Microseven M7WP-MIC microphone with Dahua42212TNI - buzzing noise

[djernie]

Hi All,

I have 32 of these mics. Regarding use on Dahua Cams.

1. The Dahua Camera Pigtail wires for the Audio in/out, Alarm I/O, are EXTREMELY small gauge wire. All of my cameras I have patiently soldered wire connectors along with heat shrink tubing for both Audio in/out.
2. Black is common ground for BOTH the In and Out sides of the Audio. This is the Minus - side of the power supply wire to connect to.
3. These mics have to be powered. They require 12vdc @ 17ma. I have always used a separate 12vdc 500ma power supply. I never share or use a splitter from the cameras power supply mainly due to the cheap garbage splitter pigtails as they can cause these exact same problems.
4. If you have a long dc power supply cord and you have it neatly wrapped or wound it will cause noise. The shorter the dc power cord the better.
5. If your home/business AC power mains, or any outlets are not properly grounded or any improperly shielded A/C Wiring will also cause noise as mentioned from others above.

These mics are very sensitive to surrounding or background noise. I have attached audio settings. Prefer not to use the noise filters as these mics will (I kid you not) pick up the sound of a nickel dropping on a train track 700 feet away. If you add an acrylic dome, Clear Acrylic Plastic Display Domes. or use a clear vinyl umbrella with a wind screen you can increase the sensitivity over a mile with a clear line of sight, no trees, etc...

could you post a pic on how you used the acrylic plastic display dome?

 

[marklyn]

Update: this morning I turned the audio back on via BI and the audio was again perfect. I made no changes since yesterday when I noticed the buzzing sound again. I went back through my camera's firmware recordings saved on the camera's sd card and saw that the buzzing started again yesterday at the 3:41pm recording. Then I checked for when the next "good" audio (no buzzing) started and it was at 10:53pm. I know I don't have anything that I turned on within those time frames (ie: TV, amp, etc.)
Years ago we lived in an apartment building and had a lot of interference on our landline phones during certain parts of the day. Very long story short, it turned out there was a radio transmitting tower close by that "switched their signal to south facing transmitters" daily and this is what was causing our landline issues. Could something like be happening here and if so why isn't my other Dahua camera experiencing the same issue (slightly different model of camera and mic). Just thinking outloud, ideas welcome.

 

[marklyn]

could you post a pic on how you used the acrylic plastic display dome?

Djernie, do you mind taking that conversation private, I'd really like to keep this thread on this topic.

 

[djernie]

Djernie, do you mind taking that conversation private, I'd really like to keep this thread on this topic.

No worries thanks and good luck.

 

[davej]

Maybe your buzzing is when the neighbor runs their microwave oven? I just added a Microseven to a cheap Dahua and... nothing. I'm still running BI-4 but I've never tried audio before. Went to the audio tab and did the obvious stuff. Still nothing.

 

[marklyn]

Maybe your buzzing is when the neighbor runs their microwave oven? I just added a Microseven to a cheap Dahua and... nothing. I'm still running BI-4 but I've never tried audio before. Went to the audio tab and did the obvious stuff. Still nothing.

They'd be running it for 6+ hours then. Every clip in time frame above has the buzzing.

 

[looney2ns]

This question caught me by surprise. Am I the only one not running a grounding wire to my cameras? If the camera has a plastic case, how could it connect to a grounding wire?

Most of the Dahua PTZ's, such as this one, includes a green ground wire. I was referring to this camera model only.

 

[marklyn]

Most of the Dahua PTZ's, such as this one, includes a green ground wire. I was referring to this camera model only.

I didn't notice a green ground wire in the pigtail, unless it's in another pigtail group.

 

[looney2ns]

They'd be running it for 6+ hours then. Every clip in time frame above has the buzzing.

How long is the cable that connects the microphone to the cam? Is it near any AC electrical lines.

 

[looney2ns]

I didn't notice a green ground wire in the pigtail, unless it's in another pigtail group.

Pig tail of this cam, with ground circled in red.

 

[davej]

Oh, duh. My problem is I plugged the mic into the camera 12V power input.

 

[Kells]

For others coming to this thread looking for a solution for the loud hum/feedback/ground loop, I had the exact same sound posted in the video earlier, and I was wired 100% correct for the beginning. I tried 5 different power supplies, different outlets etc... Finally one of my power supplies, the smallest one worked and removed all the noise! I searched the model, not sure what the supply was used for before, it was in my "Power supply" drawer lol.

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Not sure what it is about this supply that works better. Maybe because it's a "class 2" supply?

 

[marklyn]

For others coming to this thread looking for a solution for the loud hum/feedback/ground loop, I had the exact same sound posted in the video earlier, and I was wired 100% correct for the beginning. I tried 5 different power supplies, different outlets etc... Finally one of my power supplies, the smallest one worked and removed all the noise! I searched the model, not sure what the supply was used for before, it was in my "Power supply" drawer lol.

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Not sure what it is about this supply that works better. Maybe because it's a "class 2" supply?

Both of the cameras that I use this microphone on are POE. There is no external power supply for either of these cameras, still your findings may help someone else.

 

[Ratfink11]

1. Remember to verify all AC grounds. Run grounding wire from camera housing to ground.

2. Use the shortest possible wires for DC Power.

3. Use shortest possible wires for microphones and speakers.

 

[looney2ns]

Others have found that a low milliamp rated supply will help, such as a 500ma or less.
Us GOOD shielded microphone cable between the mic and the cam's input.

 

[Kells]

I ran about 10 feet of Cat5e with power AND audio to the mic, with this power supply I have crystal clear sound. I was nervous about power running alongside it, but the cat5e did it's job!

 

[marklyn]

Update: I never reported back here that the humming started up again... VERY long story short, I tried to use a ground loop filter, which didn't work. Then I just replaced the mic with another one and immediately had zero humming noise, good audio. I'm very happy now. The mic I bought was similar the the microseven one I had but it was a cammic, specto technologies microphone. B&H has one here: Speco Technologies CAMMIC High-Impedance Line Level Microphone with 1.5' Cable

 

[Hellurei]

Same thing here. There is something wrong with some of these microseven mics. I powered my mic with poe and sound was crystal clear. After couple of weeks humming/buzzing started and couldn't find a way to fix it. After testing all kinds of things connected microphone straight to laptop audio in, powered mic normally from wall and buzzing was gone. After few weeks buzzing was back exactly the same way as it occured when using as poe powered. There is really something werid going on with this mic and frankly I think I spent money on something that no one should. I ordered couple of different brands from amazon and they work great and there has not been any issues so far.

 

[looney2ns]

Same thing here. There is something wrong with some of these microseven mics. I powered my mic with poe and sound was crystal clear. After couple of weeks humming/buzzing started and couldn't find a way to fix it. After testing all kinds of things connected microphone straight to laptop audio in, powered mic normally from wall and buzzing was gone. After few weeks buzzing was back exactly the same way as it occured when using as poe powered. There is really something werid going on with this mic and frankly I think I spent money on something that no one should. I ordered couple of different brands from amazon and they work great and there has not been any issues so far.

This can be caused by not using properly shielded cable for the audio signal. I have a dimmer that when it turns on, cause's buzzing in my Microseven, even tho I used very good (Beldon) shielded cable.
Or routing the cable too close to AC lines can cause this.
The power supply can also cause buzzing if it is not properly filtered in it's outputs.
In your case, sounds like it's the POE power supply you are using.

 

[Hellurei]

This can be caused by not using properly shielded cable for the audio signal. I have a dimmer that when it turns on, cause's buzzing in my Microseven, even tho I used very good (Beldon) shielded cable.
Or routing the cable too close to AC lines can cause this.
The power supply can also cause buzzing if it is not properly filtered in it's outputs.
In your case, sounds like it's the POE power supply you are using.

Same cable same route same everything worked couple of weeks until it just did not anymore. I tested 12 different power supplys with different voltage and different amp combinations. I tried multiple different audio cables. Poe worked couple of weeks and then it started humming. Same thing when connected to laptop usb audio interface. Great couple of weeks and then.. I really can't figure anything else I could try. I checked time stamps from video clips when interference started and there was zero changes made at that time to my home network (wifi) or other wireless (z wave & zigbee) networks. Weird and annoying..