This Hi Fi stereo preamplifier ambit is congenital with TDA1054 IC from SGS. TDA1054 is a 16-pin DIL amalgamation and integrates 2 abstracted preamp circuits. It is a low babble preamp with little or no botheration in the architecture process. The aboriginal bisected of the ambit (IC1a) it has an ascribe acuteness of 3 mV and has a abundance alteration composed of C5, C3, R6 and R8. The bass arresting advancing from phono ascribe is amplified while the aerial arresting is attenuated.
The alternative of the ascribe arresting sources is done with about-face S1. P1 and P2 are parte of a bifold potentiometer. They ascendancy the aerial tones and bass. There is no accident of overdrive in ambit due to the acquiescent attributes of the complete control. P3 controls the aggregate of the arresting fed to se additional allotment of the ambit (IC1b) which functions as an operational amplifier.
P4 controls the antithesis amid the larboard and appropriate channels but in the schematic is apparent alone the preamp for one channel. Both approach accept a accretion of 24 at the average ambience of P4. If P4 is set to one acute end, the accretion aberration amid the 2 channels is about 12 dB.
Source : www.electroschematics.com