So I just installed a Bassmods two band preamp in one of my jazz basses. It sounds really good but there's one problem. The preamp module and wiring take up so much space in the control cavity that there is no room for a battery! My first thought is to add a battery box to the back of the bass. How difficult is this to do? I'm not really crazy about the idea of cutting a hole in the back of my bass! The other option would be to put it under the pickguard but that would make change the battery a bit of a pain.
Putting it under the pickguard would be simpler and more aesthetically pleasing. You only need to change the battery once a year or so. Routing for a battery box will require a handheld router (Preferably a plunge router, but it is not necessary.), a pattern-follower bit, and two templates. One for the cavity, and one for the recess.
Well I decided not to use the preamp in the bass I was planning to put it in. I just don't feel like hacking in to the body to make a place for the battery. Wish I would have known before I bought it that the Bassmod preamp is too large to fit the control cavity! I have another jazz body laying around that has a battery compartment in the back. Maybe I will use that as an excuse to build another jazz bass. Otherwise I will just sell it.