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Church Sound: Methods For Doing System Line Checks
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Testing DI (direct box) lines can be a bit tricky, and we often short-cut it. Because DIs rarely go bad (though I did throw a bad one away 2 weeks ago…), we normally just check the line.

I’ll unplug one of the vocal mics and plug it into the mic line coming out of the DI. It’s good to make sure you plug the cable back into the DI when you’re done.

If you want to be extra thorough, you could pick up something like a Whirlwind Q-box or a Behringer cable tester that has a built-in tone generator.

You can then plug your 1/4-inch cable into the output of the tester and generate some tone. That tests not only the cable, but the DI as well.

So that’s the easy way to do it with two people. If you’re the only one around, you can do it yourself.

Resist the temptation to open up all the channels at once, put them in the house and check the mics. You’ll find out if you have signal, but you won’t necessarily know where it’s going. If you have a really simple setup, you can get away with this, but throw in a snake, a sub-snake, some cross-patching and you can quickly find yourself chasing a fox through a cornfield.

Plus, think of all the exercise you’ll get running back and forth between FOH and the stage to check each line. Or you can do them in groups of 2 or 3, then at least you’ll be close.

Now for the super-geek way to do it. I used this method last weekend—I was mixing, and I was also tech directing—which meant I had no one around to help line check.

Since our front of house position is up in the balcony, I didn’t relish running to the back and upstairs, then back down 18 times to check all the lines. Call me lazy. So I got my geek on.

To make this work, you’ll need a few things: First, you’ll need a digital console you can control from a computer; a Yamaha M7 works well. Second, you’ll need said computer, a laptop, really as a desktop defeats the time savings, and the software to control said console.

You’ll also need a wireless connection for your console. And finally, you’ll need something along the lines of a Rat Sniffer.

To put this in play, unplug each line from it’s mic, plug in the Sniffer and use your laptop to turn on phantom power for that channel. If it’s normally on, turn it off. The sniffer picks up on phantom power and will tell you if you have a cable fault. When you turn on phantom, the lights will light up and you know you’re in business.

Plug the line back into the mic, and move on to the next one. Work your way to the end, and you’ve done a line check without making a sound (make sure you set phantom back to the correct state for each channel when you’re done).

Now sure, you could use the laptop to turn on each channel and shout into the mics, but where’s the geek cred in that?

Using this method, I had the whole stage checked in just a few minutes, all by myself, without making a sound and without breaking a sweat. As my daughter would say, “Geek Squad…”

Now get out there, and check those lines.

Mike Sessler is the Technical Director at Coast Hills Community Church in Aliso Viejo, CA. He has been involved in live production for over 20 years and is the author of the blog, Church Tech Arts . He also hosts a weekly podcast called Church Tech Weekly on the TechArtsNetwork.

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