10x TDA1543 NOS DAC


Posted on Feb 7, 2014

In supply section after bridge rectifier and smoothing capacitor is used common voltage regulator LM317, which has with R1 and R2 adjusted output voltage about 8V. Supply line goes through inductor to DAC chip for theoretically lower HF interference which goes on the power lines. DACs have current outputs which are converted to the voltage outputs with the aid of resistors R4 and R5.


10x TDA1543 NOS DAC
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Sometimes is used circuit with operational amplifiers combined with low-pass filter which is much complicated and can introduce distortion in to the sound. Low-pass filter which is used for removing sampling frequency unfortunately introduce distortion on high frequencies. Sound is then more flat. Because DAC doesn`t have symmetrical power supply, that we must use capacitors in series with the outputs. It`s desirable to use high quality capacitors with sufficient capacity. It`s not recommended to use electrolytic capacitor. I used foil capacitors with 10uF value which are connected between outputs and output connector. They are placed out of board and they are not drawed in a schematics diagram. Output must not be too much loaded and should be connected to input of preamplifier or power amplifier with input impedance at least 10 kiloohms. It`s possible to have separated supply for DAC from independent winding of power transformer for better isolation between S/PDIF decoder and dac with changing voltage. Voltage regulator and DACs must be cooled with a small heatsink! Transformer must be dimensed for current 0. 5A. We are placing components on board from smaller to bigger. We begin with SMD components and next with normal parts. We must mount small heat-sink on the DACs otherwise they overheats and can burns (my own experience). I attached heatsink with two small springs hooked to four pins soldered to the board. For I2S...




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