Back in the day I would devour schematics like this to learn circuit design. While I do not recall seeing these particular ones. I saw some similar tricks in Buff (Alice/Valley people) schematics. Not many designers were fluent in logging circuits (while the Nat Semi app notes did have generic designs to help sell their precision transistors (LM300?) for logging application.
Back in 1989 I got a patent for a variant class A VCA(US04818951 Roberts), this stuff by Blackmer was way ahead (Class AB) even back in the '70s, but that was before dbx/THAT corp decided to share technology.