Room geometry is one of the biggest challenges faced by sound engineers and system designers. A single level space with a main floor can be challenging enough, especially if the room is not symmetrical about the centerline. Add in a balcony, or even two balconies, and a number of additional challenges will need to be addressed. Providing adequate reinforcement for listeners seated in and underneath a balcony can be a costly endeavor that should be carefully considered.
Acoustic Effects
A balcony not only changes the geometry of the audience, but it also has acoustical properties that affect how a sound system performs. Several years ago, I did console training at a church where parts of the balcony facade were glass. The glass portions were located at the ends of the balcony stairs, and were intended to prevent someone walking down the balcony steps from toppling over the balcony and onto the main floor. Unfortunately, those pieces of glass reflected nasty high frequency sibilance from the P.A. system right back to the downstage, creating a nightmare for vocalists. When designing a sound system for a room with a balcony, care should be taken to avoid throwing energy (especially high frequencies) directly into the balcony facade. If preventing the main P.A. from striking the balcony is impossible, then the balcony face should be treated with absorption and diffusion to minimize hard reflections coming back towards the stage.
Mains and Fills
When considering speaker placement and selection, the first question is, can you cover the entire audience with just the mains, or are under-balcony fills required? Much of this decision will depend on the arrangement and hang location of the mains. For example, if the mains are flown high in the room, the balcony will act as a barrier or obstruction between the main P.A. and listeners seated under the balcony. To verify this, stand in the back row under the balcony. Can you see the mains? Walk forward towards the stage. Does the balcony obstruct line of sight to the main P.A. for most of the listeners seated under the balcony? If so, you need under-balcony fills. However, if the mains have line of sight to the majority of the under-balcony seating, you may not need those fills. If you’re working on a design using prediction software, it is just as easy to tell if the balcony is going to obstruct sound from the mains to the under-balcony listeners. Now what about listeners seated in the balcony itself? There are rooms in which you may need over-balcony fills. In a space with a very deep balcony, where the balcony depth is much greater than the under balcony depth, delays may be required to maintain adequate SPL and intelligibility for the farthest listeners.
Drive Techniques
In a church environment, ask yourself how much control the console operators should have over the P.A. Even if you have seasoned engineers at the helm during Sunday worship, you’ll likely have other, less qualified people operating the system during the week. I’ve often struggled with how much control to leave on the console, and fill systems — like under-balcony fills — are a great example of this conundrum. The first question to answer is, what you want sent to the fills. In most cases, it’s going to be a mono sum of your left and right stereo bus. Unlike front fills, where you might want to send only select channels, such as vocals, under-balcony delays are far enough from the stage that you’re going to want the entire mix. Why mono? The listeners seated under the balcony will be relatively close to the fill speakers. Providing stereo zones only benefits a small number of listeners and will degrade the listening experience for the majority.
All of that being said, you have two options for feeding delays. First, you could feed them straight off of the console using a matrix. This leaves level and mute control over the delays on the desk. Alternatively, you could sum your left and right mix in the loudspeaker processor and feed it to the delays that way, effectively removing control of the delays from your day-to-day operators. I personally prefer this approach. Once the system is tuned and time-aligned, why risk having someone inadvertently mute or change the level of the delays?
Practical Considerations
When determining whether or not to use under-balcony delays, we can’t simply consider it from a sound system designer’s perspective. Sure, if the balcony is such that it calls for under-balcony delays, we should include them in the design. However, such delay systems are costly, possibly running into tens of thousands of dollars for a single under-balcony system. There are practical considerations as well, such as how the speakers are mounted, how they are processed and how they are powered.
Interesting Opportunities
Depending the type of space you’re dealing with and the typical performance style in the room, there are some interesting products available to address rooms with balconies. Several manufacturers offer column array loudspeakers with steering capabilities. For example, Meyer Sound’s CAL allows for multiple steering zones that can be used to avoid throwing energy onto a reflective balcony face. While these sorts of systems might not be suitable for high-energy rock music, in a room that is geared towards speech and light instrumental or vocal ensemble work, they might be the key to success. There are many options on the market today to make a room with a balcony work, and be consistent for every listener in the space.
Vince Lepore is the technical director at St. Luke’s United Methodist Church in Orlando and teaches live production at Full Sail University
