I'm working on a mixer at the moment with built in delay and possibly reverb. The PT2399 datasheet example 'surround / delay' circuit has been changed around to create this plate style reverb. It still needs a bit of work as it's quite noisy, but as a start I guess it's getting there... Hear it for yourself;
A battery had gone rotten and melted one of the battery connectors on my Dan Electro spring king. It was a very simple repair, simply cutting off the old battery connector and replacing it with a new one, using some heat shrink tubing to shield the join. Opening up the unit, you can see how simple a design is needed to make a good-sounding spring reverb. Some people also mod this pedal with a PT2399 delay giving you a poor mans RE-201 space echo. Perhaps one day this could be a nice little project...
