This preamplifier was designed as a stand alone portable unit, useful to control the signals generated by guitar pickups, particularly the contact bug types applied to acoustic instruments.
IC1A op-amp is wired as an inverting amplifier, having its gain set by a three ways switch inserting different value resistors in parallel to R4. This input stage is followed by an active three-band tone control stage having unity gain when controls are set in their center position and built around IC1B
P1,P2_________100K Linear Potentiometers:
P3____________470K Linear Potentiometer:
P4_____________10K Log. Potentiometer:
R1____________150K 1/4W Resistor:
R2____________220K 1/4W Resistor:
R3_____________56K 1/4W Resistor:
R4____________470K 1/4W Resistor:
R5,R6,R7_______12K 1/4W Resistors:
R8,R9___________3K9 1/4W Resistors:
R10,R11_________1K8 1/4W Resistors:
R12,R13________22K 1/4W Resistors.
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