We get calls into our Help Desk from time-to-time from customers who have just bought a new pair of our speakers and a new receiver and their Automated Room Correction (ARC) app is reporting that one or more speakers are out of phase. Understandably these customers are upset that after spending a lot of money on some new audio equipment, a computer in their receiver is informing them they have a phase issue.
When we try to explain to our frustrated customer that his phasing issue is not really an issue, but the fault lies within the way the app is testing the speaker, people are sometimes left feeling we're just passing the buck. But, understanding exactly what the ARC software is reporting helps us determine what information we can dismiss and what information needs to be acted upon.
Phase (Shifting) vs. Polarity
If your ARC software (Audyssey, MCACC, YPAO, Anthem, PDK – to name a few of the hundreds that are available) reports that one or more of your speakers are out of phase, check to make sure the polarity is correct (i.e. the + is wired to the + and the – is wired to the – ).
Polarity simply refers to the way the speakers are connected. If the polarity of one speaker is reversed from the other, then your speakers are wired with opposite polarity they will be out of phase with each other (e.g. Speaker A pushes out while Speaker B pushes in, thus reducing the amount of air that is moved causing weak bass and a non-descript stereo image).
Here’s Why You Can Ignore ARC Phase Warnings
When an audio signal passes through a low-pass filter (sending low-frequencies to the LF drivers and high-frequencies to be dissipated as heat) it is delayed. This delay can happen either because of the roll-off of the LF driver or the latency inherent in the crossover: the more severe the filter (the more effectively it blocks high frequencies) the longer the delay.
When a signal is high-pass filtered (high frequencies are sent to the driver and low frequencies are dissipated as heat) the signal is not delayed. The problem we face instead of delay is an inherent ringing (or "bounce", and as the severity of the filter increases so does the amount of ringing.
If you check your speaker wiring and all is correct, then you can go ahead and ignore the out-of-phase report from your ARC. As powerful as most ARC software is, all it really does is check speaker polarity without taking into account that speakers (all speakers, not just ours) necessarily manipulate the phase of the drivers within the speaker cabinet to compensate for the phase shifting that occurs in the passive crossover network. The software is doing exactly what it is designed to do: Alert you that there is a speaker with a different polarity than the software wants it to have. It's up to the user of the software to determine if a change is necessary or not. ARC is a tool, nothing more, nothing less, and we have to know how to use the tool properly to get the most out of it.