This is the true story of five men and their battle to exorcise RF demons from the Nautilus Theatre at Sea World, Cleveland.
There I was, at the Nautilus soundboard frantically trying to fix the wireless microphone, again. Three years as a field service technician and I had more than a few aces in my pocket and tricks up my sleeve. But try as I might, neither me nor my coworkers had been able to solve the problems at Nautilus. In fact, we couldn't even recreate them to even begin to form a diagnosis.
It went something like this: Every show we would get a call from the soundboard operator saying that about once every minute or so all of the mics in the whole stadium would cut out for a second.
We would come down after the show and walk the stage with the mics trying to repeat the problem. Nothing. No matter what we did we couldn't manage to make the signal drop out.
Just to be sure we would systematically pace every foot of the stage looking for RF holes. We would change batteries, change frequencies, change headsets, change transmitters, receivers, antennaes and everything else we could think of to try and solve the problem. We even tried making offerings to those interred below as we were certain the stage was built on an old Indian burial ground.
Our efforts were to no avail. And our bosses were beginning to breath down our necks. So, having tried to appease lesser gods, we decided to supplicate to almighty Capitalism.
We threw money at the problem.
$12,000.00 in fact. All spent on the incredibly cool, incredibly sleek, inredibly sexy (in the geek sense of the word) Beyer-Dynamics Ultra Wireless Audio System.
These German import babies were so cool they automatically gave battery strength indications on both the transmitters and receivers. They also hooked up to software that would triangulate the performer's position on stage and map it against signal strength. These things were so badass even the co-ax line to the antennaes had to be a special order, seeing as it was three times the diameter of your normal antennae or TV co-ax run. These things rocked.
Not that you could tell in performance. They cut out just like everything else we had ever tried.
About to give up all hope, we decided to call in a favor with another excellent company, Audio-Technica. The kind folks at AT listened to our horror story (especially the part where we spent 12 grand on a competitor's product) and promptly dispatched two engineers.
They arrived later in the week armed with oscilloscopes, Fluke meters, and a whole assortment of blinking, beeping and glowing whosijawhatsits and thingamagigs.
They emerged from the stadium many hours later slightly shaken, but in no way stirred. The problem, we were told, was one of the most unique they had ever encountered.
It went something like this. The stadium was constructed of very long aluminum benches mounted on wooden platforms. Due to nightly washings this wood remained damp all day long. The entire structure was supported by a rusty steel framework underneath. Essentially you had two conductive layers seperated by a semi-conductive layer. In other words, a very large capacitor.
This capacitor would slowly become charged by the smaller charges created by a stadium full of people. When this capacitor finally discharged, the ensuing EMI would cause a drop-out in our microphones.
Solution: a couple of cheap grounding rods.