I've bought a Millennium SP 31 isolation transformer to split 1 phantom powered mic source into 3 outs (1 link and 2 iso). Plugging all outs into one mixer works fine as expected. But if I plug the link into one Zoom recorder and an iso out into another Zoom, the iso out has a really bad buzz like there's a flourescent light or a CRT nearby but there isn't. Lifting the ground makes no difference.
What does work though and completely eliminates all buzz and hum is to join all grounds together to the case. As supplied, only the mic input was connected to the metal case.
My question is: What's the down side of doing this? On a brief check it sounds OK. Is there some prob that could occur under certain circumstances? Or maybe full isolation is only important for power supplies but for mic level it's fine? Why did they not suply it with grounds connected? I've never used a passive splitter before - please enlighten me
PS new here. Surprised that the word 'microphone' doesn't appear anywhere in the main forum contents.
What does work though and completely eliminates all buzz and hum is to join all grounds together to the case. As supplied, only the mic input was connected to the metal case.
My question is: What's the down side of doing this? On a brief check it sounds OK. Is there some prob that could occur under certain circumstances? Or maybe full isolation is only important for power supplies but for mic level it's fine? Why did they not suply it with grounds connected? I've never used a passive splitter before - please enlighten me
PS new here. Surprised that the word 'microphone' doesn't appear anywhere in the main forum contents.