Measuring MCK (System or Master Clock)

Another signal line that is required when using the I2S connection is the system clock (MCK or SCK). This runs in the many MHz range so you need a "real" scope. Another diyer, jkenny, took these measurements of his Musiland 01-US. The system clock is the clock that is fed to the DAC and all other signals are based of this clock signal

The picture below is for input signal with 44.1KHz sample rate. If one divides the frequency by the sample rate, 5.71Mhz/44.1Khz=129. System clocks are designed at 128x, 256x, and so on. Thus from this measurement we find that the Musiland device is running its master clock at 128fs

Why is this important? Because DACs are designed to run at a specific range (range of fs) for the master clock. If you operate the DAC outside this range, the DAC performance may suffer



The following picture is for input sample rate of 96KHz