Vinyl spectral alteration was: Forbidden Plane

[Per Mattsson]

More OT:
Does anyone know of any study on how vinyl is altering the spectral
content of a recording?
Since I have recorded and produced a few vinyl records I know that back
then  everything under 50Hz was mono-coupled and had a slight compresssion
added onto it, or rather, it was ran thru a soft-limiter then mixed with
the mid + higher frequencies. 
Shouldn't the higher frequencies be "automatically" compressed or atlest
have a nonlinear freq response due to limitations of the vinyl itself? (It
could raise a  question: Does CD have a linear freq. respone?)
 
I've seen these vinyl-plugins for audiosequencers like Cubase, that adds
cracks and probably alters freq response aswell-it could be fun to have a
"add vinyl sound" module in the modular:)

---Per