FBC let's you add your own effects into the delay line so that you can build any delay you like. There is a send node and a receive node (entrance/exit node) with the effects chain sandwiched in-between them. To use, drop FBC-S in the device rack first and FBC-R second. Insert any audio effects you like in between them. On each of the node devices, you must send configure the audio routing to point at the other device in the pair. Then you can safely turn off the "Panic!" button that mutes the outputs. Be aware that the feedback can still get out of hand quite quickly, so gain staging within the chain and with the "Feedback" knob may be required. Distortion plugins and anything that will resonate specific frequencies are quite prone to creating explosive feedback loops.