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Church Sound:Testing Cables Regularly Is A Big Key To Solid System Performance
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Operating the sound system from the mix position during a recent Sunday worship service, it all began when the first note from our grand piano was distorted.

Hmm…

We’d checked the piano channel and sound prior to the service, and all was fine.

My first reaction to the distortion being produced was to reduce the gain on that console channel, thinking perhaps the piano player was nailing the keys very hard.

Yet the problem remained. Next, I did a pre-fade listen (PFL) in my headphones – yes, it was definitely distortion on the piano channel, no question about it.

To capture sound from this grand piano, we use a magnetic pickup from Helpinstill Designs, which sends the original vibrations of the strings (the source of the piano’s sound) directly to the mixing console.

If you’re struggling to reproduce a full, natural piano sound these pickups are definitely an option to consider.

Anyway, my next thought was that someone had accidentally bumped the pickup so that it was hitting some of the strings. Oh well, nothing could be done until the service ended, so I just did my best to work around and minimize the problem.

But a quick look immediately after the service showed that the pickup had not been disturbed.

Finding nothing else visibly wrong, we set up a few microphones to capture the piano in case we encountered the same problem during the next service, scheduled to start in less than 30 minutes.

Sure enough as the service began, here it came again - big-time piano distortion!

We quickly switched over to the backup mics, which covered us without major incident.

However, how I was perplexed and facing a challenge. What could it be? Perhaps the pickup unit itself was failing – my most logical guess at this point.

Prior to that evening’s service, we needed to move the piano to a different location on the platform.

Looking at the microphone cable connecting the pickup to the XLR jack in the floor box, it finally dawned on me to check that cable. Sure enough, it was going bad.

Thus, a $10 mic cable was compromising the sound of our $30,000 grand piano fed to our professional caliber sound system!

It often is the simple things, isn’t it? And yet another hard-earned lesson for yours truly.

To avoid this disruptive and embarrassing problem, all I had to do was invest in better cables, and further, regularly (say, once a month) check the performance of each one with another small investment: a cable tester.

The truth is that our church already owns a very good cable tester made by Whirlwind (called, appropriately enough, the TESTER), but I’d simply gotten out of the habit of using it regularly. Big mistake.

There are many models of cable testers available, and most are very simple to use and understand. A suitable one can be had for less than $100 from your contractor or retail store.

A device like the Whirlwind TESTER should be able to be interfaced with a variety of audio connectors, such as XLR, 1/4-inch and RCA. Once connected, the tester should quickly show, via a simple read-out on the unit’s front panel, if the cable and connector are working properly. Many will also show polarity (don’t call it phase!) reversal.

A “hands-free” design is preferred to allow manipulation of the cable to locate intermittent problems. In particular, I “wiggle” the ends of the cable right next to the connector to check for intermittent problems, because this is the most likely location where they occur.

Cable testers and testing may not be the “glamor” aspect of audio, but it’s a bedrock that allows the more glamorous parts (such as mixing) to flourish. Why let one of the least expensive aspects of a system be its weakest link?

Gary Zandstra is a professional AV systems integrator with Parkway Electric and has been involved with sound at his church for more than 25 years.


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