My friend Pierre from Montpellier, France emailed me with this interesting EP-3 he purchased, apparently a late model Echoplex that looks like an EP-3 but has tube circuitry!! It uses a two 6EU7's and a 6C4, just like the EP-2. The circuit is most likely a revamped EP-2 on a printed circuit board.
Pierre emailed Bart Postlewait, Mike Battles apprentice and owner of MewplexFx.com for information:
"Hi Pierre, Thanks for your question about your EP3. That model is a Market Electronics made machine. Mike Battle built those by hand. He was concerned that the new solid state machines might not be as successful as the original tube ones so he converted some of them back to tube circuitry. They are very hard to come by and usually sound great!"
Here are some pictures of Pierre's Echoplex:
