Harmonica players usually have a tough time getting both the right volume and tone without carting around a heavy custom amp rig. The Harp Commander III specialist Harmonica preamp from jfet magician Ron Holmes (http://www.holmeseng.com/) is a great solution, allowing harp players to DI into a PA (or amp) and have full control over their feedback free sound level and tone.
I was coming back from a jam session in a few weeks ago and my backpack split at a pedestrian crossing, dropping my Harp Commander III onto the hard bitumen. Initially I thought it was ok, but it the next morning I had an online gig and it was dead. On further closer inspection it appeared one of the xlr output volume controls had taken a hit, and it was off axis. I sent Ron Holmes a quick note, explaining what happened and that I was willing to take a shot at repairing it myself - something I would never have done pre-hackerspace soldering skills days.
Ron sent me back some detailed tear down/repair instructions, and part replacements specs which I ordered from mouser online. It was my first big desolder/repair/resolder and went pretty smoothly thanks to the detailed instructions from Ron, and over the shoulder checking from fellow TokyoHackerSpace members.
All back together...and ready to Boogie the Bitstream. Thanks Ron!
(fyi detailed info on Ron's design approach -> http://www.holmeseng.com/index_files/Page937.htm )