| BEFORE you take out the original tube, draw on paper how it's positioned, what it looks like in there. when you take it out, you may well find that the socket it plugs into has lots of holes and the tube can be plugged in many different ways. only one way (the original way) is correct, any other way could go boom.... and as you pull it out and see what the pin layout is and where the label is on the glass of the tube itself relative to the pin layout, draw that also, so your replacement tube (which prob looks surprisingly different but should have the same type of pin layout) will be put in the same way, not turned so it dies or goes boom.
Yes, I'm trying to scare you, and in that device the plate voltage is relatively low, but it's still vital to not breaking things, and when you get into bigger power amp tubes like in a guitar amp, you'll find that putting it in wrong can actually be very very serious....
other than that, look up somehwere about how ax, at, au etc relate in their output levels etc.
Cheers,
Don |