[sdiy] Tube amp problem

[Justin Herrmann]

Hi, my senior design lab final project is to design a vacuum tube guitar
amplifier.  The output stage uses two EL34's.  The first time we
(our project group) powered it up, one of the tubes made a buzzing sound,
then it made some popping sounds and emitted flashes of blue light, at
which point we turned the power off.  We rechecked all the connections,
put in two new tubes (or valves), turned the amp on again, and one of the
tubes made a hissing sound, so we turned the amp off before anything could
blow.  I really have no idea what could be causing this.  Does anyone have
any suggestions?  You can see the schematics for all the parts of the
project at http://people.eecs.ku.edu/~herrmann/sdl/tubeamp.html

							-Thanks-
							-Justin Herrmann-