SAM BERKOW ON LINE ARRAYS

Sam Berkow knows more than a little about sound. As a partner (with Steve Sockey) in the New York City-based firm SIA Acoustics, he's consulted on the sonic performance of hundreds of studios and performance spaces. SIA also developed SIA Smaart, a standard acoustic measurement and sound system optimization software package used by audio pros worldwide.

Why use a line array rather than a conventional speaker enclosure?
Line arrays tend to work best in situations in which there is a long — rather than wide — throw or a challenging reverberant condition. The advantages of line arrays is that the directivity of the array comes from direct-radiating loudspeakers, so you eliminate the use of horns, which can have that nasal horn sound. Further, within limits, you can control the directivity via processing. The downside to line arrays can be when you need very wide coverage or a lot of control in the low frequencies where the waves get very long. In these cases, you typically require very long arrays and/or many clusters.

We like line array solutions because of the natural sound that can be achieved and for their dispersion characteristics, their controllability and the predictability of the array. For the touring industry, arrays are particularly useful because they're easy to rig. Small changes to the hanging configuration of the array can be made very easily. Obviously, in complex traditional arrays, the rigging is often more complicated and changes require much more time and effort. Lastly, we find that the tools available to predict the performance and physical characteristics of line arrays extremely useful in event/system planning.

What about using a ground-stacked line array as opposed to a more conventional delay speaker system in environments where there are low ceilings?
That can be a tough call. The problem with ground stacks is that all of your sound is at the front and with a low ceiling (12 to 14 feet), you can easily take people's heads off with the levels required to meet your throw. If you need consistent level over a long listening area in a low-ceiling environment, you might want to go with a distributed delay system. It all depends on the distribution of the audience and what the function of the sound system is.

One of the main reasons we like conventional delay speaker systems in rooms with low ceilings is for speech intelligibility. In these cases, we'll do more low-mid energy from the front and then just fill in with high-mid drivers that are distributed, either in the ceiling or from the side, using DSP to control delays and EQ. In general, I'm less inclined to look to line arrays as the solution in rooms under 12 feet with long-throw requirements. Another important consideration is that ground-stacking a line array often makes the rigging of specific/required angles much more difficult than in a flown situation.

What issues should one consider when choosing a line array system?
The first and most important consideration is the use of the system. Is it for speech, for music and for what type of music? How much low end do you need? How much power and how reverberant is the environment? A key goal with almost any sound system is to provide clarity by achieving a good direct-to-reverberant ratio. So when considering a loudspeaker system, the key questions become, “What is the horizontal and vertical dispersion you need?” Typically, line arrays range from about 70° to 120° wide (horizontal), with the vertical dispersion determined by the length of the array. Another question is, “How much power do they handle and how much directivity do you need at lower frequencies?” Examining the directivity at 125 Hz is very different than the directivity at 1 kHz, so this becomes a critical issue. This is a key difference in music and speech reproduction. Finally, line arrays are tools, and like any tools, they can be used well or poorly!