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Home audio & video: constant humming sound
constant humming sound
by nick_nowak - 10/18/09 1:06 PMThis is actually an audio problem I have in my classroom. We have vcr/dvd combos connected across the classroom to a data projector that's installed in our ceilings. They are connected by audio/video jacks. (the white, red, and yellow plugs). This cord must be at least 25 feet long and runs through the ceiling. From there we have another very long auxilary cord that plugs into the "audio out" of the projector, up through the ceiling, and into the backs of our computers. Our computers, then, have stand alone speakers. When this is hooked up in this fashion, the speakers have a constant humming that drives us all crazy. I'm wondering what could cause this humming. Is there a way to filter it? Could this feedback happen because the audio/video cords are running parallel to, or across another type of cord/wire up in the ceiling?
This is happening in every classroom in our building and thoughout the district. Any ideas anyone might have would be very helpful!
This is when I reach for Audio Baluns
by R. Proffitt
- 10/18/09 1:33 PM
In reply to: constant humming sound by nick_nowak
Not an offer to write a paper on decoupling or what Audio Baluns do but these are want I use to decouple the connection for a test.
http://www.4electronicwarehouse.com/c/audio-balun as one example you should find these all over the world for "Placing A/V Devices Extended Distances from their A/V Source".
Bob
Could be a ground loop.
by jcrobso - 10/19/09 1:06 PM In reply to: This is when I reach for Audio Baluns by R. Proffitt
Google ground loops, lots of info.
The balun would eliminate ground loops.
Many causes for huming inputs
by mjd420nova - 10/18/09 5:27 PM In reply to: constant humming sound by nick_nowakFirst you have to isolate which of the inputs is introducing the hum. During what function it is present and then which input. Keeping any audio inputs away from power cables and lighting fixtures, especially flouresent lamps is important. It may be too late, but a rewiring may be required to eliminate the hum.
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