Hi all. I was thinking about building a pedal that has an effects loop in between two effects. Do I need to use a special jack for that?
You'll need switched jacks. Inserting a plug in them breaks a contact, so if you wire them correctly, they would connect both tip terminals when there is nothing in there, and when you insert a cable the connection is broken and the loop is now between the 2 fx.
Paul
if space in the enclosure is an issue, you can also use a (switched) stereo jack and wire it like a insert cable. i believe the industry convention is tip is the output, ring is the input and the sleeve is of course ground. you need a special cable to hook up, but they're commonly available at music stores.