Behringer Mixer Or Mic Buzzing

Ed Fones

Well-known member
Moved equipment and dismantled and put back together. Not added anything or taken away and all plugs in same sockets etc. But this little mixer has started no to hum or buzz in the earphones. Not picked up through mic as switch off mic and still same hum/buzz.

Any ideas?
Yeah you introduced a ground loop probably - connect things until you hear it - if nothing but the mixers plug in - then you might have blown a Capacitor or possibly a Resistor.
Yeah you introduced a ground loop probably - connect things until you hear it - if nothing but the mixers plug in - then you might have blown a Capacitor or possibly a Resistor.
I pulled everything out until only the headphones in and buzz/hum still there. Does this mean its scrap?
Its when i plug the mic in to either mic sockets. But the mic has no power except from the mixer at 48v. Gain isnt even on number 5.
It has always worked with or without phantom power supplied by the mixer. The mixer is a Behringer 802. Microphone is a Monacor pdm 302
No Raymond all good there. It is strange, but there is no on/off switch and it was live when all reconnected. Whether that makes any difference?
The mic spec does not mention phantom power, and is a dynamic mic, so it won't need phantom.
Does the buzz cease when you turn all the volume knobs down?
Does the buzz come out of the main outputs, as well as the phones?
If you disable phantom power, does it still buzz?
Do you have anything else you can plug the mic into, to see if the fault moves with the mic?
Yes the buzz disappears or lessons when fiddling with gain input and headphone output either way.

Mains outputs arent used or connected to anything.

Phantom power is disabled. Noise still there.

Have changed mixer mains plugs.

Will try mic into different system and report back.

Cheers Raymond.
It is the mic Raymond. I changed mics and put mics in different interfaces/mixers. There is a bit of hum/noise from these but the most is definitely coming from the desk mic. Havent a clue why now.:confused:
You've got to be systematic here - you've confused yourself - it hums with only headphones in, but then you say the buzz changes when you adjust input gain?

So all faders down, all gains down - all channels set to route to the output in the normal way. Phones connected, phones set to say, 75%, main mix to 50%. Two track not set to mix or ctrl room. eq at middle positions.fx to off and pan central. What do you hear - with phones on full, maybe a gentle hiss? Got a hum in this state and with no inputs and no other gear connected, just the power - then it's faulty. if there is no hum, move on.
Step to, turn up a channel fader knob to 75%, and as you bring the gain up on that channel, the hiss should increase - again no noise. If it hums, it's faulty. If you then add the mic, how does that work? Then turn on the phantom - a click is fine, a hum is a fault.

You need to add and enable things systematically, in a sequence you can revert when something happens. It is possible the power supply is dodgy, but that would be quite rare.

report back with how it goes.
EDIT while I was typing you sorted it. You say there is a bit of hum/noise from other mics? Why? They should not hum or be noisy?
Well if I disconnect the desk mic from the mixer Rob the noise disappears in my head phones. If I reconnect and fiddle with gain and headphone output then the noise increases and decreases.

So I put the desk mic in my Audient and the noise is still there.

But then I put my NT1A which is in the sound booth into the Behringer mixer and it was a lot better but I could detect some low noise there as well.

The whole reason for doing this was because my control desk is right outside my soundbooth and sometimes when the pc fans kicked in, I was picking up noise on recordings even though very low. But it is another job to remove such when editing.

So I moved my control desk into another room with the pc far away and that was the reason for the massive dismantle and rebuild.

Obviously something got damaged or not aware before. Strange though.
I would open up the xlr shell and the mic, to check for broken connections.
Also, for short use, the mic switch should be in the 'up' position, and for longer talking be in the 'down' (locking) position. When not talking, it should be in
centre position. This allows for plenty of connection faults.
I agree the mic seems the culprit but if the rode is also picking up noise, even to a lower level, something else may be going on. Cable breaks or connector misfiring always seem to lead to constant and loud noise. Usually hums or buzzes. Low levels of hum often suggest the hum is elsewhere, and the mic and cable are offering it a route in? Well worth double checking any wall wart style power supplies, even if they are not directly connected to anything else. It’s possible they are introducing noise into the mains system, which feeds everything. If you have any plugged in, but not connected, try removing them to see if the rode noise drops. I have one in my office that supplies the router, and it caused no end of grief. I use an old PA power amp and the noise that power supply created appeared from my monitors. Took ages for me to find. There’s no direct connection to the amp at all through grounds as it has a plastic earth pin, but it got into the wiring. Swapping it cured it instantly.
The desk mic comes with a whopping 5 meters of cable which was rolled up because the desk is a maze of wires with to pc monitors as well. So I unrolled that and moved it away from electric connections.

The mixer 12v mains transformer I have also moved away from all other desk cabling.

I think it has made a noticeable difference. There is still hiss noise if the gain is turned up on the Audient and the Behringer mixer, but at operating levels of halfway any background noise has been reduced down to the minus 75's-80's.
A bad power outlet or extension cord can cause this. Most of the time when the outlet is the cause, its because someone stabbed the wires in the back of the outlet instead of using the screw terminal on the side of the outlet. Are you sure you used the same power cord? Because that can cause it too.