This isn't quite a loop, but I think it's close enough. I want to be able to play something and have it repeated after a delay of about 15 seconds, then have it repeated again after a second delay of the same length, then not have it repeated further. I want this delay to be continuous: That is, I want to be able to keep playing and hear, mixed with what I'm playing, what I played 15 seconds ago and what I played 30 seconds ago. I have a Boss DD-20, which can repeat something after a 15-second delay, but only once. Or it can repeat something twice, but the first delay cannot be as long as 15 seconds. I had thought that I could use the DD-20's stereo delay as two mono delays: Connect the input to one channel, connect that channel's output to the other channel's input and use that other channel's output. But that causes the second channel to delay *both* signals, which means that the one in the middle gets played twice. Any other suggestions, other than getting a second delay unit?