Delay effects

The tapin~ and tapout~ objects work together to delay sound. The tapin~ creates a place in memory for storing a circular buffer of the most recently received signal. Its argument specifies how many milliseconds of audio it should store. Any connected tapout~ object accesses that memory to get the recent past of an audio signal.

Delay with feedback

The delay~ object does not permit its delayed signal to be fed back into its own left inlet. (You can probably imagine how that would make it impossible for MSP to calculate the correct signal, since you'd be asking it to perform infinite recursion: the signal plus the delayed signal plus the delayed sum of those two plus...). If you want to get delay with feedback, you need to use objects that are designed to handle that.