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Author Topic: Strange noise on front speakers Thomas Pitt Master Film Handler Posts: 266 From: Leeds, West Yorkshire, UK Registered: May 2007 posted 01-01-2008 05:42 PM                     The last two times I've been in Cineworld Bradford auditorium 4, I've noticed a strange noise coming from the front speakers. The noise is hard to describe; somewhere between a hiss and a buzz. The closest thing I can think of is if you have an FM radio next to your computer. If the FM station it's tuned into is currently silent, you might pick up a slight buzzing from the computer's interference. The noise is not very loud (compared to the normal volume they run movies at), but it is noticeable during the intermission when no sound is playing. The noise level never changes; it's always constant. The noise is also there while the film is running, but you can only really hear it during silent parts of the movie. When there's lots of film sound, it drowns out the noise - there's no reduction in quality that I can hear. The fact that the noise remains during intermission, whether silent or with non-sync music, seems to suggest one of the amplifier units is at fault. Is it possible that the amplifier is picking up some noise from a nearby conduit or other piece of equipment? Could a component in the amplifier have failed?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-01-2008 05:46 PM                     I would call the latter since you say that it's constant with N/S and with movie audio...amp's getting tired, loose ground connections or caps inside drying out .. - Monte  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 01-02-2008 01:40 PM                     Sounds like it is a grounding issue. As you and Monte suggest, it could be a bad amp. It could also be due to a poor wiring job in the sound rack. I have run across many theaters that have had hums/buzzes like that, and it turned out to be improper wiring (negatives not connected, no sheilds!) from the processor output to the amplifier inputs. Rewiring eliminated the problem.  |  IP: Logged Christopher Howland Film Handler Posts: 9 From: Mashpee, MA, USA Registered: Jul 2007 posted 01-02-2008 03:45 PM                     I had the exact same problem, i thought either the amplifier was going or there was a ground loop problem in the wiring or something. However, i was fiddling around in the booth, and saw the FM transmitter for the hearing devices sitting on the back of the amplifier rack!! I moved it away, and it immidiately solved the problem. The amps must not be shielded well enough or something.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-02-2008 09:21 PM                     It would be a good idea if you posted the amp make processor make and model and monitor type  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 01-03-2008 02:11 AM                     Or perhaps you are in one of those situations where you have power cables running along speaker. On the other hand, light dimmers often are a source of humming/buzzing/noise in speakers. Demetris  |  IP: Logged David Graham Rose Expert Film Handler Posts: 187 From: Cambridge, UK Registered: Sep 2002 posted 01-03-2008 12:55 PM                     Greetigs All They're Ashly FTX-2001, Ashly crossovers, CP650 with BTS MS-X monitor. However, it's most likely to be the transformers for the neons on the outside of the building. Some cinemas site them here behind the screen, particularly if the screen is on an outside wall with signage on them. Very confusing at times, especially if you don't know they're there! Regards David  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 01-03-2008 01:08 PM                        Try unplugging the amplifier inputs to see if you are then "clean." If you are, then your problem is between the Dolby and the amps. That amp & processor can be fussy at times, but, I assure you, it can also be tamed. Some monitors (that have a way to listen before and after the power amp) can be touchy because problems on the speaker lines can be coupled back to an earlier stage. If you suspect this, unplug the "processor out" cables on the monitor and run just the speaker out for awhile. Louis  |  IP: Logged Jonathan Wood Expert Film Handler Posts: 206 From: Oxfordshire, United kingdom Registered: Jan 2008 posted 01-05-2008 11:03 AM                     I've heard that some auditoriums play a level of white noise to help cancel out noise from adjoining theatres,(or am I going mad and just dreamt this?!)? I've heard similar sounds myself and since they where from the surrounds, assumed they where for noise cancellation.  |  IP: Logged James Westbrook Phenomenal Film Handler Posts: 1133 From: Lubbock, Texas, Usa Registered: Mar 2006 posted 01-05-2008 11:40 AM                     No, Jonathan... There is a pink noise generator used for testing purposes by the technicians but these are processor cards they carry with them, not permanently installed in the processor. There should be no buzz in the sound at all. Often the sound in the auditorium itself would drown out any sound leaking from nearby auditoriums. Accoustics and sound dampening is what is used to combat sound leakage from auditoriums. This is a Construction issue, not a sound system issue.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 01-06-2008 04:53 PM                        Back "in the day:" sometimes air handler noise WAS used to mask sound coming through walls. Other times it was unplanned. I've only done that once, later slowing down the air since the walls were "good enough." Louis  |  IP: Logged Justin Gorka Expert Film Handler Posts: 174 From: High Wycombe, England Registered: Apr 2006 posted 01-08-2008 06:14 AM                     We had a similar problem in Swindon. It was something to do with the Deaf loop (induction loop). When it was unplugged the noise went away. No cure was found so it was decided not to have the loop in that screen.  |  IP: Logged Dick Vaughan Phenomenal Film Handler Posts: 1032 From: Bradford, West Yorkshire, UK Registered: Jul 2000 posted 01-08-2008 07:27 AM                        I have noticed similar problems in a number of Cineworld sites. This is made more noticeable by the lack of walk in music  |  IP: Logged Michael Brown Phenomenal Film Handler Posts: 1522 From: Bradford, England Registered: May 2001 posted 01-11-2008 04:20 PM                     The only thing i've noticed recently at this Cineworld site is how badly the volume of the SR and SRD is matched. The last film I watched in screen 4 was 'Broken Aces', everytime it defaulted into SR the volume dropped dramatically and all the audio shifted into the front left channel only. Were-as screen 16 is the other way around: The SRD is ok, but if it dropps into SR, be prepaired to have all the ear wax and cobwebbs blown out of your ears.  |  IP: Logged Eric Robinson Jedi Master Film Handler Posts: 538 From: Santa Rosa, CA Registered: Jan 2005 posted 01-17-2008 01:46 AM                     I second that... quote: Louis Bornwasser Try unplugging the amplifier inputs to see if you are then "clean." If you are, then your problem is between the Dolby and the amps. That amp & processor can be fussy at times, but, I assure you, it can also be tamed.  |  IP: Logged

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