This is the third part of our series focusing on subwoofers. The first and second parts are available here and here.
Woofer Array Types
In pro audio, we find several kinds of woofer arrays. In this third installment we’ll discuss flown and gradient arrays.
7. Flown Arrays
Flown subwoofer arrays are usually one box, or at most two boxes, wide.
Thus, they have very broad horizontal coverage. At the same time, the arrays are usually long, which leads to vertical coverage that is often too narrow.
In particular, there may be a lack of subbass in the first few rows of seats. Solutions are:
1. Curve the arrays in the vertical plane, as is shown for the horizontal case in Figure 10 and Figure 12.
Curving is often visually desirable, in that it tends to align the face of the woofer stack with the face of the high-mid stack. However, it only works well for very tall stacks.
2. Add a few groundstacked woofers at center stage. Make them just loud enough to cover the affected area.
Adjust the delay and level for even coverage over the front 10 to 20 rows. This is a common approach, but it’s tricky to tune it for even coverage.
3. Use beamforming. This is usually the most effective technique for flown arrays.
Figure 17 through Figure 19 are results from the LAPS line array modeler that show a flown bass line array (eight EV XLC-215 woofers) in a typical two-balcony theater) with various solutions applied.
The charts show vertical coverage patterns for one stack only, so they don’t include any of the horizontal lobing effects that will be present, but they do give an idea of the vertical challenge.
Figure 17 shows a simple flown array with no curving, tilting, or beamforming. The bass problem in the front rows is evident.