Carlo robelli bass preamp battery cover

Contact Sam Ash - That's their house-brand bass so they might be able to direct you.

 

Many of those house brand and budget brand basses use re-labeled generic electronics. Sometimes if you just troll ebay for a while you can find the same unit under other brand names, or even unlabeled direct from vendors overseas.

Might be worth ten minutes of scrolling through results for searches like "acoustic bass EQ" or "acoustic bass preamp" to get an idea of if there are any hits that look like the same unit, then you can focus in on parts for the names on the hits you find.

And/or post a close up photo of the battery box here and maybe someone can tell you if it matches a known generic part.

 

I have one of those basses.
It was a biotch when it was new ,.but
With time and work it can be a great instrument.




Ill look at mine and see if i can help

 

And another one with that bass

 

Hopefully Sam Ash can help you but I saw that same pre here:
Trinity River TO3CENGZ Outlaw Acoustic/Elec. Guitar, w/ 12 choice points | Tallman Instruments | Reverb

If you follow the link just scroll the pics to the right, you'll see this