I got the answer to my original question today. I got this email form my "client" where I experienced the hum but with no idea why it came and went...


"BTW, Justin, the film maker, was here a few weeks ago to scope out my studio room for the shoot. While here we talked about the mic line noise. He tested it, and he heard it. He tested and discovered I had a bad, but very brand-new mic cable. We switched it out with another Mic cable, and the line noise is gone."

Still hope to find time some day to tell you all about this project I stumbled into. It is just now starting to go public so I can send a link at some time.

Dan


BIAB – 2025, Reaper (current), i7-12700F Processor, 32GB DDR4-3200MHz RAM, 1TB WD Black NVMe SSD, 2TB WDC Blue SSD, 1TB WD Blue, 2 TB SK NVMe, 6 TB External, Motu Audio Express 6x6