LOUD BANGS FROM SPEAKERS DUE TO PROJECTOR SCREEN OR PROJECTOR

P

Potemkin22

Audiophyte
Hi,
Really need peoples help if possible. I am not massively technical but i will do my best to explain what is going on. I work for and AV installation company doing the admin :). But we have two issues currently. Both scenarios involve a 100v PA system with speakers (good quality kit)

First Scenario:
Two electric screens that when the remote is used to lower and raise the screens, when the screens stop a massive large audio bang can be heard from the speakers. The audio from the projector is fed back via screened audio cable to the PA, But we have done this 100 of times with no problems.

Second Scenario:

One electric screen and 1 projector (Benq) - this one is a bit weird, so when you press the button the projector remote to take it off standby, you then get three loud bangs from the speakers. The only link i can see between both scenarios is that the controller for the screen and the projector are both IR.

I would welcome anyone`s thoughts on this as we are a bit stuck currently.

Thanks All

Neil
 
highfigh

highfigh

Audioholic Overlord
Hi,
Really need peoples help if possible. I am not massively technical but i will do my best to explain what is going on. I work for and AV installation company doing the admin :). But we have two issues currently. Both scenarios involve a 100v PA system with speakers (good quality kit)

First Scenario:
Two electric screens that when the remote is used to lower and raise the screens, when the screens stop a massive large audio bang can be heard from the speakers. The audio from the projector is fed back via screened audio cable to the PA, But we have done this 100 of times with no problems.

Second Scenario:

One electric screen and 1 projector (Benq) - this one is a bit weird, so when you press the button the projector remote to take it off standby, you then get three loud bangs from the speakers. The only link i can see between both scenarios is that the controller for the screen and the projector are both IR.

I would welcome anyone`s thoughts on this as we are a bit stuck currently.

Thanks All

Neil
List the manufacturers and models of the equipment- it will help.

What is the distance between the audio cabling to the controller and power cabling for the screens? This seems similar to the situation I had with a 70V system- the various cables were more or less woven and high voltage cables were next to low voltage cables- a loud snapping sound was heard at random times. It was reduced when we separated the cables, but never stopped completely. Afterward, I was told that a filter was available.

If the screens use relays, make sure they have a way of suppressing voltage spikes. AC-operated motors often use capacitors to start and if these are old/damaged/inferior, they may allow this to happen.

You turned the amplifiers off as a way to determine that the sound is coming through the speakers, right?
 

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