I mentioned a little story in another thread regarding swapping out a Toslink digital connection for an asynch USB in front of a rock band members/engineers. They asked me what the improvements would be. I honestly could not describe it to them and had to keep telling them to listen. If I had to give them an answer it would have been, "lots of things can change."
High fidelity digital reproduction is a complex thing. What if I said the timing for a single audio sample changes if the last bit of the previous sample was a "1" and what follows it is a "0." But not in other occasions. Can anyone explain the audible effects here? It won't change frequency response. It won't change THD measurements unless you happen to be feeding the DAC these precise values.
As hobbyist in this field, we have an intuitive sense for a number of concepts in audio. We know about frequency response variations. We know about noise floor. We know about distortion (at least in gross amounts) of say, an amplifier. We know about coloration of speakers. We know about room effects. But what I described above?
The above also calls for appropriate measures to hear and instrument digital system fidelity. And of course, deep, deep understanding of esoteric aspects of this technology. This Saturday I am planning on teach a mini-class to my team at the store on this topic. I wonder how successful I will be in explaining these nuances. The topic an get as deep as one wants it to get!
I am not sure even I have mastered it. The USB to S/PDIF converter I use has a jitter simulator. It changes its clock to a lower fidelity one. Since that is under the control of the system, it also has a specific jitter spec. When I flip that switch, there is a noticeable change in audio. As I started this post, the changes are all over. It is not just "the highs are a bit less bright." More surprising is that the low quality clock is not so low quality. Its maximum jitter is 1.2 nanosecond. I can't explain the level of difference I hear relative to the number I just stated.
What is ironic is that when one thinks of "digital," the complexity of what I just described is the opposite of what comes to mind. Indeed, digital is thought to be perfect, and 100% clean. And here comes explanations of its performance that gives one a serious headache.
So what is the purpose of this post? Well, I am not quite sure . Other than saying that simple answers just don't do it for advanced digital audio reproduction. Saying it is all good because distortion is this low in digital doesn't either. Stuff is hard to explain, hard to characterize, and certainly very difficult to measure.
Comments?
High fidelity digital reproduction is a complex thing. What if I said the timing for a single audio sample changes if the last bit of the previous sample was a "1" and what follows it is a "0." But not in other occasions. Can anyone explain the audible effects here? It won't change frequency response. It won't change THD measurements unless you happen to be feeding the DAC these precise values.
As hobbyist in this field, we have an intuitive sense for a number of concepts in audio. We know about frequency response variations. We know about noise floor. We know about distortion (at least in gross amounts) of say, an amplifier. We know about coloration of speakers. We know about room effects. But what I described above?
The above also calls for appropriate measures to hear and instrument digital system fidelity. And of course, deep, deep understanding of esoteric aspects of this technology. This Saturday I am planning on teach a mini-class to my team at the store on this topic. I wonder how successful I will be in explaining these nuances. The topic an get as deep as one wants it to get!
I am not sure even I have mastered it. The USB to S/PDIF converter I use has a jitter simulator. It changes its clock to a lower fidelity one. Since that is under the control of the system, it also has a specific jitter spec. When I flip that switch, there is a noticeable change in audio. As I started this post, the changes are all over. It is not just "the highs are a bit less bright." More surprising is that the low quality clock is not so low quality. Its maximum jitter is 1.2 nanosecond. I can't explain the level of difference I hear relative to the number I just stated.
What is ironic is that when one thinks of "digital," the complexity of what I just described is the opposite of what comes to mind. Indeed, digital is thought to be perfect, and 100% clean. And here comes explanations of its performance that gives one a serious headache.
So what is the purpose of this post? Well, I am not quite sure . Other than saying that simple answers just don't do it for advanced digital audio reproduction. Saying it is all good because distortion is this low in digital doesn't either. Stuff is hard to explain, hard to characterize, and certainly very difficult to measure.
Comments?