I live in europe, so my AC is 220V x 50 Hz. I am using the following rig to record sound:

  1. Studio Projects B1, the old model, cardioid microphone.
  2. M-Audio Firewire Solo to convert from analogue to digital
  3. Everything goes to my Mac.

As I speak, I hear an annoying noise that is exactly 2KHz and other noises at 1210 Hz and 306 Hz.

The most annoying is that the noise is intermittent in terms of amplitude. See this to hear.

I have added this parametric equalizer to see if I could filter the noise:

enter image description here

See that the parametric filter is configured to be centered at the frequencies I say and to minimize effects this filter could produce on my voice I have narrowed the filter actuation to just 4 Hz around the center of each frequency, except the first one that I made it really narrow. It seems to cut 98% of the noise.

Around the mic I have a few equipments like iPad, iPhone, iMac and the M-Audio. I have to have these equipments there. The mic is on a pedestal with shock absorber. I have turned every equipment off, with the exception of the Mac/M-Audio that I need on to record and test the sound without any change.

Anyway I don't like the idea of having to filter my audios. I want to solve the problem.

What can that be? Can it be the mic? Can it be lack of ground or something? I live on a modern building that have ground and apparently everything is grounded properly. The light bulb I have on the ceiling is a LED one. I have indeed turned that off without changes on the noise.

By the way, I am a newbie on the sound design business. I am trying to find my way. One of the things I am trying to find is a raw audio of a voice over so I can compare mine with that audio in terms of quality... what to expecto. I need just the audio of someone talking on a cardioid microphone without any processing where I can hear the background noise, if any and the voice. Do you guys know where I can find a raw audio like that? thanks.

1 Answer 1


The usual source is a DC/DC converter. This can be your laptop power supply (try running on battery to see whether anything changes), an LED bulb power supply (those are becoming more frequent these days, try turning off lights in sequence to look for a change), the laptop screen lighting (can you turn that off? For example, set your power settings so that the laptop will keep running when closed and then shut the lid?).

Or the phantom power supply of the audio interface (try recording with phantom power turned off: if the resulting silence is missing the whine, it's either the phantom power, or the microphone is picking up something electrically or acoustically when active). Or the power supply of the audio interface.

Try moving the mic around and listening. Any change? If so, try homing in on the source.

  • I think it may be the phantom power because when I turn it off, this happens: 1) the mic continues to work for about 2 seconds, because it is probably using power from some capacitor inside itself and 2) the noise vanishes immediately. That's the culprit.
    – Duck
    Commented Jan 19, 2018 at 17:09

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