I picked up a used but mint Epiphone Archtop bass in the summer for an acoustic blues project I'm working with. It looked and sounded fantastic, with the typical modern Epi build quality. However, the stock piezo pickup by Shadow was an absolute piece of crap, scratchy sounding and feeding back at the slightest hint of volume, so knowing Jason Krivo's reputation for making pickups for archtop guitars and double basses I dropped him a line to see if he was up to the challenge: he was.
It sounds fantastic: warm, rich and true to the acoustic tone of the instrument.
Jason took various measurements from me and used a smaller gauge of cable than usual so I didn't need to drill a biggger hole than the one I had already put in the bass for a previous (failed) install. The pickup arrived with a piece of double-sided adhesive foam, which I cut to fit and the rest was an easy install, although I did do a dry install first to make sure everything fitted.
I even modified the pickguard to ensure a snug fit (didn't get the shape quite right on one side, but no biggie).
It wasn't cheap, but it really is a fantastic pickup that means I can gig without worrying about feedback, while still retaining the true acoustic tone of my bass. Jason is planning to add it to his line of products.