The Auto EQ works in a way that is subtly different from conventional EQ methods. In those, a calibrated microphone is required, and the response measured at the listening location is adjusted to match some “ideal” response determined by the software engineer. This is not the response that was designed by the speaker engineer themselves! Ideally, when the subwoofer engineer designs the subwoofer they have an idea of what performance they want the speaker to achieve. The limitation is that the room will modify this, hence the need for EQ. But the ideal is that the EQ gives at the listening location the response desired by the speaker engineer. This is the approach utilized in ELACs’ process. It allows for a clever change in the requirement of the microphone. We no longer require a calibrated microphone. In fact we utilize the microphone built into the smartphone itself!

The process is to hold the phone very close to the subwoofer, the so-called “nearfield”. At this location, the measured response is devoid of almost any influence from the room, and is measuring in fact the designed response of the subwoofer. Once this response is captured, the smartphone is relocated to the listening location and a second measurement made. Next a set of filters is adjusted automatically to make the response measured at the listening location match that made in the nearfield of the subwoofer. The actual performance of the microphone is now of no importance: it is the same for both measurements and we are simply adjusting to minimize the difference! The sound heard at the listening location is now the one that the designer wanted you to have. It’s a very cool technique.