http://www.diyaudio.com/forums/solid-state/164208-500w-pa-amplifier-limiter-4.html

http://www.diyaudio.com/forums/solid-state/164208-500w-pa-amplifier-limiter.html 

For B500 2x60vAC max, but I suggest 2x55vAC for safety operate.

Use two caps 20,000uF/75V with transformer 1500W 2x50VAC sec for stereo.

2x450W on 4R load

For about 120W/200W, 8R/4R use B500 pcb with two pair outputs on +/-60V rail voltage.