a little bit of hum............... - diyAudio
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Old 1st June 2006, 06:27 PM   #1
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Default a little bit of hum...............

Hi guys, Ive got a hum problem, just need some feedback, i am currently monoblocking, Monobridging two Behringer A500 *pro Amps, and on the left channel i seem to be getting some hum. I have it in a system with a rotel pre amp, Cd player, turntable, Cassette deck

Before i say any more, sometimes i run my finger along the front of my Cd player and amp which is metal , and there is a small voltage ,static running across them. I have a small studio, and the hum is present in there, also downstairs it happens to the hifi in the front room. a small charge at times. My television upstairs has the same background interference. I have had that for 4 years, and beforehand a Audiolab 8000SX times 2, and that never gave off hummed so much.

anyway any info ideas, could be poor grounding in the power amp, the interconnects, i have unplugged everything , interconnects and all

So maybe a ring main problem? Its a bit of a lottery really.

thanks for any info
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Old 1st June 2006, 08:20 PM   #2
Netlist is offline Netlist  Belgium
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Itís difficult to confirm if the hum and the voltage present on the metal parts of the system are related with each other.
I however would advice to let an electrician have a serious look at the ground in the house and studio. Being in the consumer business, I frequently encounter houses with bad or no grounds and itís not the first time I got shocked by the cable antenna or the video and TV equipment.
It might be a solution for the hum as well.

/Hugo
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Old 2nd June 2006, 01:07 AM   #3
jaycee is offline jaycee  United Kingdom
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You need to check the earth bonding in your house. If you are getting potential build up on metal earthed items then this means your house has a poor earth.

I'd suggest getting a qualified electrician to do an EFLI test.
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Old 2nd June 2006, 01:09 AM   #4
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thankyou guys, I think i should get an electrician to check it out, its been going ona few years now, with currents running through cables it shouldnt.
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Old 2nd June 2006, 02:14 AM   #5
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Sounds like a bad neutral coming from the pole (power company pole). Maybe a bad line transformer. They should be able to clear it up.
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Old 2nd June 2006, 03:20 AM   #6
lndm is offline lndm  Australia
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Default Re: a little bit of hum...............

Quote:
Originally posted by emperor Ive got a hum problem, just need some feedback,
Haha

If you take a walk around your house and locate the ground stake, there's a chance you may notice something obvious, like corrosion (not a substitute for a professional opinion.
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Old 2nd June 2006, 04:50 PM   #7
AndrewT is online now AndrewT  Scotland
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Hi,
being British based you are unlikely to have an earth stake and similarly no pole transformer.

Depending on which earthing system your power company installed will determine whether you have a true earth or an earth shared with the neutral incomer.

Whichever, I would go for a professional check over just for peace of mind. There is a downside, if they find a problem they will condemn it and may switch you off until it's fixed. You are then over a barrel, and price no longer seems relevant.

ps, you can buy a cheap plug top with a tester built in that checks for the presence of Live, Neutral and Earth and that they are on the correct poles. But it does not check the quality of your system connections.
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Old 2nd June 2006, 05:34 PM   #8
poobah is offline poobah  United States
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These guys are "spot on" if that's the correct term. I have sometimes foolishly ignored tingles on equipment only to find out sometime later that I was touching a solid 120 Volts AC... damp socks or barefoot is a good (BAD) way of finding these things.

Take along wire and tie it to a water pipe. Go around your house with a meter... you might be shocked (literally) at what you find.

Oh, BE CARFULL with that long wire, don't ground yourself!



EDIT: speeling... again!
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Old 2nd June 2006, 05:49 PM   #9
Netlist is offline Netlist  Belgium
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I'm glad to see the words of warning given by people in this thread. As stated many times and very nice phrased by SY some time ago: "Dead is very permanent."

/Hugo
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Old 2nd June 2006, 05:53 PM   #10
PMA is offline PMA  Europe
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Unfortunately we often face "hum" and "noise" problems . Sad to see sometimes ....
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