I know...isn't this a great learning tool?! I recently acquired some tapes that were EQ'd for vinyl processing -- as I comprehend it: bass summed into mono and perhaps, modulated so it can be tracked by a cart AND highs emphasized because these are lost in the vinyl production process.
Now, I'm looking into getting a great parametric EQ -- Massenburg 8200, so I can listen to the EQ'd tapes on my home rig.
I used to use Massenburg's parametric EQ's and compressors in the recording studio at McGill University years ago. Nice equipment. He is now teaching sound recording there full-time, so I suspect they have his latest gear.