Bass Booster Stereo Preamplifier Circuit Parts:
P1_________________10K Log.Potentiometer (Dual-gang for stereo)
P2________________100K Log.Potentiometer (Dual-gang for stereo) (See Notes)
R1,R2_____________100K 1/4W Resistors
R3,R6______________15K 1/4W Resistors
R4_________________10K 1/4W Resistor
R5_________________22K 1/4W Resistor
R7__________________1K 1/4W Resistor
R8________________560R 1/4W Resistor
C1,C2,C5____________2µ2 63V Electrolytic Capacitors
C3________________470µF 35V Electrolytic Capacitor
C4__________________1µF 63V Polyester Capacitor
C6_________________47nF 63V Polyester Capacitor
C7_________________22µF 25V Electrolytic Capacitor
IC1_______________TL072 Dual BIFET Op-Amp
SW1________________DPST Switch (Optional, see Notes)
This preamplifier was designed to cope with CD players, tuners, tape recorders etc., providing an ac voltage gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets, the bass frequency range is rather sacrificed. This circuit features also a bass-boost, in order to overcome this problem. You can use a variable resistor to set the bass-boost from 0 to a maximum of +16dB @ 30Hz. If a fixed, maximum boost value is needed, the variable resistor can be omitted and substituted by a switch.
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