The Boss DM-3 was the last analog delay pedal (so far) produced by Boss. Apparently it differs from the DM-2 by having a noise reduction circuit and an additional filter. 20ms to 300ms of delay time is on tap here. The pedal will work on 9v power but the LED will not: ramp it up to 12v power to get the full light show. The knobs are:
Repeat Rate - delay time (turn counterclockwise for longest time)
Echo - mix knob
Intensity - feedback
The DM-3 doesn't sound as bright as the Ibanez AD-9 in use. With the repeats cranked to 300ms and the intensity up, mine still won't feed back on itself. It will start feeding back at lower delay times and has the tendency to self-oscillate rather quickly.
Overall this is a good all-round delay pedal. Single notes don't get swamped and it's got enough 'mush' to it for my chordy spacerock floaty rubbish. It's also very good as a short delay pedal going into reverb or delay pedals with a longer delay time.