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This article explores reasons for considering frequency shading — as opposed to gain shading — to optimize the tonal uniformity of line arrays.

"I envy people that spend their carreers in studios or post‑production facilities.
Because there will never be enough air between them and their studio monitors
for air absorption to become a problem."

— Merlijn van Veen —

Foot room or Headroom?Figure 1Our industry is notorious for its ambivalence regarding consensus on definitions, and the definition of headroom is no exception. A recent Facebook poll revealed a 20/80 divide between the two most common definitions.

Headroom's ambiguity may stem from a paradigm shift in audio technology. And the solution could be straightforward. Where simply adopting a new term might end the status quo.

Beamwidth plots for dense to sparse linesFigure 1This may come as a shock — coming from the author of the Subwoofer Array Designer — but over the years I have grown an increasing dislike for horizontal subwoofer arrays.

The only thing they really have got going for them, is their left‑to‑right spatial uniformity — provided — they do not fall victim to one honest mistake.

First-order low- and high-pass filtersFigure 1Low‑pass filters introduce — negative — phase shift (Figure 1.1) which does not violate causality (cause and effect). That is, the filter's output does not occur before its input.

Conversely, high‑pass filters introduce — positive — phase shift (Figure 1.2) which paradoxically suggests the filter's output occurs before its input. In other words: time travel...

Beaming FrequencyFigure1The "Beaming Frequency" is where curved line‑source behavior strays from straight line‑source behavior. Line arrays are hybrid solutions that exhibit both straight as well as curved line‑source behavior.

The former causes Proportional‑Q — in the vertical plane — whereas the latter Constant‑Q. And there will be an inevitable frequency span where one behavior transitions into the other. During which vertical beamwidth will narrow, by as much as one‑third less than nominal. The frequency where vertical beamwidth is at its narrowest is historically known as the "Beaming Frequency".