Car Power Supply for BA-1 or BA2?

[sheep]

How can I design a power supply from a car battery 12.6V?
Are they any examples?
I have an early Soundstream amp that Nelson designed.

 

[juma]

Here is a nice PSU that will generate +/-22V out of 12V - enough for 20W @ 8 Ohms:
http://www.diyaudio.com/forums/power-supplies/212945-boostor-ideal-companion-circlophone-move.html

 

[Chamberman]

There are a few SMPS supplies on Ebay designed for a car, here is one. It is probably higher DC rail voltages than you were looking for, but I know there are others on Ebay.