What is this LFO source?

Hey guys,

can you tell me which source this symbol is describing?
I couldn’t find anything in the manual:

AFAIK it uses the current output/signal level of the synth as a modulation source (sort of like an envelope follower). If you turn it on and alternate between playing one note and two notes together, you can hear how the two notes drives the modulation higher.

(I wish you could select a tape track as a source for this, to get ducking effects… alas)

Blimey, I’ve had the op-1 for years now and don’t think I ever figured that out. Nice one @raigan!

Selecting a tale track as a source would be rad! They need to implement that