How to Align Subwoofers with Mains

TL;DR

Subwoofer-to-main alignment is critical for smooth crossover transition. Use SonaVyx's transfer function to measure phase at the crossover frequency, then adjust sub delay until the phase traces align. This guide covers the complete alignment procedure.

How to Align Subwoofers with Main Speakers

Subwoofer alignment ensures smooth frequency response through the crossover region where the subwoofer and main loudspeakers overlap. Poor alignment causes cancellations that create audible dips in the 60-200 Hz range, robbing your system of impact and clarity.

Step 1: Measure the Transfer Function at the Crossover

Open SonaVyx in Transfer Function mode. Play pink noise through both the subwoofer and main speakers simultaneously. Capture the combined response at the primary listening position with a measurement microphone. Look at the magnitude trace around your crossover frequency (typically 80-120 Hz). A dip in this region indicates a phase or timing mismatch between the two sources.

Step 2: Check Phase at the Crossover Frequency

Examine the phase trace in SonaVyx around the crossover frequency. Ideally, both sources should be within ±30 degrees of each other at the crossover point. If you see a phase offset greater than 90 degrees, the subwoofer and mains are partially canceling. Toggle the subwoofer polarity (invert) and observe whether the dip becomes a peak. If inverting helps, it means the subwoofer needs a polarity flip plus delay adjustment.

Step 3: Adjust Subwoofer Delay

Add delay to the subwoofer in small increments (0.1-0.5 ms steps) while watching the magnitude response through the crossover region. The goal is to find the delay value that produces the smoothest summation. SonaVyx's live transfer function updates in real time, so you can see the effect of each adjustment immediately. Typical subwoofer delay values range from 0 to 10 ms depending on the physical placement and crossover filter phase shift.

Step 4: Verify Summation

Once aligned, the combined response should show a smooth transition through the crossover region without sharp dips or peaks. Store a trace of the aligned response in SonaVyx. Compare it against the individual subwoofer-only and mains-only traces to confirm that summation is constructive. Coherence should remain above 0.8 through the crossover band, indicating a consistent and repeatable measurement.