Also - I recall looking at an old 3M M56 Isoloop that Lenny Kravitz wanted to buy. Here's one listed:
https://www.odysseyprosound.com/16-t...3m-m56-2-inch/
This is the one from Wally's studio:
https://www.historyofrecording.com/3M_M56.html
Here's a archive of how that came about
:
https://web.archive.org/web/20170326...audio-recorder
So supposedly that's how Kravitz got that sound... using "old iron" (borrowed that term from machinist lingo when they refer to old South Bend and such...).
I recall going over that machine, and when I saw the article about a decade later it brought back memories of how funky that thing was. The Isoloop motor looked like a furnace blower motor. All the old germanium xtors... wow.