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General Asylum General audio topics that don't fit into specific categories. |
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General Asylum General audio topics that don't fit into specific categories. |
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In Reply to: Re: Your problem is safety. posted by Aylwin C on April 1, 2007 at 22:06:52:
and try running the system from a grounded kitchen outlet. Also, investigate whether the fixtures in the music room have a ground inside: if the wiring is armored cable, the cable jacket may be grounded even though the fixture only has two terminals. There might be a way to legally install a grounded outlet without having to rewire the house.My guess is that you have a faulty piece of equipment, which could include a cable. The extension cord experiment will rule out a grounding issue as part of the trouble-shooting procedure.
To locate the cause of the hum, start with the power amp connected to the speakers. Unplug the interconnect cables at the power amp and turn it on. If you hear no hum, then turn off the amp and plug the interconnect cables back in to it. Unplug them from the line stage (or whatever drives the power amp) and repeat the experiment. Keep doing this as you work your way upstream, adding one stage at a time. The hum will appear when you plug in the defective component. Always turn the power amp off before making any changes.
You may get a false positive result if the interconnect cables are not shielded and not terminated. It will help to make up some dummy terminations from mating jacks and 50 to 100 ohm resistors, to plug the input ends of interconnect cables into. Most source components have about 50 to 100 ohms output impedance, and this loads the cables at the source ends. By leaving them floating, they may pick up hum that you normally would not hear.
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Follow Ups
- Get a heavy extension cord, - Al Sekela 11:16:47 04/02/07 (2)
- Great advice! Thanks! - Aylwin C 09:13:14 04/03/07 (1)
- I'm glad you were able to make progress! - Al Sekela 17:35:32 04/03/07 (0)
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