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Test for inverted phase microphone?
Old 19th September 2011
  #1
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Test for inverted phase microphone?

Is there some way of testing a microphone to see if it is wired with its phase inverted?
Old 19th September 2011
  #2
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frans's Avatar
Make a new track on you DAW. Take all your mics and put them on the table, plug them in one by one and, getting close, say "bump!bump!bump!" into the mic, then the mic's name/model, making a popping sound with the b. (Do I have to mention that ribbon mics WON'T like that and some can get damaged when you do it?). So after you are through with all your mics zoom in on the waveform of your recording. The first mountain (or valley) of the waveform should go in the same direction. All up or all down, depending. If one of the mics is going into another direction, it could be wired wrong.
Old 19th September 2011
  #3
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Matti's Avatar
Easier with a sharp click like hit your table corner with a pencil or drumsticks together. Oktavas are wired
differently than most, for example. There are/where two standards of wiring mics
back in the day.

Matti
Old 19th September 2011
  #4
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filipv's Avatar
Inverted? Inverted from... what?

When the sound wave reaches the mic membrane, the membrane starts moving backwad-forward-backward-forward. What is the correct direction of the waveform in the wave editor when the membrane moves away from the source? Up or down?
Old 19th September 2011
  #5
Set a mic up next to the MUT (mic under test). Match gain. Sum to mono. If the low end cancels out, it's reversed polarity. If you flip the phase switch and the low end comes back, that's telling you.
Old 19th September 2011
  #6
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Matti's Avatar
Quote:
Originally Posted by filipv View Post
Inverted? Inverted from... what?

When the sound wave reaches the mic membrane, the membrane starts moving backwad-forward-backward-forward. What is the correct direction of the waveform in the wave editor when the membrane moves away from the source? Up or down?
Pin 2+/3- for left output, pin
4+/5- for right output, and pin 1
is ground, positive voltage
(related to pin 2 and 4) when
diaphragm receives positive
pressure. (Diaphragm moving
inward)

From one manufacturer ( a stereo mic here )

Matti
Old 19th September 2011
  #7
Quote:
Originally Posted by filipv View Post
Inverted? Inverted from... what?

When the sound wave reaches the mic membrane, the membrane starts moving backwad-forward-backward-forward. What is the correct direction of the waveform in the wave editor when the membrane moves away from the source? Up or down?
Most mics are wired so that pressure on the diaphragm creates positive voltage. It's a convention. But it makes a certain sense, I think.
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