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C1000s hum/buzz on phantom power

My c1000s if connected with phantom power to my Apogee Duet makes a low hum/buzz. I've tried unplug everything and run on my laptop with battery and it happened anyway, so it isn't a ground loop problem... it's gotta be the mic right? Switch off the phantom and use the mic with a battery is perfect.

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  • Fabio
    Fabio Apr 25, 2014

    Hi Stefan, thanks so much for taking the time and help me out. As you say I think the energy is enough, especially considered that it exceed the energy the battery can supply, and the microphone is fine on a battery, no noise. So maybe the cable is good to? Is new, and is xlr both ends... maybe I should try a different cable before blaming the microphone though... I have this one from amazon: what do you think of it?

  • Stefan Mayrhofer
    Stefan Mayrhofer Apr 25, 2014

    Hi fabio. there is not much power to be delivered over the cable. It is by specification less than 10mAmps at 48V.

  • Stefan Mayrhofer
    Stefan Mayrhofer Apr 25, 2014

    Do you have a voltmeter? Check Pin 1-2 and Pin 3-2 for 30...48V each at the female XLR plug while your sound card is on and phantom activated. As you say the cable is new there should not be any broken wire inside. In this case the mic is to blame. I have the service documents here. First thing: Undo screw at the xor connector and gently pull out the connector. are the 2 wires ok? I would try another cable anyway and if possible another preamp. Just to ensure. The obvious things are checked and it sounds like something's wrong with the mic. Does the loudness change when you insert a battery?

  • Stefan Mayrhofer
    Stefan Mayrhofer Apr 25, 2014

    Further diagnostics is hard as I would need the microphone here to check the circuit. If you are experienced in electronics and say you want to try more I can tell you what to check on the mic's circuit board. best wishes & sorry for 3 posts but hitting "enter" will send the post instead of creating new line. cheers

  • Fabio
    Fabio Apr 25, 2014

    I've listened to some earlier recordings I made with the mic going through an analog Mackie mixer, and I actually recognised the same hum. I guess that at the time I just assumed it was something i had to live with, blaming the rest of the system, that was a bit hacky. I don't have a voltmeter, but I guess I could buy another cable from amazon, and if it hums again, I'll send the cable back. Then if it's the microphone I don't know, I guess I could open it but I'm afraid I could do more damage :-)

  • Stefan Mayrhofer
    Stefan Mayrhofer Apr 28, 2014

    Normally it does not hum. Maybe the best is to ask a local electronics to check the microphone. Sorry that I can't do more from here but the distance makes it way more difficult than it would be on my desk ^^

  • Fabio
    Fabio Apr 28, 2014

    Thanks Stefan, I'll try the cable first, I'll get a fender one, and then I'll move on from there. Thanks mate!



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  • 40 Answers

Possibly the microphone needs more power than your sound card can supply although I cannot imagine as the duet is a good piece of equipment.
Is the duet USB bus powered?
Have you tried another cable? Possibly one wire is defective which means that phantom power will superpose the audio signal. In this case you might hear a hum. By the way this results in 6dB of signal loss. This is why XLR plugs have 3 wires. If connected with a 1/4" jack it has to be a stereo plug (tip, ring, sleeve)

Posted on Apr 24, 2014

  • Fabio
    Fabio Apr 25, 2014

    Hey Stefan, thanks so much for taking the time and help me out. As you say the power from the Duet should be enough, it exceeds the battery power with which the microphone is fine. So maybe the cable is to blame? I bought this on amazon: what do you think of it? is xlr both ends, it's new... maybe is not good enough to bring power and sound? When I put the battery in the microphone and switch off the phantom, the sound is clean... thanks



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Posted on Jan 02, 2017


SOURCE: a buzzing sound

The cables always a usual suspect, but if you are using a tube mic, wich have their own power supply, you don't use phantom power and it can damage the mics power supply, so take phantom power off that mic and if that doesn't cure the buzz then I would change the cable next.

Posted on Aug 06, 2008

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