Hi All,
Just a post to say that my "mystery noise" is solved, and that my single-minded focus sometimes makes me incredibly stupid. I thought I had disconnected all of the outboard gear, but then I remembered the headphone system ( I run a Furman HMS-16 system). So I thought, ah this is the culprit and I rushed to prove it, disconnecting it totally and setting the machine to record, went into the vocal booth and sang a passage that was at the top of my range both in pitch and volume with no headphones and.... I heard the noise....with no headphones on.... and no speakers on in the control room, I heard it. It was coming from my throat. I had one of my customers sing the next day and I heard the noise when standing in the room with her with no headphones on. I then had someone younger come in and sing hard, no noise. My conclusion is that some singers, who have sung a little too loud for too long in their careers (like me), have vocal chords that create this distortion-like noise, or maybe the singer in the Hispanic group was getting over a cold? Maybe that's why it got worse as the sessions went on because their voices were tired? I don't know, but the D8B is not the culprit. Feel like an idiot for chasing a ghost all this time. Please forgive me for wasting your time. The D8B records EXACTLY what it hears.
Have a blessed day,
Mike