I don't know if it exactly fits your bill, Bill, but I'm surprised Rainer's chart missed some of the DD20's features. To respond to your needs:
1) The DD20 is stereo, both in and out. Depending on the setting, the DD20 will either generate a stereo spread from a mono signal (ping-pong or slow pan), maintain a stereo input as stereo output, or collapse a stereo input to mono.
2) The DD20 has a reverse delay. You can't throw a loop into reverse after it's been recorded, but you can record a loop and hear it play back in reverse.
3) Ostensibly the DD20 has 23 seconds of delay time, but I and at least one other looper (Ted Killian?) have commented on how you can rig it to get 46 seconds of delay.
4) No, the DD20 won't save audio, although it will save five settings.
If you want the DD20 to function as a looping device, you just set the feedback for maximum, play what you want into it, and turn the input off. For gradually decaying soundscape stuff, lower the feedback to taste. The DD20 does have a Sound-On-Sound function, too. And it's CHEAP! Under $200 per pedal. I own two, which not only gives me all of the above goodies, but some wicked patching possibilities when plugging one into the other. The internal clock is so stable that my two pedals will run in sync for a half hour at a long delay setting with no apparent drift. You can read more at:
and you can hear me using it on this cut (excerpt from "The Long Dance")
which is from the absolutely essential Loopers Delight Compilation, Volume 3, found here:
(and of course at CD baby).
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