Adding alarm to Reaper’s JS Channel Phase Meter

I recently wrote a post about phasing problems; why they occur, what they do, how to avoid them and how to spot them visually in your DAW. Since then, I’ve found another simple way for Reaper users to detect if there are any phasing problems in their mix – by using a modified version of JS Channel Phase Meter which comes packed with reaper. I imagine this method is most useful for projects with a lot of audio, such as those mixing sound for movies (which Reaper now is useful for) and the like.

JS Channel Phase Meter is a simple plugin by Michael Gruhn that lets you monitor mono / stereo channels to check for out-of phasedness. It’s made so you can sit and watch it as you play back and see if your “in phase” becomes “out of phase”. But what if your mix only was out of phase for a short while and you missed it? In this post, user Tale on the Cockos Confederated Forums has a simple solution on how to add an alarm to JS Channel Phase Meter. I’ll explain his solution here which is about adding some simple code to the plugin.

DISCLAIMER: This could screw up JS Channel Phase Meter. You’ve been warned.

1. Load up JS Channel Phase Meter

Load up FX on a track that receives the sound you want to scan for phase problems, for example a folder track that contains your recordings. Then click FX and load JS Channel Phase Meter. It comes packaged with Reaper.

2. Modify JS Channel Phase Meter

After you’ve loaded it up, take a look at it and click edit.

channel phase meter

This will let you look at and modify the plugin’s code. This is where you make Tale’s modifications.

First, find the list of sliders (slider1, slider2, slider3, etc) and add a new line containing the following code:

slider5:0<0,1,1{Never,At Least Once}>Out Of Phase

Then we’re gonna replace a few lines. Find the following code:

phase > 0 ? slider3=1:slider3=0;

Replace it with this:

phase > 0 ? slider3=1:(slider3=0;slider5=1);

Then find the following code:


And replace it with this:


After that, you should have gotten a new drop-down menu in your plugin that’ll say if the plugin has detected phase cancellation at least once.

3. Put it to work

Once the new code is up and running, simply play your sound. You don’t have to pay attention – once JS Channel Phase Meter has noticed something is amiss, the bottom drop-down menu will say so. Below, I’ve triggered an alarm simply by reversing phase on one of the mics in my stereo-mic setup.

The drop-down at the bottom indicated there's been a phasing problem at least once
The drop-down at the bottom indicated there’s been a phasing problem at least once

So there you go. Thanks to Michael Gruhn for the plugin and user Tale from the Cockos forum for this simple solution.

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