I have a tube mic that is giving me grounding problems I think. I popped opened the power supply and the grounding wires all look correct. The weird thing is the sound doesn't occur with the top of the power supply off so it's usable I just would not to go on location with it. As soon as I put the top back on the noise revs up again. Has anyone heard of such a thing?
Power supply grounding issue?
- Thread starter kazanoom
- Start date
Help Support GroupDIY Audio Forum:
scott2000
Well-known member
Maybe posting the mic and schematics if you can will help someone better to help with your problem.
It won't be me as I wouldn't know but, as many details as possible will definitely help get you some suggestions....
Good Luck!
It won't be me as I wouldn't know but, as many details as possible will definitely help get you some suggestions....
Good Luck!
Post some pictures or video of the situation.
Are you sure the top cover is not touching/shorting something when you put it back in the case?
Are you sure the top cover is not touching/shorting something when you put it back in the case?
ruffrecords
Well-known member
kazanoom said:
It would help if you included your location in your profile.
Cheers
Ian
Try checking the integrity of the chassis piece-parts- is it causing a short as mentioned previously? Is the cover painted and not making metal-metal contact with other parts? That could cause issues. Check all hdwe connections for looseness or any resistance between parts. All parts should be connected to ac ground equally.
Mike
Mike
What kind of noise is it? 50 Hz hum? 100-150-200 Hz hum? Hiss?
Sometimes the lid affects the radiated field from the toroidal power transformer and it couples into audio stage. When you lift the lid, the field radiation pattern changes and it's not coupling into audio any more.
Sometimes the lid affects the radiated field from the toroidal power transformer and it couples into audio stage. When you lift the lid, the field radiation pattern changes and it's not coupling into audio any more.
It's not an uncommon problem. The chassis creates a close loop that in turn creates eddy currents in the presence of the transformer's magnetic field. You may want to create an insulation so as not to close the loop, using nylon screws and rubber tape.kazanoom said:
Another cause is that the lid may deflect the transformer's flux lines and redirect them towards sensitive parts of the circuit; in a mic PSU, that would reflect extremely bad design. That would happen whether the lid is screwed on or not.
And there is acoustic hum due to sheet metal vibrating, but I don't think that's the issue there.
