"Key signature" is a notational device. You mean "key".
A five second google search says Bb major.
Someones knowledge of guitar companies spelling determines what amps you can own. Really smart people can own things like Framus because they sound like they might be spelled with a "y" but they aren't.
Here's a better question, why would you wanna know?

I'm just kidding, I don't know
My Gear:

Epiphone Limited Edition '66 G-400 SG
Fender Standard P Bass
Ampeg BA115
Boss Metal Zone Pedal
Electro-Harmonix Memory Toy Analog Delay
Quote by jackblsdaniels
so why do you need they key? you dont need to notate it if ur singing :P

he may not need to, but it can be helpful to notate it