by Curt Taipale
I would like to think that every church sound tech has learned (some the hard way) that you want to turn your power amplifiers on last, and off first. Following that procedure will prevent any loud, potentially damaging pops or thumps being heard over the loudspeaker system.
If all of your sound equipment is located right there in the sound booth with you, then lighting up the gear should be a simple procedure. But what if your amplifier rack is backstage somewhere. To spare you the trek to the amp rack before and after every service, you could install some type of system to turn on the power to the rack remotely.
Of course there are plenty of churches with systems so small that they have installed a simple light switch to power up the system. Technically there should be two switches – one for the front-end equipment like the console and signal processing, and a separate switch to light up the power amps. Assuming those switches have been safely installed, that solution may be adequate.
An “AC Sequencer” is a more elegant solution that you may want to consider. Rather than the AC circuits feeding the outlets for the sound system directly, the circuits are first fed through properly rated relays. When those relays are energized, the connection is made and the power is fed to each outlet one at a time, in a specific sequence that you determine.
So how do we ensure that the FOH console is turned on first, and then the system EQ, and then each of the amps? We simply have our electrician wire the circuits in that order. When you hit the On button, the sequencer will turn on circuit #1 first, wait a moment, then connect circuit #2, wait a moment, and then circuit #3 and so on.
I keep mentioning the On and Off button. One advantage to an AC sequencing system is being able to turn the entire sound system on or off at the push of a button. But wait, there’s more. What if you have had problems with unauthorized individuals turning on the sound system and using it? You can solve that by installing the AC sequencing system with a Key Switch. At the end of the services on Sunday, turn off the system, remove the key, and the system cannot be powered up without the key being there.
The system that I often specify for my projects is the model PDS-10 made by LynTec. (www.lyntec.com). It comprises a twelve inch square electrical box that is mounted as a “sidecar” on the wall typically next to the circuit breaker panel that feeds power to the sound equipment. The circuitry inside that box controls its relays, turning them on and off sequentially. The unit can be ordered with four, eight or ten relays. Other products are available for larger circuit counts. Since we are talking about line voltage here, a qualified, licensed electrician must install the unit.
One code requirement in many cities is for the building’s fire alarm system to turn off the sound system so that the occupants can hear the emergency announcement system. Imagine that you’re in the middle of a service or a special worship night. The sound system is running pretty loud. A safety sensor indicates smoke or a fire in the building, and sets off the emergency evacuation announcement. It could be that the sound system for the worship service is loud enough to drown out or at least mask that announcement so that no one knows of the danger.
To mitigate that problem, the LynTec sequencer can be interfaced with the fire alarm system so that when the fire alarm trips, it sends a signal to the LynTec unit which then immediately kills the AC power to the audio amplifiers, instantly turning off the sound system. Although there are other ways to accomplish a similar result, that one feature alone makes including the AC sequencer an easy decision.
A handful of companies make AC sequencers. In the audio world, consider systems from LynTec, Middle Atlantic Products, Lowell, Surge-X, Furman, Juice Goose and Atlas Sound.
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