Just a guess, but if it sounds '80s remember that these tracks are mostly from 1978. Or it might be these drum tracks were ripped by somebody during the "Coda" mixing sessions. I dunno, my friend who hipped me to these drum tracks a while ago, he thinks they might be some kind of 2-track safety backup or something, yunno, make a backup of the keeper drum takes at the end of the day, before messing with the overdubs, or run a 2-track machine at the same time while tracking, or something.Anyone wanna venture a guess as to what we're actually hearing in these files, i.e., is this the drum faders with effects from the board, or, someone else's after-effects job? The 'verb sounds suspiciously 80's to me.
Also, I don't know if this is totally 100% accurate or not, but I was goofing around on the internet and I found this goofy fan painting of ABBA recording at Polar Studios, apparently in 1978. I think it is based upon a real photo. Anyway, you can see the room is pretty dang big and while of course I don't know anything, it's possible that what people think is 'verb or gates or whatever on these drum tracks, I'd bet it's the "room" in the picture is what you are actually hearing on the drums. Every picture of Polar I've ever seen, there's like beautiful wood paneling everywhere.