Hi I m just starting the build for this and really inspired by the videos - can i check, I've looked at the data sheets for the 79L09 and the 78L09 they seem to be suggesting that the 79L09 should take a negative input  -12volts and the 78L09 should take a positive input +12volts. This is the opposite to the schematic. Can you confirm which way around these should be, please? Thanks