How to Invert Microphone Phase in OBS Studio

Inverting the phase (or polarity) of a microphone input in OBS Studio is essential for resolving phase cancellation issues, which occur when using multiple microphones to capture the same sound source. While OBS Studio’s native Advanced Audio Properties matrix is used to route channels to specific tracks and sum stereo inputs to mono, it does not include a built-in phase inversion switch. To invert the phase of a single microphone channel, you must pair the Advanced Audio Properties with an audio filter, such as a VST 2.x plugin. This guide will walk you through the exact steps to achieve this.

Step 1: Add a Phase-Inverting Filter to Your Microphone

Because OBS Studio does not have a native “invert phase” button, you must use a free utility VST plugin (such as the Reaper ReaPlugs suite, specifically ReaJS, or mda Image) to flip the polarity of the channel.

  1. Open OBS Studio.
  2. Locate your microphone in the Audio Mixer dock.
  3. Click the three dots (options icon) next to your microphone and select Filters.
  4. Click the + (plus) icon in the bottom-left corner of the Filters window and select VST 2.x Plug-in.
  5. Name the filter “Phase Invert” and click OK.
  6. From the drop-down menu, select your VST plugin (e.g., reajs or a similar phase-adjust utility).
  7. Click Open Plug-in Interface.
  8. Within the plugin interface, select the phase adjustment utility and set the phase offset of the target channel (Left or Right) to 180 degrees (or check the Invert Phase / Polarity box).

Step 2: Configure the Advanced Audio Properties Matrix

Once the phase has been inverted via the filter, you must configure the OBS Advanced Audio Properties matrix to route and sum the audio correctly.

  1. In the main OBS Studio window, click the three dots next to your microphone in the Audio Mixer and select Advanced Audio Properties.
  2. Locate your microphone in the list.
  3. Mono Checkbox: If you have inverted one channel of a stereo microphone to correct a phase issue, check the Mono box. This sums the left and right channels together. Because one channel is now phase-inverted, they will combine correctly without canceling each other out.
  4. Tracks Matrix: On the right side of the window, you will see the track matrix (numbered 1 through 6). Check the boxes for the tracks you want this phase-corrected microphone audio to be recorded or streamed to.

By combining the VST polarity filter with the Advanced Audio Properties routing matrix, you can successfully eliminate phase cancellation and ensure clean, professional audio in your OBS recordings and streams.