I'm getting a ground loop hum when the 12v trigger wire is connected between the preamp and power amp. I have ruled out everything source wise and tried an earth ground between the two components without success. If I remove the ground connection completely from the trigger wire gets rid of the hum and the trigger still works. I know running without a ground is not great solution if something should ever go wrong in the trigger circuits of either the preamp or amp.
Putting a 480ohm resister in series with the ground should still allow the circuit to complete but break the ground loop. Question is, is this better/worse than no ground at all?
Putting a 480ohm resister in series with the ground should still allow the circuit to complete but break the ground loop. Question is, is this better/worse than no ground at all?
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Awesome! Thanks for the reply. My electronics level is DIY and therefore just enough to be dangerous. I used ohms law to calculate the 480ohm. Does that not apply to this application?
Ohm's law isn't relevant, you just need to have much more resistance than the part of the ground loop that's injecting voltage into the amp, which is typically a piece of copper wire.
Think resistive divider, with the trigger ground being the top resistor...
Think resistive divider, with the trigger ground being the top resistor...
You can use any resistor value that works reliably in your system, and still does not contribute audible hum.
Probably, 10R is about as low as you could go.
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Thanks everyone! I tried 10ohm and still had hum, went up to 100ohm and its quiet so running with it.