Just a stab in the dark here…
Could adding an adsr or, just an ar circuit onto a reverbs wet signal create a reverse reverb/bloom effect?
Reverse reverbs are often a wet/dry mix of the reverse dry input I think?
But a bloom effect, absolutely.
Envelopes add a lot to modulation and effects. LFO via an envelope controlled VCA controlling frequency modulation is something I use a lot.
One of my buddys said its a bunch of rapid fire modulating delays. Definitely some sort of feedback loop. I wonder if for tape you ran the heads in playback-erase-record order, close together, and with the feedback signal from the rec input mixing with the playbacks you could do something weird