This project was released by mcds
To change 12V to +/-30V 250W mdcs used components from old ATX power supply especially BUZ11, diodes, transformer, choke and caps
Acoustic filter was created on NE5532
After first run we need select working frequency of MN3101 for it we use potentiometer 10k and setup max current 200-300mA (without amplifier TDA)
From car accumulator use other wire - minimum 30 Amps!
Author of this project used 250W ATX, for 2x90W he had about 70W free so he install flourescent light in a car

as he said - 100% working