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Ground Loop Issue


Peter P.

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I get a hum caused by my A250 Subwoofer amps.  They have 3-prong AC plugs.  Originally, with an Acurus ACT-3, the hum/buzz only showed up only with my DVD player that used a coaxial digital connection and unplugging it shipped the buzz.  After a tedious series of trials, I found also unplugging the A250s also stopped it.  Final solution?  Two ground plug adapters (cheater plug), one on each A250. 

 

220px-Cheater_plug_edited.jpg

 

The same buzz also occurs with my Integra DHC-80.1, also solved by the adapters. 

 

The obvious cause may not be the actual cause.  Have you tried reversing the AC plug for the tuner? 

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Are all of the units plugged into the same power strip or surge protector ?

 

Is the tuner on top of another piece of gear ?

 

How close is the antennae to anything else ?

 

Get some long RCA cables and try moving the tuner around with the ears on it.

 

Try moving the power cord around, the wires wear and break and cause hum and other noise, better to try it on cheapo speakers at low volume, pick up a pair at goodwill or craigslist if you don't have some.

 

Try running the tuner into a different system on a table top with your cheapo test speakers and see what happens. If you still have humm the problem is the tuner.

 

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Here is the solution to my problem.

 

It was the radio station.

 

Listening to other stations, with just the DJ speaking, I could not hear any hum.

 

I'm an FCC licensed Motorola technician, so I have at my disposal a service monitor capable of generating FM. I brought it inside and generated an unmodulated carrier over the air at the station's frequency, for a full quieting signal. No hum. Then I tried generating an unused FM frequency in my area at full quieting, and reduced the signal level until white noise overcame the signal. Still no hum.

 

I sent an e-mail to the station telling them what I heard, just as an FYI. I've seen problems with a ground wire on the mic which needs to be cut, or nearby sources such as a cellphone on the desktop, the cellphone charger nearby, or  nearby laptop computer/charger similarly causing problems.

 

Thanks for all the suggestions; at least it's not my equipment!

 

 

Service Monitor - 1.jpg

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9 hours ago, Thaddeus Smith said:

Ya. You're like my HAM father in law who goes around with a handheld antenna identifying all of the power poles/lines in the area which cause interference with his towers. He makes a list and then sends letters to the appropriate power provider responsible for that infrastructure.

No, please; I'm too young to be a HAM! 😀

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