Speaker Placement
As you watch any given marching contest, you’re sure to see a wide variety of speaker brands, placements, angles, and more. When designing your sound system, it’s easy to get stuck doing something that someone else does, without really knowing the fundamentals of why they did it. Here are some considerations that should be at the forefront of your decisions when placing speakers on the marching field.
Speaker Dispersion
Every speaker has a vertical and horizontal coverage angle. This is heavily reliant on the model of speakers that you have. For example - Presonus CDL12P array speakers have a vertical coverage of 15 degrees and horizontal coverage of 120 degrees, while Yamaha DZR15 speakers have a vertical coverage of 50 degrees and horizontal coverage of 90 degrees. You can see that the directionality of these speakers varies a LOT. If you were to angle the center of CDL12P’s up by 45 degrees, you would be covering from 37.5 - 52.5 degrees above level. If you were to angle a DZR15 up by 45 degrees, you would be covering from 0 - 90 degrees, from level with the ground - to straight into the air!
In addition, CDL12Ps placed symmetrically on the 35 yard lines would start to overlap coverage zones much closer than Yamaha DZR15s would, because you’re talking about a 120 degree width versus a 90 degree width.
Now make no mistake, this doesn’t mean that if you stepped one inch outside of the coverage angle, that you would no longer hear the speaker. Sound obviously doesn’t work this way. However, the most clear, accurate, and powerful sound a speaker can produce will always be within its given coverage range.
Because of this, we want to make sure that we are angling our speakers properly and placing them apart in a way that gives us the best coverage in the areas we want it most. Speakers too far apart will have a dead zone in the middle, speakers angled too low won’t reach the press box, speakers angled too high waste some of your dispersion sending sound to the moon!
Feedback Concerns
If you’re playing at a venue with a 12 foot wall, and you put your speakers 10 feet in front of the sideline, you’re going to have major issues. Speaker placement can be venue dependent in extreme scenarios like this, and the reflections off of things like walls can cause major feedback issues. Knowing where you perform and gearing your audio setup for the most extreme of venues can allow you to bypass these issues if you think of them in advance.
In addition to this, placing speakers in close vicinity to open live mics can cause feedback issues easily, even with proper EQ and gain staging. Feedback occurs when your open mic’s pick up the audio from your speakers, which creates a loop that continuously gets louder as the speakers keep reproducing their own sound through the live microphone. The easiest solution for feedback, is proper speaker and microphone placement. The more distance you create, the harder it is for feedback to occur.
Matching What You Hear to What You See
As you watch contests through the season, you may see things like front ensemble on the hash instead of the sideline, or maybe offset to one side of the field. If this is something you’re interested in doing, speaker placement is a fairly large concern. My rule of thumb, is speakers follow the front ensemble. This is assuming that 75%+ of what comes out of your speakers is coming from the front ensemble, but avoids issues like delay, and helps the audience localize where the sound is coming from. Seeing your front ensemble far back, but hearing them come from speakers on the sideline, can be distracting and confusing for the audience and judges. A large issue with back field speakers come in the form of feedback through any front field mics, or solo mics. These can be navigated, but take some skill to do so.
If you have an offset pit, my advice would be to offset your speakers, but experiment with offsetting them only half as far as your pit is (i.e. if your pit is offset 10 yards, only move your speakers 5). This can help ensure you still have good coverage in the center of the field, and aren’t wasting some of your dispersion on the outside edge of your system.
In Summary
My guide to speaker placement, with these things in mind, is to TEST IT YOURSELF! Place your speakers between the 35s and 40s, get up in the press box, and listen. Walk the top row of bleachers, if you hear sound dip in the middle, move the speakers in. If you hear spikes and dips across the entire top row, you might have too large of an overlap which can create power alleys. Move your speakers out and see if it helps. In audio, especially as a band director, your ears are the best tool you have to get things to sound the way you want them to!
