Ground loop problem?

[arj]

There is an audible buzz from the surround speakers. The preprocessor is connected to the studio monitors through an unbalanced 25ft DIY IC. It took me a great deal of effort to isolate the problem and conclude that the airconditioner is causing the interference. The noise goes away when it is turned off. I always keep the volume at 100% on the speakers so reducing the volume ofcourse, reduces the noise but that I do not think is an ideal solution. As per suggestions given in various forums, I have tried to fuse the pin 3 to the XLR casing on the speaker end, tried to lift the electrical ground from the power outlet (I know its not advisable), plugged everything (PC/prepro/sub/speakers and even projector) into a single power outlet, but the noise wouldn't go away. Surprisingly the monitors on the front do not have this problem (< 10 ft cable).
.

i used to have a problem in my rig..finally isolated to the tube light !! so now i keep that light off.

Anyway to check if it is the cable, maybe you could also try wrapping an Aluminium foil around the cable section near the AC ?

 

[Thad E Ginathom]

one more observation was that there is a 1.6 V supply measured between neutral to ground connections.

In one London home, I had over 20v. That might have been part of the reason for the huge buzz when using the TT (although TTs are hum-prone anyway) and it was certainly the reason for tangible "live" feeling from metal cabinets. I earthed to a nearby pipe.

 

[gobble]

Get the earth wiring checked. Its likely a problem there.

G0bble

 

[Thad E Ginathom]

Yeah, it probably was the wiring: I did it! :lol:

But, anyway, I left there in 1980-something.

 

[Santy]

Possibly yes.
Irony is that there are two wires connected to ground pin.
One insulated and another bare wire. Still there is a stray voltage.

 

[IndianEars]

Santy said:

One insulated and another bare wire.

I dont quite understand .....

Are you referring to a specific home / installation ?

 

[Santy]

Santy said:

Are you referring to a specific home / installation ?

Yes I am referring to the room in my apartment only. I am thinking of adding a a 100 ohm resistor before the ground pin.

Haven't checked other room ground connections. The neutral to earth voltage is 0 in those rooms.

 

[IndianEars]

I am thinking of adding a a 100 ohm resistor before the ground pin.

Effectively, it will make the Ground pin useless. You may as well not connect the Ground wire .

Ofcourse, this would also be in violation of the electrical safety standards ....

 

[jls001]

Neutral-Ground ought to be ~ 0.5V AC. 1.6 V is on higher side, but not so high that it will start playing havoc.

 

[Santy]

Effectively, it will make the Ground pin useless. You may as well not connect the Ground wire .

Ofcourse, this would also be in violation of the electrical safety standards ....

Will be also adding a bridge rectifier for faulty currents to pass through without resistance. This is explained here. Not sure if it would work though.

 

[gobble]

Effectively, it will make the Ground pin useless. You may as well not connect the Ground wire .

Ofcourse, this would also be in violation of the electrical safety standards ....

Correct, it has to be the path of least resistance for the ground to work for what it is intended.

Before you add a complex circuit, find out why the voltage difference is there on the earth<>neutral line.

G0bble

 

[greenhorn]

I had random noises coming in when I plugged my laptop to my amp, and i was tired of running it on battery (it kept shutting down pretty soon)

bought a ground loop isolator of ebay, and it solved everything

These things really work!