capability would be rated. I've seen a "ghetto blaster" labelled "1800 WATTS!!!!" but with a 2 amp line fuse (we have 120V power here)...  |  IP: Logged Bastiaan Fleerkate Film Handler Posts: 85 From: Linschoten, Utrecht, The Netherlands Registered: Jun 2006 posted 01-23-2009 12:21 PM                        There maybe something wrong with the wiring in the theater. I've blown up a subwoofer when I turned on the power in the projection booth... ( But then we got a better subwoofer back ) I've also heard some cracks and loud noises in some theaters, when the xenon ignites... OR you were watching a movie with the volume way to high.  |  IP: Logged Mike Moreno Expert Film Handler Posts: 200 From: culiacan sinaloa mexico Registered: Jul 2008 posted 01-23-2009 03:30 PM                        I FOUND THIS PROBLEM JUST BY CHECKING ALL THE CHANNELS IN THE AUDITORIUM WITH THE PINK NOISE ROTATION FROM A DOLBY 650 PROCESOR. i took a surround speaker and y use a meter and it doesnt read the 8 ohm it should read. the other thing i found was in the amplifer output, when i plug the speaker in the output i can see sparks. and when the movie is running the amp clip. the surrounds are SLS model cs653s and the amps are crown xls602. one amp for the left and rigth surround, each chanel has 4 speakers.  |  IP: Logged Todd McCracken Master Film Handler Posts: 263 From: Northridge, CA, USA Registered: Mar 2008 posted 01-23-2009 04:45 PM                    Glad to see you got that pesky cap lock problem under control. If you are getting sparks I would say that you have a rather serious short somewhere (this would explain the amp clipping out too)  |  IP: Logged Mike Moreno Expert Film Handler Posts: 200 From: culiacan sinaloa mexico Registered: Jul 2008 posted 01-23-2009 05:49 PM                        THANKS EVERYBODY  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 01-24-2009 07:42 AM                        8 ohm reading on speakers assumes you are using 1000 Hz as a test signal. The DC reading will usually be much less. Louis  |  IP: Logged

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