Although a colleague from Germany had not looked into the topic for a long time, I decided to point to the source of the power problems that caused him to hum in the sound. I figured out the board of this Chinese manufacturer. He has a typical error in power calculations. The transformer actually produces 7 volts of voltage. However, diodes with a very large drop in the forward direction are used in the rectifier. Therefore, the output of the first stabilizer remains a component variable. It goes further to the analog power of the DAC and then to the output.
The problem is solved simply by replacing the diodes with Schottky diodes with a very low voltage drop. This is verified by me in practice.
Probably the correct diodes were used in the prototype. But with a series in China, it is customary to reduce the cost by using cheaper components. In this case, it played a fatal role with sound quality.
The problem is solved simply by replacing the diodes with Schottky diodes with a very low voltage drop. This is verified by me in practice.
Probably the correct diodes were used in the prototype. But with a series in China, it is customary to reduce the cost by using cheaper components. In this case, it played a fatal role with sound quality.
O.K, I wil check! Will take a little time...
Hi Salar did you solve the hummm problem?
Did you make other fine upgrade on your DAC?
Best regards