This post delves into digital filters in AK4490 and AK4493 DACs used in W-DAC boards and provides extensive measurement results of the filters in time and frequency domain. This is not only relevant to these specific DAC chips and filters but general information on DAC digital filters from audio perspective. This is a practical approach – no poles, zeros, or formulas but lots of plots.
I bought a second hand M-DAC to have a well-known commercial reference in terms of measurements and sound. Obviously I needed to open it and see what’s inside. This is not a detailed reverse-engineering report but a glance inside with plenty of photos. Measurements are coming later.
I have stated some of my boards as “Arduino-compatible” as many other DIY and commercial electronics you can find nowadays. Simply put it means that you can develop Arduino programs (sketches) for that board with the Arduino IDE. Here are some information and references how to make a board Arduino compatible and what it means.
Many DAC chips and devices using those chip have user selectable options for digital filter response to fine-tune tonal characteristics. I will take PCM1794A used on H-DAC as an example and see what effects these filter types have on impulse and frequency responses. This is just scratching the surface of the topic by briefly introducing some technical effects that can be measured. Tonal characteristics are not discussed here; those are highly subjective and a topic of another post (or debate).