U67 MK67 RF interference
I have one of these mod kits fitted inside an original U67 body with original capsule. I’ve been suffering intermittent radio frequency interference, it sounds like a TV show. It’s very quiet, but say if I’m doing a vocal take in a sparsely arranged song, the level riding / compression would cause it to be a problem. Separate to this I’ve also been getting wandering frequency oscillation, like a fly buzzing around a theramin, this is quite loud and particularly present shortly after turning the mic on. Anyone have an idea where I can start to correct all this!? Generally I’ll turn the mic off, pull and reseat the valve and this may solve one or both of the problems. I got a second valve for the mic, a modern Mullard, but as it doesn’t come close to the sound of the Telefunken it’s not really seen much action and I’ve just been running the gauntlet each time I track.