Need some help diagnosing this noise issue.
I built a second "Nano" ORS 87 in a TLM-103 style body and when I plug it in from the booth, it makes this noise.
View attachment 129963
There's a ferrite bead on the mic cable just below the XLR connector. I don't detect this noise outside of the booth when I use this mic at my desk with a Zoom F3, just inside the booth. I went back and cleaned the board with isopropyl and reflowed all the solder joints, added RF capacitors in at the XLR jack on the mic, all to no effect. When I switch inputs to a different preamp, the issue remains, so it's definitely happening inside the mic.
The first Nano ORS87 I built in the same style body is fine, no noise issue. The only differences between them are the affected one has an Ali T-13 transformer and a Bai Fei Li K87. The good one has a Neutrik 10/3 and a 3u capsule.
I have the same transformer combo in larger body ORS87 build and that one is fine with no noise issue through the same input.
Does anyone recognize what could be causing this?