Sub Alignment: Where Does the Microphone Go?
Aligning subwoofers to mains is one of the main reasons many sound engineers invest in Smaart—it’s an excellent tool for the job. However, if you place the microphone in the wrong spot, you might be aligning subwoofers perfect for that single location but problematic for the rest of the audience area.
The Ground Plane Technique
To avoid the “floor bounce” reflection that causes deep dips in your magnitude trace, place the microphone directly on the floor. You can use a dedicated ground-plane plate or simply lay it on a piece of foam. This makes the direct sound and floor reflection arrive at the same time, resulting in a much cleaner measurement trace.
The Alignment Spot
Always perform the alignment at the acoustic crossover point—the position where the subs and mains are equal in level. This is typically about one-third of the way into the audience area. If you align at the front row, the timing may be correct there but off by the time you reach the FOH position farther back.
Follow these guidelines for better sub-main alignment and a more consistent low-end experience across the room.
Strong Warning: Avoid Left/Right Spaced Subwoofers Whenever Possible
Left/right spaced subwoofers are widely considered poor practice in professional live sound and should be avoided if at all feasible.
Separating subs too far apart so they can not couple efficiently (the typical left and right stacks) creates severe interference patterns: massive “power alleys” of excessive bass down the center and deep cancellations (nulls) off to the sides. This results in wildly uneven low-end coverage—boomy in some seats, weak or missing in others. No single delay or polarity setting can fix the geometric issues across the entire audience area.
Industry experts like Bob McCarthy, Merlijn van Veen, countless pro forums, and our now Mr. Züllich, overwhelmingly recommend sensible spacing of subwoofers for even coupling and consistent bass response. These arrangements provide more output, better summation, and far smoother coverage.
Left/right spacing may be forced by stage logistics, sightlines, or legacy setups, but it’s a bad compromise that sacrifices audio quality. If unavoidable, mitigate with advanced arrays (e.g., cardioid, arc delays) or multiple measurements—but central mono clustering (a line in front of the stage for example) is always the superior choice for the audience experience.
It also effects you crossover frequency to the mid-hi system.
Smaart is excellent on its own, but most users find they get much more out of it after some structured training. That’s where our seminars come in. At TZ Audio we run practical seminars, both online and in-venue. We offer seminar-only or full “all you need packages” including software & hardware. It’s simply the fastest way to become comfortable and confident with the measuring a sound system.
If you’re in Norway, Sweden, Denmark or Iceland – or elsewhere – we offer is online seminars and traveling to Norway is a valid option too of course. We’re here if you have any questions about the software or upcoming seminars.
Thanks for reading!