Setting the Low Pass Filter LPF, Polarity

Setting the Low Pass Filter (LPF)

The Auro subwoofer LPF (low pass filter) control gives you the ability to tune the subwoofer to match your sound and room. The LPF control adjusts the internal crossover of the subwoofer from 80Hz-200Hz. Use the below points as guidelines when setting up your sound system, but always use and trust your ears when finding a setting that sounds good and fits your application.

The goal is to seamlessly integrate the subwoofer with the rest of your speakers to extend the frequency range of your system, rather than produce an unnatural, boomy mix. You do not want the subwoofer and the main speaker to reproduce the same frequencies, as this will create duplication of low frequencies, and create an imbalanced mix.

A good place to start is to use the frequency response of your speaker cabinets. You can usually find this information in the documentation included with your speakers. Set the Auro subwoofer LPF to the lowest frequency that your satellite speaker produces.

If your satellite speakers are large (12" or 15") set the low pass filter to 80Hz. If your speakers are small (8” or 10”) set the low pass filter in the 100Hz range. If you have an oscillator (there are many free oscillator smartphone and tablet apps available), slowly sweep from 400Hz down to 40Hz, and listen to how the subwoofer and speakers blend together. You may need to raise or lower the LPF control to create the smoothest frequency response. If you do not have an oscillator, use music tracks that have a steady bass line and kick drum. Slowly adjust the LPF until you find the optimum setting.

Polarity

A speaker reproduces sound by converting electrical signal into physical vibration. which pushes air to create sound waves. When setting up your speaker system, the goal is to have all speakers moving in phase, with the in and out movement of the speakers synchronized. This produces an even sound across all audible frequencies. If the subwoofer is out of phase with the full range front of house speakers, you may notice decreased bass response, or even bass frequency cancellation where satellite and subwoofer frequency responses overlap. Many times this phenomenon is very subtle, but it can produce the effect of “holes” bass frequencies.

0°	90°	180°	270°	360°
	Phase SW = NORMAL
Amplitude				Time

	Phase SW = INVERT

in the music, and diminished

Ideally, your Auro subwoofer should be positioned on the same plane as your satellite speakers. In reality, we know this is difficult, as there are restrictions when setting up a PA system due to space limitations, speaker stand configuration, or even speaker cabinet shape. To compensate for these obstacles, the Auro subwoofer features a Phase switch, which allows you to reverse the polarity of the subwoofer relative to the source signal. This enables you to put the subwoofer in phase with the rest of your PA system, or 180° out of phase.

To determine if the audio produced by your subwoofer is in phase with the rest of your PA system, play an audio track containing a lot of bass frequencies through your speaker system. Stand at a good listening distance, where you can clearly hear the audio from the subwoofer(s) and mains speaker(s), and listen until you believe you have a good gauge of the level of bass frequencies. Press the Phase switch on the Auro subwoofer to reverse the phase by 180°, and move back to your original listening position. Compare the overall level of the bass frequencies between the two settings. The correct setting will result in more bass frequencies. If the situation allows, you can fine-tune the phase of your subwoofer to your satellite speakers by moving the relative position of the subwoofer closer or further away from the listening position.