[Mandobart]

Playing my Carvin AG300 (bought new about a year ago) outdoors at a campground wedding this past weekend. I'm playing both my piezo pu equipped 12 string ovation and my piezo pu equipped 10 string mandocello plugged into the channel 1 1/4" jack (set for Hi Z) thru my tuner pedal, so I can mute during the service and when switching instruments. I have an SM 57 plugged in to channel 2 for the singer performing with me. The pastor is using an SM 58 plugged in to channel 3. The amp is powered by my 200 watt inverter. I set everything up earlier that day with the amp and passive aux cabinet out in front of the mics and instrument (no monitors). Everything sounded fine for the sound check. Service starts and everything sounds great for the prelude music (just me playing the mandocello although both mics are on but not being used). For the wedding party entrance I'm playing 12 string, singer is singing, sound is great. For the majority of the service the pastor is speaking, guitar muted, singer's mic on but not being used. Sound is great. We did a couple of songs for the whole assembly to sing together (I'm playing 12 string, singer leading the assembly). All with no problems. Right at the end of the ~1 hour service, with instrument muted and just the pastor speaking, a loud hiss/static noise sound comes thru the system. I shut the amp off. Pastor finished and I started playing the recessional music on the mandocello. I turned the amp back on (with the tuner pedal out of the chain this time to eliminate it and the second cord as possible noise sources) everything sounds fine (just instrument, no vocals but both mics are on) for about two minutes then the loud hiss/static noise returns so I shut everything back down.

I've used this same setup several times before with just an instrument in channel 1 and SM 58 in channel 2 for 3 hour gigs with no issues. I plan to do some investigating this before my next gig, but do any of you have a similar experience or insight on most likely cause? This was definitely not feedback, sounded more like RF noise. There is no cell coverage or AC power in this campground. There is a two lane paved road running close to the campground (about 100 yards straight line) with light traffic, could a CB transmission from the road cause this? Thanks!