OBS Studio: How to Invert Phase for Dual Microphones

Using two microphones to record the same sound source can cause phase cancellation, resulting in a thin, hollow, or weak audio signal. This guide explains how to fix this issue in OBS Studio by configuring your microphones in the Advanced Audio Properties and applying a VST filter to invert the phase of one microphone, instantly restoring full, rich sound to your stream or recording.

Step 1: Configure Microphones in Advanced Audio Properties

To ensure the phase inversion works correctly, both microphone signals must be configured as mono sources so they interact properly in the center of your stereo mix.

  1. Open OBS Studio.
  2. Locate the Audio Mixer dock at the bottom of the screen.
  3. Click the three dots (or gear icon) next to either of your microphone sources and select Advanced Audio Properties.
  4. In the grid that appears, find both of your microphone inputs and check the box for Mono for both devices.
  5. Close the Advanced Audio Properties window.

Step 2: Add a VST Filter to Invert the Phase

OBS Studio does not have a native, built-in “Phase Invert” switch. To invert the phase of one microphone, you must use a free VST 2.x utility plugin (such as MUtility by MeldaProduction or ReaJS from the Reaper ReaPlugs suite).

Note: Only apply this filter to one of the two microphones. Inverting both will keep them out of phase with each other.

  1. In the Audio Mixer, click the three dots (or gear icon) next to the microphone you want to phase-invert.
  2. Select Filters.
  3. Click the + (plus) icon in the bottom-left corner of the Filters window and select VST 2.x Plug-in. Name it “Phase Invert” and click OK.
  4. In the drop-down menu, select your installed utility plugin (e.g., MUtility).
  5. Click Open Plug-in Interface.
  6. Inside the plugin’s interface, locate the phase inversion toggle. This is usually labeled as Invert, Phase, Polarity, or represented by the phase symbol (Φ). Toggle this setting on.
  7. Close the plugin interface and the Filters window.

Step 3: Verify the Phase Alignment

To ensure the phase issue is resolved, speak into both microphones simultaneously while monitoring your audio through headphones.

Toggle the VST filter on and off in OBS by clicking the eyeball icon next to the “Phase Invert” filter. You should notice a significant difference: * Out of Phase: The audio sounds thin, quiet, and lacks low-end bass frequencies. * In Phase (Correct): The audio sounds full, warm, and significantly louder.

Keep the filter enabled on the microphone that produces the fuller, more natural sound.