Power Amplifier Auxiliary Powersupply

The PAAS unit is a simple board that provides a dual 12V/1A supply to power the DC detection, output relais circuits on the Power Amplifiers and the the analog signal conditioning circuits on the ADDA analog I/O unit. The +12V and -12V are used in  cascade  to form the 24V supply for the Amplifier Fan COntroller unit that drives two 12V fans in series.
The advantage to put the two fans in series in stead of in parallel is that both the positive and the negative supply are equally loaded and there are no fan return currents in the analog ground path, that I want to keep as clean as possible.
There is also a TI swith mode powersupply module PTN78000WAH on the PAAS unit that provides a 5.5V/1A output to power the TAS3208 audio DSP EVM and provides the power for the ADDA audio I/O module low voltage logic supplies and audio master clock oscillator.
As the schematic shows is it a straigt forward rectifier plus buffer cap topology with L7812 and L7912 regulators for the stabilized positive and negative 12V supplies.
An additional TPS76850 powered from the PTN module provides a low noise regulated 5V0 output but I decided to place a separate 5V regulator on the ADDA board so it is not used.