Ground Loops

284

03:15:17

So if you follow the G+ community you'll see what I'm having an issue with 60Hz signal traveling through my speakers. This can be a possibility of a ground loop. Ground loop is when a small signal is allowed to travel on what is considered the ground of your power source or audio signal because there's a slight resistance between that ground and the absolute ground that everything is being tied back to.

So in theory with the - of the battery charger being tied to the ground of the power line it could be transmitting a 60Hz signal from the output of the step down transformer and I could be picking that signal up on the - to my amp which is amplified to my speakers, causing an audible hum.

This resistor shows you how the 60Hz pulse could be picked up very slightly, but enough to drive an amplifier crazy.

published 11 years ago

thebugger

11 years ago

From my experience there are mainly 2 reasons for noise. 1st hum from the power supply. If the ripple gets into the preamp and gets amplified you'll most surwly hear it. That can be avoided with a zener diode ar the preamp's supply. 2nd the ground loops you are referring to. I assume your amplifier is grounded from the outlet? If so you're having the same problem as me. I figured that many noises come from the outlet. Whether from a cheap phone chargers or other digital equipment they always find their way into my amps. So try disconnecting the outlet ground. Use the ground only on the transformer and not the amp circuit irself. For me separating the ground paths worked. Give it a try ;)

ETJAKEOC

11 years ago

No no my friend, it's all 12VDC, EVERYTHING is tied to the battery :)

rich11292000

11 years ago

The noise is the charger recharging the battery. If you don't want a 60hz hum, remove the 60hz battery charger from the circuit. A battery charger is not designed to be a clean power supply for music.

ETJAKEOC

11 years ago

Yes, I know, but with the amount of capacitance I have at the amp side it should block out that harmonic lol

thebugger

11 years ago

That's not what i meant. At all. a phone charger has switching noise. It may even be in another room and still affect your circuit. And also no capacitance will help you with that noise because it's not the power supply noise you must filter but the ground noise. And that is not easy. You must separate the ground of your circuit from the ground of your outlet. Doing so will decrease the ground resistance enough that no significant noise will loop back into the amplifier.

ETJAKEOC

11 years ago

Yeah but a transient filter can help greatly reduce switching noise, so maybe I have to build a special one on my charger? :p

joshuaherman

10 years ago

You do realize that in your circuit you are amplifying your power with a 10:1 transformer.

kuryente18

4 months ago

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