How To Measure Phase Cohesion Through A Crossover Using Room EQ Wizard RTA, A Microphone, & All Pass Filters

ResoNix Sound Solutions Measuring Phase With Room EQ Wizard REW RTA Helix DSP

How To Measure & Verify Phase Cohesion Through A Crossover Using An RTA

       Hey everyone, I’m starting a blog to share various tech tips and useful information. For my first post, I decided to make an old video of mine available again. In this video, I demonstrate how to measure phase quickly and easily verify phase for maximum cohesion through a crossover. This is done using nothing but an RTA, All Pass Filters, and the Phase Slider on my Helix DSP. Additionally, I measure the results with Room EQ Wizard and a USB Measurement Microphone. Although I used a Helix DSP for this demonstration, it’s an older video, so some things may look a bit different. Furthermore, the video includes my old company’s intro.

       Keep in mind: this method is only for even-order Linkwitz-Riley crossovers. A perfect LR crossover will be rolled off 6dB at the crossover point. The two will sum perfectly flat to 0dB. So, a perfect LR crossover will sum + 6dB. 90 degrees out of phase LR crossovers will sum 3dB. 135 & 225 degrees will sum with no change. 180 degrees out of phase will result in a null. With this simple process, you can measure and improve phase in your sound system.

Seen below is a more traditional way to measure phase directly, which can be much more complex and unnecessary to many.

Two traditional phase measurements are pictured below, overlaid on top of each other. If you’re trying to tune your car audio system using your DSP and a simple measurement setup, this could be too complex and might cause you to get lost in the sauce.

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