Jonas appeared at the EBS Bass n' Drum event in Stockholm a month ago with this bass. I originally posted a thread ( http://www.talkbass.com/forum/showthread.php?t=209439&highlight=hellborg ) asking if anyone knew the builder/model (thinking it was a semi-acoustic bass). Thanks to the folks at EBS, who just sent me some better-quality pictures and some info. The bass is a solidbody custom Warwick. A complete one-off, built to Jonas' own design. Looks like it just has a single jazz pickup right against the bridge. The bass body is about 3.5" deep. I recently chatted with Dave Marks, another fine bassist who played at that event. He tried the bass and said "it's a heavy m**********r."