Humming / Buzzing Noise - Audio Setup - AC - Microphone - Apollo Twin X - Neumann TLM 103 - Furman

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What the noise sounds like:

I have a humming sound which is more or less audible depending on how much I increase the input gain / headphone output - it is also however - perpetually present, as it is visible digitally within software (such as an EQ) - the problem is something to do with either the microphone, or an electrical issue because I have eliminated the other possibilities via trial and error (it is not my computer because the noise is present while the computer is not connected to the interface/ I have used alternative interfaces / I have used alternative XLR Cables / It is not an issue with headphones as the noise is still present without the use of headphones). This noise only happens when phantom power on the Apollo is activated - This noise only happens when there is both ends of an XLR cable plugged in at both the microphone and interface entry points, if either is unplugged the noise stops. After speaking to many people, I was recommended to purchase a power conditioner as the issue may be dirty ac which is creating interference and noise. So I bought a power conditioner, plugged my interface into it, and powered it on, the noise still persists.

Does anybody, anybody at all have a possible solution to resolve this issue? I have been trying for so, long, countless hours sat looking through forums and videos, speaking which people over the phone, nothing I have tried has solved this bane of mine. On a side note, when I touch the XLR cable at the point where it plugs into the microphone, the volume of the sound decreased ever so slightly.

Apollo Twin X
Neumann TLM 103
Furman M-10 X E Power Conditioner
 
Well the key feature seems to be that the noise has swirly movement and is not hum. The clarity of the clicks? Is that a knob being turned sound really clean so this noise would seem to be produced by the computer bus noise getting into the mic preamp. It’s similar to the noise drives and monitors make when they do their thing. the preamp in the mic is transferring this noise into the audio line. The source is normally that it is superimposed on the screen of the cable, but it could be carried on the 48V phantom power. There are a few things you can try. Swapping the mic probably just reveals the problem, the mic may not be causing it. Does swapping it out remove the noise? There are some test things you can try. To blame the computer means doing the test again with the mic connected to your interface plugged into any other computer? A laptop maybe? If this reveals silence with no bus noise, the. You know the source, your computer. If swapping the computer transfers the problem, then to proceed further you need an alternate interface, and eventually you could be left with a real fault on the mic that Neumann will not find. It may just respond to noise on the cable. They wont have the rest of the system.

there is one thing you could try. A filter on the cable that will trap the noise on it passing. You need a mic cable and a circular magnet. An old loudspeaker magnet is great (but ugly). They are circular and all you do is wind the mic cable through it, wrapping the turns tightly around the circle and then securing it with ties and tape. The idea is that it allows AC to pass, but blocks the interference currents travelling on the outer screen. A tiny version is comm9n on power supply cables, a little plastic lump in the DC cable.

in your example, the audible knob turning suggests the mic gain is up quite high. I assume the annoying noise drops in level when you lower the gain? The noise products you are hearing are often present in computer systems but the vital thing is how loud they are compared to the wanted signal. Swap the mic, swap the cables, swap the computer and interface. Do it systematically. Perhaps even temporarily remove other connections to the computer. This noise travels down cables, so it’s feasible it could be a daft thing like an external drive dodgy power supply, or your router connection bringing the noise in. Something connected to shifting data around, or even a computer power supply working very near its current capacity. I doubt the mic is faulty, but it could be drawing too much power for your interface, voltage is dropping and noise increasing. An oscilloscope is a good tool for following the noise but tricky to interpret if you’re not used to using them.
 
Hello there, than you for your response I really appreciate it. I have found that the issue cannot be anything to do with the computer as this noise is audible even when I disconnect the interface from the computer. If I just plug the interface into my power conditioner and plug the microphone into the interface via XLR the humming is still there, I have also tried a different Apollo Twin X, as well as an M-Audio 2X2 interface, and also have tried 3 different XLR cables, but the noise still persists, any thoughts?
 
Also, yes the noise is present even when i lower the gain to the minimum value!
 
Am I understanding that the noise is only present when the microphone is is connected and phantom power is turned on? Have you never tried with a different mic? And, what mic (or mics) have you tested with?

p.s. (edit) I would be really good to have a recording with a test signal being captured and measured, e.g., with a phone's dB app, so we could have some point of reference on how loud this noise is in relation to something being recorded.
 
No the one thing I haven't tried yet is another Mic because I don't have one currently - is it likely to be the source of the noise? & okay i will do this for you and report back! Thank you again.
 
RTX7030R said:
No the one thing I haven't tried yet is another Mic because I don't have one currently - is it likely to be the source of the noise? & okay i will do this for you and report back! Thank you again.
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Try to borrow a dynamic microphone, i.e., like a Shure SM58 or equivalent - something that does not require phantom power. Then test with phantom power off and on. "On" will not harm a dynamic microphone, and should create no additional noise.
 
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