Regulated power supply ( parallel ).

This power is without compromise. It combines the performance of an unregulated power supply in the mid / high and that of a regulated power supply for the control of the subwoofer. Operation is simple, an operational amplifier is mounted as a comparator. It creates a reference voltage of about 18V (not critical) with precision zener diodes, decoupled by a capacitor tantalum. It creates an adjustable voltage divider to supply the input - the operational amplifier. It is weak against feedback in order to stay in line. The output of this op-amp control darlongton a transistor that will deflect a certain amount of current to ground, which will effectively cause a voltage drop in the resistors in series.

For proper operation of the power supply, using a 2 * 35V transformer, which gives us a quiescent current of about 200mA (depending on the value series resistors).

Here is the pattern of food:

View schema to enlarge it (right click)

The recovery was represented with a simple diode rectifier, but I recommend using a double bridge consists of fast diodes (BYV27) decoupled by small ceramic capacitors (680 pF).
The first two 25 ohm resistors can be advantageously replaced by a double self rising out of phase, equivalent series resistance.
It will deal with two trimmers to obtain 35V output. The power resistors (the 8W) to be detached from the circuit as they heat up during operation.

Nomenclature:
RT1: 2 * 35v transformer, 80 - 150 VA
AC1: Pont de diodes molded 8A
C1, C2, C3, C4: Capacitor 4700uF 63V chemical
R1, R4: Wirewound Resistor 25 Ohms 8W
R2, R3: 33 Ohms 8W Résistace wound
C5, C6, C8, C9 Capacitor 40V 47000uF chemical FRS
C7, C10: Capacitors 40V 15000UF chemical TFRS