This month’s Roger’s Corner focuses on the topic of digital. First, I was very surprised to see that Roger wrote a chapter on this topic. Roger often told me that he had no desire to design digital equipment. He was very happy with his Sony CD players that he felt were reliable and easy to service. I will let those interested read the chapter to find out why audio playback quality was not part of that last sentence. I am so sure that it will go over most audiophiles’ heads but that is the life that the audiophile chose so they should rightfully live with it. However, Roger being the researcher that he was, he did have a very good understanding of the analogue to digital and digital to analogue conversion processes. Since the time this was originally written digital technology has evolved quite a bit and now many of us use computers, streamers, and other types of software and equipment for digital music playback. Nonetheless I think you will find that the basic principles still apply.
A Beginners Guide and Other Thoughts on Audio
Roger A. Modjeski
Chapter 6: Digital
To understand how digital works, we need to understand the process of converting an analogue signal to digital and then, turning the digital signal back to analogue with the hope that we restore the signal back to what it was when we began, which is not a simple task. When you digitize an analogue source, that music, although we hear separate instruments playing, as well as what notes and chords they are playing at different times, by the time it is all coming through a bunch of microphones and through a mixing board, it is now what I would like to call a time-variant voltage. Also, we are often told that second harmonic distortion is benign, and I think some people get the idea that a music system can hear the notes individual instruments are playing and then creates a second harmonic on these notes. The truth is there is nothing okay about that because if there is a great deal of second harmonic distortion, then there is a great deal of intermodulation distortion, which literally means one instrument is modulating the output of another instrument. This is what makes music sound muddy.
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