+ and - voltage for a battery?

basically Im making a guitar amp for a project and dont know how to get a positive and negative vvoltage probably + or - 12 or + or - 15 v i havnt decided yet.

Does anybody know a way of getting a positive and negative voltage off one smallish battery? I need the + and - for the op amps I am using.

Thanks for any potential help, cheers. Markdude

**broken link removed**

--uses two batteries...

How much power are you talking about here? Sure it's possible, build or buy yourself a switching power supply. But a "smallish battery" won't last very long driving a speaker, so you'd be looking at using multiple cells, in which case you may as well use something like Chris's picture. If the speaker is small and not very powerful, you could just use two 9V's. Better yet, use a single ended power amplifier like the LM386.

j.