Grounding 9v

[Hilikus]

This is the last dumb question I ask I swear  :?  ! . I'm building "eighteen" from Runoffgroove, and only the +9v connection is specified. Do I ground the negative 9v lead ( I read there are some cases where you don't ground it..?)?

Thanks for any help!

[aaronkessman]

generally with effects boxes you ground the negative side of the battery through the stero input jack so that you disconnect the battery when there's no cable plugged in to save on battery life. but yeah, for the most part, negative terminal goes to ground. only on certain old effects can it go reverse polarity.