Feedback delay network is documented here : https://ccrma.stanford.edu/~jos/cfdn/Feedback_Delay_Networks.html
It seems to be like a lot of delay lines in parallel that are fed back into each other.
My skills in math/dsp are limited, so i assumed that the matrix at the top of the figure "Order 3 Feedback Delay Network." is just meaning that all sounds are summed up. But maybe i'm wrong ?..
There is a really cool fdn~ object in PureDatak, i'm trying to "replicate" it in gen~.
Of course as the pd one has inners guts that create (nearly) any number of delay lines, it's not the same, but it still can be cool i think.
I'm not sure how to do this. Is it like this ?