Layout pre Amplifier with Bass Filter
The circuit is simple to set up and already has symmetrical power supply, the transformer must use 9-12 volts / 500ma with center tap In many cases the power source can be made by the power amplifier Just watch out for the limit supported by the voltage regulators.
The circuit has two pots, one for volume adjustment and another to adjust the filter cutoff frequency of 50 to 150Hz, if you need to install the pots in a panel, use shielded wires to make connections.
List Component
R1 8.2k – Grey, Red, Red, Gold
R2,R8 150k – Brown, Green, Yellow, Gold
R3 15k – Brown, Green, Orange, Gold
R4 1k – Brown, Black, Red, Gold
R5, R6 22k – Red, Red, Orange, Gold
R7, R9 10K – Brown, Black, Orange, Gold
C1, C5, C6, C10 10n/100V – Capacitor polyester
C2, c9 2200µF/25V – Capacitor electrolytic
C3, C7 220n /100v- Capacitor polyester
C4, C8 100µF /25V – Capacitor electrolytic
C11, C12,C14, C15 47n/100V – Capacitor polyester
C13 22µF/25V – Capacitor electrolytic
D1, C2, D3, D4 1N4004 or equivalent – Silicon Rectifier Diode
IC1 7912 – Integrated circuit voltage regulator positive +12 volt
IC2 7812 – Integrated circuit voltage regulator negative -12 volt
IC3 NE5532N or equivalent dual operational amplifier
AC Connector for 9 ~12 Volts transformer with center tap
IN Input connector for stereo audio
OUT Connector to the subwoofer amplifier
P1 47k – Potentiometer for volume control
P2 47K – Double potentiometer to adjust the cutoff frequency