Had a couple hours to spare while I had some file uploading to the server so I though I'd try a theory.
In a previous thread I talked about a way that wow/flutter can be eliminated in tape. The process is called the "Plangent Process". This is where they capture the bias freq. from a tape and adjust for wow/flutter. Pretty neat process. Well if there is a bias freq. on tape, can there be an actual signal up there as well.
So here was my plan. I take a signal generator and do a sweep all the way up to the bias freq. of about 150k in to a highly modified Studer A80RC with FMER Record AND Repro heads. The signal was captured into Pyramix at 24/192 via a DAD AX24. Afterwards, I'd do an FFT of the sweep and see what I got!
So.... here are some interesting graphs I got from the Studer. As you can see, there are ultra sonic signals ON TAPE!
I want to thank Ki for helping me with this!