jazz bass preamp where I dont need the cavity routed?

Aguilar. Audere. 2 band EMG's.

 

Audere and J East make drop in preamps.

 

If you know what you're doing you can rewire most of them to use external power.

I've seen a variety of solutions including batteries in pouches on the instrument strap, multi-pin phantom power connections, and custom made TRS cables with pedal board mounted power supplies.

But it's a lot easier to just put in a battery box.

 

www.seymourduncan.com/pickup/blackouts-bass-preamp-2band-concentric

 

I find routing out under the pickguard the best for a J's battery.

 

You may be able to sneak the battery under the control plate. I have done that in the past. If you use standard VV pots and the Duncan concentric treble/bass pre mentioned above, you can probably make it work. The battery will be under the volume pots. Sometimes, depending on the body rout, you may have to widen the control cavity a touch to allow a battery to lie flat.

 

I have done exactly this. SD blackout preamp (stacked knob version), two volumes, battery fit in the cavity. It is a low-power preamp so I wouldn’t worry about short battery life.