I think this is worth sharing.
In early May, I was doing sound at the Friday night service at Emanuel Synagogue. The lineup comprises keyboard, miked percussion and violin, acoustic-electric guitar and electric bass, as well as a number of vocals.
All was going well for about 15 minutes and then things went awry. Pretty much any of the signals from the various sources sounded distorted through front of house and the monitors.
Unable to find a simple explanation, we rebooted the mixer, and then changed over to the floater during a quiet section of the service but the problem remained. We finished the service with just the keyboard, the rabbi and the cantor. My hunch was that the DIs had been toasted.
I took the mixer and DIs home after the service and they tested out fine. And then I remembered hearing that sound at a concert. It is the distorted sound that some acoustic-electric guitars make as the battery that powers the pickup is dying. At the concert, the guitarist explained that he needed to change the battery, did so, and then the concert continued without a hitch.
When I returned the mixer and DIs to the Synagogue, I checked the battery in the guitar. It had a use-by date of November 2007! Ah… the perils of communal property. I installed a new battery and the problem was solved – almost. The question remained why the other instruments sounded distorted. My theory is that as the sound of the other instruments came through the FoH and monitors, it excited the body of the guitar, and this was amplified via the pickup with the faulty battery.We have yet to test this but I’m feeling pretty confident.