I just got a condenser mic that uses phantom power and I connect this to both of my inputs (using xlr female to 2 xlr male y-Cable) on my scarlet 2i2 audio interface. I needed to do this to record in quicktime (which only records in stereo). This works good so far. But I was wondering if phantom power's powering it twice might it blow up my microphone or something?

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    Does the 2i2 not come with some kind of software configuration interface, where you can just pan an input centrally? – Tetsujin Nov 5 '19 at 19:39
  • @Tetsujin it does but I didn't find that option. – foreyez Nov 6 '19 at 4:20

It won't blow it up, because the +48V is the same voltage source, via some resistors of typically a few kilohms. So all you are really doing is decreasing the value of the resistors. They aren't critical and the mic should work fine.

But it's really not a good idea, because you are also shorting the inputs of the two mic amps together, and they just are not designed to work like that. At best you might get a degradation in noise performance and so on, at worst things might start to oscillate or do odd things, possibly at frequencies that you will not hear. I mean - it might seem to work, but things are a bit unpredictable and you could run into all kinds of odd problems.

The way to do this (analogue domain) is first put the mic into a preamp, and then connect the preamp out to two line inputs (L+R).

But there is a much easier way - just record a mono track and then use Audacity or similar to duplicate the recording into both channels of a stereo wav file. This is the way to do it with digital perfection.

(Of course, there is such thing as a mono wav file - are you sure you need a stereo one with identical L and R channels?)

  • if I don't do this quicktime just records to one ear. I suppose I could do it with software but it sounds like more work. how about if I used a dynamic mic instead of a condenser one, would I then be "safe"? – foreyez Nov 6 '19 at 1:25
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    @foreyez how about using instead of QuickTime a proper DAW that doesn't have such an obnoxious limitation? Most of them will just do the right thing by default (mono track to both stereo channels), if you select a mono channel. – leftaroundabout Nov 6 '19 at 15:42
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    @leftaroundabout gotta do screencast. I did find a software solution though! ffmpeg -i stereo.mov -codec:v copy -af pan="mono| c0=FL" mono.mov – foreyez Nov 6 '19 at 17:57

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