I can't figure out why I'm getting such an annoying buzzing sound with this mic and my camera. I've tried all of the Audio encoding modes, stuck with G.711Mu for now. The only thing that brings the buzzing sound down is to turn the Noise reduction up to at least 81 but then the regular ambient sounds are mostly filtered out. Anyone have any ideas on what to try?
Microseven M7WP-MIC microphone with Dahua42212TNI - buzzing noise
- Thread starter marklyn
- Start date
tigerwillow1
Known around here
Are you powering the mic and camera with the output of a POE splitter? Do you recognize the hum as either 60 Hz or 120 Hz?
It is being powered by it's own power source independent of the camera power source. No, I don't know the difference between a 60/120 Hz hum, how can I tell and what might that tell me?
tigerwillow1
Known around here
In asking about 60/120 Hz hum I was assuming North American power. Elsewhere it might be 50/100 Hz. If you don't happen to be able to recognize the hum frequency it's not a good question for me to be asking. With the mic powered by an independent source I'd guess the probable cause as either (1) Dirty power to the mic or (2) A ground loop. If you're able, I propose that as a test you temporarily power the mic from a battery. My opinion is that odds are the hum would go away.
The power source for the Dahua camera mic is separate from the camera power supply (which is POE). The mic power supply is a two pronged plug, plugged into a small extension cord (also 2 pronged), which is plugged into a 2 prong power outlet. There are no 3 prong plugs involved. I even got a long extension cord and plugged just the mic power supply into it and plugged it into a different outlet that is definitly on a different circuit, but I still have the hum. Does this pretty much eliminate the ground loop hum possibility?
tigerwillow1
Known around here
It's definitely a power line sync'd hum. I say only that it's likely a ground loop, not 100%. Even without a ground pin on the power plug, the wall wart's output can be tied to ground. Besides experimenting with a battery to eliminate the hum, you could try a different wall wart. They have various degrees of isolation from the power line. Grounds loops are sometimes horribly difficult to fix. Sometimes the path of least resistance is to use a ground loop isolator, often used in home and car audio systems. Or do what most of us with external mics do: Use a POE splitter to power both the camera and mic. With most of them you also need to use a 2:1 splitter cable to get the power to both the mic and camera. I've got a few Microseven mics set up this way with no hum, and you should already have the 2:1 splitter cable that ships with the mic.
Agree - the hum is from the cam's power source. Either a bad PS, PS cabling, or the PS is plugged into a circuit with noise. Test this by plugging the PS into a different outlet not on the same circuit.
looney2ns
IPCT Contributor
Turn the power supply 180 degrees and plug it back in. Any change?
It's most likely the power supply you are using, you will need to try another.
Is the camera properly grounded as it should be?
It's most likely the power supply you are using, you will need to try another.
Is the camera properly grounded as it should be?
UPdate, I tried yet another power outlet that I know is not on the same line. Tried a different power adapter. Still no change.
I need to find a wiring diagram to be sure I"m connecting the right wires from my camera to the block.
Right now I've got the white wire from the camera to the positive screw on the block and the red wire from the camera to the negative.
Looks like attached.
I need to find a wiring diagram to be sure I"m connecting the right wires from my camera to the block.
Right now I've got the white wire from the camera to the positive screw on the block and the red wire from the camera to the negative.
Looks like attached.
Attachments
I've tried two power supplies, same specs and tried turning it around.
I tried red on + but it made no difference that I could tell so put them back (white +, Red -)
Power supply out is 12v 1000Mz.
Cam's audio setting is "LineIn"
sorry milliamps, basically 1 amp, right?
Yes, so PS is correct.
tigerwillow1
Known around here
Good idea to post the pictures. Read the tag on the camera pigtail. Looks to me like it says:
Red=Audio Out
White=Audio in
Black=Audio gnd
You should be using the black and white wires. Additionally, make sure black goes to the outer shell of the RCA connector, white to the center pin.
Red=Audio Out
White=Audio in
Black=Audio gnd
You should be using the black and white wires. Additionally, make sure black goes to the outer shell of the RCA connector, white to the center pin.
tigerwillow1, i looked at the labels on the wires but I guess I'm all fouled up as what subjectively might mean audio in/out.
I thought audio out (red) meant what audio was coming from the mic via the camera was one of the wires I should have used.
Can you further explain this (having a hard time wrapping my head around this).
I thought audio out (red) meant what audio was coming from the mic via the camera was one of the wires I should have used.
Can you further explain this (having a hard time wrapping my head around this).
looney2ns
IPCT Contributor
Use only the White and the Black wires. The audio (red) out is for adding a speaker outdoors so you could "talk" to a perp.
For the mic, White and Black are the wires.