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speaker hum


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2 replies to this topic

#1 of 3 OFFLINE   steve_mr

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Posted November 27 2003 - 12:09 AM

just finished our HT and have a slight challenge. I have a Lutron Grafik Eye. Seems that when the lights are turned on, I hear a hum from the speakers. As soon as the lights are turned off, the hum stops. I seem to remember that the electrician did not connect the ground wire from the Grafik Eye to the ground wires coming in from the light fixtures. Could this be causing the problem? Appreciate any feedback.

#2 of 3 OFFLINE   DavidLW

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Posted November 27 2003 - 02:28 AM

Not quite the same problem but may be related. When I first set up by X1 front projecter, I had horizontal lines that drifted up the screen whenever I had the dining room light dimmer in a dim mode. The lines would go away whenever the dimmer was off or in the full bright position. It's just a standard light dimmer. I read elsewhere in this forum that dimmers emits EMF (electrical magnetic force) that can be picked by long cable run or poor shielding. At the time I was using descent cables (S-VHS) but it was over 35 feet long. The problem went away when I moved my DVD closer to the projector and switched to a 15 feet run. I don't know exactly what a Lutron Grafik Eye is or does but it's probablly emitting EMF or RF and one of your cable is acting like an antennae and pick it up. Phono cartridges and tape deck heads are also great in picking up EMF and RF. I don't believe you have an electrical grounding problem or the hum would show up even with the lights off. Proper grounding of audio and video equipment is a science in itself. Some one else here can probablly explain the process better than me.

#3 of 3 OFFLINE   Wayne A. Pflughaupt

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Posted November 27 2003 - 02:43 AM

Perhaps, but I doubt it. Light dimmers are notorious for polluting electrical with EMI. Typically you have to make sure all audio equipment and lighting are not only on separate dedicated circuits, but also on opposite phases at the service panel. In many cases, the dimmers just have to be replaced with higher-quality, quieter ones. That said, it can’t hurt to tie in those ground wires - maybe you’ll get lucky. Regards, Wayne A. Pflughaupt
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