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Front Lines: Why We Measure

A step-by-step tuning process for the time-pressed professional.

House system. PA du jour. Racks and stacks. Whatever we call them, most of the touring industry walks up to a different PA in a different room every day and tries to mix a show, with little to no say in how the system is set up besides the basic ability to control time, level, and EQ at the console outputs.

Too often, it feels like we never have enough time to tweak those parameters amidst putting out five other fires and trying to get through a sound check before catering disappears. But if we do it every day with just a Steely Dan song and a Shure SM58, these systems can’t be that wildly different, right?

Figure 1 shows system response measurements of systems at 11 of the venues I visited on a 3-week tour of 500 to 1,000 capacity venues across the United States. Some were line sources, some were point sources, some were ground stacked, some were flown. A varied look at the types of systems and rooms an average engineer doing a club tour will run into day to day.

Each trace is a coherence-weighted average of three on-axis measurements of one side of the PA with all EQ bypassed. This is representative of what I’m dealing with when I first walk into a room. The traces are level-normalized at 1 kHz to highlight spectral differences and smoothed to clearly show trends.

Figure 1

At The Extremes

Using flat response as a goal, the “best” system/room I encountered had about 4 dB variance across the spectrum (Figure 2). I turned it up and it sounded great. I rolled off some top end to match my preferences, but this system took the least work by far and was equally my favorite show of the tour, sonically speaking.

Figure 2

At the other extreme (Figure 3), I saw about a 12 dB variance, and not the pleasant 12 dB tilt of a system tuned for rock ‘n’ roll. Here we see an unpleasant buildup around 190 Hz. I used a large flat-top filter to bring down the whole low region from around 120 to 900 Hz (I would have used a low shelf if I didn’t have a Lake system processor with me), and then applied two parametric cuts around 200 and 400 Hz.

Figure 3

Another system/room (Figure 4) had a reasonably flat response with the exception of a 9 dB jump in the 10 kHz region. This room had a nice modern, name brand line source system. Low ceilings had forced it to be hung relatively flat with the bottom boxes right at face height. From my mix position 90 feet into the house, it was reasonably flat, but the front half of the crowd would have gotten their heads taken off if this wasn’t addressed.

Though I tend to avoid shading when systems are hung at a reasonable height, I would have loved some shading on the bottom boxes. Unfortunately, the configuration didn’t permit this as an option.

Figure 4

Instead, I went for an average. The front row was a bit bright, and the back/my mix position was a bit dull, but that was the better alternative than me having a perfect response at front of house and a ridiculously harsh system up front.

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