Portable tube pre-amp for the covert recording of live concerts

In college we were on a mission, to record a live show in Chicago with the best audio quality possible. For this reason i developed the small portable tube pre-amplifier shown here.

This amplifier runs on 12 AA batteries (in a separate battery pack) and should last 3-4 hours. Works well with microphones, electric guitars, and would be great in any portable/mobile application.

I recently have posted the schematic here and photos here.

Enjoy!