I have the same question as was posted here

"I'm trying to understand what 'tuned feedback' means -- does this mean the signal enters a delay line that lasts one cycle of a certain pitch? (So, say, a 50Hz sound is a 20ms delay line.) Does this end up reinforcing that pitch when you hear the sound? (I guess it would reinforce multiples of the pitch too, but less so.)"

https://www.kvraudio.com/forum/viewtopic.php?p=1673572&sid=ae6a060ebaffea267114c1b6b5edde68#p1673572