When I’m asked what the most difficult concept to explain in live sound is, the answer is pretty clear: Phase. It also happens to be one of the most critical things to understand, especially when setting up speaker systems.
But we definitely have to think about Phase throughout our entire audio system. This could be the phase relationship between two inputs, latency in plug-ins causing phase issues on console outputs, or setting the correct delay times on speaker systems to ensure phase coherency.
These last couple of issues are a little more advanced, and we’ll look at them in later posts and videos. But when we’re standing at the console getting a mix together, we’re most often thinking about the phase relationship between inputs, and this is most critical when we have multiple inputs for one instrument.
For example. If there are 2 mics on a guitar amp or kick drum, or a DI and mic on a bass, the relationship between those signals affects the overall sound of the instrument. If one of the signals has positive energy when the other one has negative energy, they can partially cancel each other out and affect the overall sound of the instrument when mixed together.
In this situation, “flipping the phase” of one of the input signals will change the sound, either for the better or worse - you have to experiment to see what works best in any situation. You can do this by using the “phase” button on the channel strip or DI.
I put these terms in quotes because we’re actually flipping the polarity of the signal, hopefully to improve the phase relationship of the signals. It’s just really common to hear these terms on stage. We take a closer look in our latest YouTube video:
I mention a few times in this video that phase in speaker systems is super important. If you want to get more involved with how that works, I highly recommend you check out my friend Nathan Lively’s excellent training at his website, Sound Design Live. He goes into great detail about optimizing speaker systems and getting the most out of your setup.