Hi guys, I scaled down to the Compact about a year ago and have found it to meet my solo needs as well as any L1 config I’ve had since '05, but lately I’m getting this hideous super high freq feedback that feels like aluminum foil on a filling. I have 5 yr old Digitech VL4 providing phantom power to a 7 yr old Beta 87 condenser mic. The output on the VL4 is at 3 o’clock, the vocal gain on the VL4 is at 3 o’clock. It’s going into the Compact Ch1 via the XLR input (not sure if any of this makes any difference, just getting it out of the way up front). The compact is set at 9 o’clock.
The feedback doesn’t happen all the time but it’s there. I listened to a recording of last night’s gig and zi can’t believe people even stayed to listen. It seems like the feedback happened whenever I’d voice the SSS sound.
I’ve futzed with gain staging til I puke. I hope it’s the VL4 or a mic malfunction, but I don’t know. Ghod, I hate fooling with this stuff. I just want a perfect sound ALL the time 
Help a brother out here? Thanks!!