You mena a valve as in a glass state amplifying device commonly known as a tube statesside ? Hmm. Interesting.
Got a camera ? Throw some pictures up of this thing.
Tell you this, this is probably the most fucked up reverse engineering you'll ever do.
If you aren;t all that familoiar with these things there is a writeup here :
http://www.soundonsound.com/sos/feb98/articles/capacitor.html
I didn't read the whole thing, I just wanted somwthing on the dual pattern feature. Apparently they use more than one set of electrodes or whole two mike elements with a reflector. If it has a tube in it, if they went to all that expense then it is proibably the more expensive type, unless of course it is from 1963 or whatever.
One thing is for sure, it might be a bitch but if it has a tube (valve) in it, that it going to likely have three wires coming out of it, not pins. They are easy to break.
On this page :
http://en.wikipedia.org/wiki/Vacuum_tube
Look at the first one on the left in the first picture shows up. That is likely what you'll find in there.
Question : Does this power supply plug in the wall or just ruibn off 48 V power from an XLR connector ? Those little tubes do not pull all that much power. If the whole shebang runs on 48 V, you can probably current limit a power supply to the point where it is impossible to blow anything and then try connecting things. But I would higghlt suggest first being absolutely sur of which pins run the filament. THAT Is the most damagable thing in there and getting that valve/tube will be be very hard and not easy to install either. If you cna find out the ratings of the tube/valve, find out the current draw of the filament and make sure your source will not suppply more. If it runs off 48 V, it might be as easy as a resistor.
Like I said, this is liable to be the most fucked up reverse engineering you ever did.