When we think about designing sound systems, the first things that often come to mind are loudspeakers and mixing consoles. These are obviously core pieces of a design, and often the most expensive parts.
However, there are several other “supporting roles” that are critical in system design, and ignoring them can lead to out-of-control costs, frustration, and degraded sound quality. These topics will be our focus in this article.
Last year, I wrote a piece about how your worship space might be suited for a line array speaker system, or a point source system. Take a look at that piece here.
One of the most important subjects relating to sound system design has nothing to do with the sound systems itself per se, but rather the room. I’m talking here, of course, about acoustics.
Some modern loudspeaker products can help mitigate acoustic concerns by “steering” sound to only where it belongs, but even these products have their limitations.
The only true way to have a good-sounding room is to start with a room that, well, actually sounds good naturally. Sound systems generally can’t overcome bad acoustics at the outset.
The solution is usually some combination of absorption products in strategic locations, along with diffusion to break up strong reflections. It’s quite easy to overdo the absorption, though, or to use the wrong kind, so keep in mind there is both an art and a science to doing this well. It’s also possible that some of the limitations in any given room are due to how it was constructed and the materials used in the room, and no amount of acoustic treatment can really fix it. To get meaningful insight into this for your space, bring in an expert. In my experience, it’s been worth it every time.
Now that we’ve touched on room acoustics, let’s discuss another key part of the foundation of a great sound system: electrical power. Audio equipment is far more sensitive to electrical noise than most other types of electronics, and that’s partly because electrical noise occurs in the same range of frequencies we’re trying to reproduce. Therefore, electrical noise that’s not handled properly risks becoming part of the audio signal itself.
There are a couple ways that we deal with providing good electrical power to a sound system. The first is feeding the entirety of the sound system, including stage outlets for instruments, from a single, dedicated panel board (circuit breaker box). By keeping the audio equipment in its own electrical ‘world,’ we can help reduce interference caused by lights, motors, and other equipment throughout the building. It may also be necessary to feed this panel board through an isolation transformer (of the ‘double faraday shielded’ type) to help provide further noise immunity.
However, just using a dedicated panel board, even with an isolation transformer, isn’t enough. All audio circuits should be wired with isolated technical ground (orange) outlets. The principle behind these outlets (and the method used to correctly wire them) is that noise present in the building’s ground reference is kept as ‘far’ away from the equipment as possible.
With normal outlets, the ground connection is tied into conduit immediately, and any electrical noise caused by other building equipment will be ‘close’ to the audio equipment. That’s because any conduit will be part of a shared, distributed grounding path in a commercial facility. With an isolated technical ground outlet, the safety ground connection is carried via insulated wire back to the panel board. It is still ultimately connected to the same safety ground point in the building’s electrical system, but it is now handled in a more controlled manner that helps mitigate ground-related noise.
No discussion about wiring, electrical or otherwise, would be complete without praising the usefulness of conduit, tubes used to protect and route electrical wiring in a building or structure.
Your electrical contractor will, of course, use conduit for electrical circuits, but you should also install a lot of it for current and future use. Whatever amount of conduit you think you may need, at least double it. You won’t regret having spare capacity, but you will be quite frustrated if you don’t have enough.
Ideally, plan separate conduits for microphone-level circuits, loudspeaker lines, data, and video.
Keep in mind that none of these signal types can share conduit with electrical circuits (it’s dangerous, creates noise, and is against code). Use Electrical metallic tubing, or “EMT” type, for its noise immunity benefits, since it provides electromagnetic shielding. Rigid steel is even better, but more expensive and usually unnecessary. And be sure to leave pull strings in place, even in partially-filled conduit, to make future cable runs much easier to implement.
One of the spaces that ties all of these things together is the equipment room, which is also sometimes called the amp room. It’s important for the ease of service, and for the longevity of your equipment, that this room be both adequate in size to house your equipment racks with plenty of space around them, while also having sufficient HVAC capacity, to keep it cool 24/7.
I see too many facilities skimp on the critical equipment room space, either by making it too small; trying to coshare this equipment with other unrelated stuff; and/or not providing adequate cooling and circulation. If you want your system to last a long time, and for it to require minimal service, plan for a proper equipment room.
The final piece of the puzzle is the location of the front-of-house (FOH) booth. This is the spot from which an audio engineer will make decisions that affect the entire room, and it needs to be a place that has both accurate reproduction (well within the normal coverage of the loudspeaker system) and a reasonable representation of the ‘average’ listener position. In my opinion, the FOH booth should almost always be located on the main seating floor, somewhere around two-thirds of the way back, and slightly off-center.
While putting the booth on the floor admittedly takes up seats that might otherwise be filled by congregants, saving a few seats by putting FOH in a nonideal location can result in a sonic experience that is worse for everyone in the room. Placing the booth on the main floor gives the best ‘average’ experience in most rooms, and it allows the audio engineer to get to and from the platform rather easily. Placing the booth around two-thirds of the way back in the room provides a good listening position, but most importantly it keeps FOH from being too close to the back wall. Any time you’re within 10 feet of a rigid boundary, particularly when that boundary (such as the wall behind you or a balcony face) may produce strong reflections, those reflections can significantly alter your perception of sound quality. Keeping some distance helps minimize that issue.
Placing the sound booth slightly off-center might be counterintuitive, as it seems logical that we’d want a perfect stereo image. However, it is often easier to make accurate sonic decisions, particularly about mono sources such as speech microphones, when we hear predominantly one loudspeaker source. When you are positioned dead center between two loudspeakers (or arrays), any slight movement of your head will skew the frequency response of mono sources, and it can therefore be trickier to make good decisions. In many cases, being ten feet off-center is reasonable.
As you can see, there is a lot more to consider when designing a sound system than just loudspeakers and consoles. Those are incredibly important choices, of course, but there are many other critical details that are part of getting the system right as a whole.
When in doubt, seek expert advice, and don’t be afraid to challenge design decisions that might compromise these key areas.