[craig62]

You'll find many of the WhoWeeds discs have similar looking spectrographs.

Here's the lineage I have for WW13:

From a cassette master transferred to wav/cdr/shn after much tweaking & adjustment.

I think a lot of "tweaking & adjustment" was performed on the sources used for many of these discs.

Here's the frequency analysis for d1t06 from WW13: