Yesterday was my travel day. I had an early flight (6:20 am) and had to get up early – very early – to get to the airport on time. After dashing to the studio to grab my Oppo BDP-103 and some sampler discs, I got to LAX about an hour prior to my flight, checked my bag, and went through security. I sat on an aisle next to a couple of young women on their way to Dublin. How do I know they were going to Europe for a month long vacation? How do I know that one of them is recently divorced after 13 years? Because they didn’t stop talking during the entire flight…over four hours of non-stop chatter. I didn’t bring a set of headphones or earplugs.
It was a very hot father’s day in NYC. I took the local train instead of the express from JFK to Manhattan, which added 45 minutes to my transit but eventually got to the AirBnb place near the village. It’s on the 5th floor but very nice and air-conditioned. Thankfully.
While I was on the plane, I managed to get connected to the Internet and went through the numerous comments on the FAQ section of the high-resolution audio guide. Thanks for the help in reviewing and commenting on the content, wording, etc. I think the latest version is much improved although I’m feeling that there are more questions that need to be added to the list.
One reader asked about “resolution” as it applies to audio. A number of articles on high-resolution audio use a graphic analogy with pixel density and digital photos to show how increasing the number of pixels and the bit depth associated with each pixel results in a more realistic image. People get this comparison. But it’s a little tougher to grasp how a sound wave can be digitized and the impact of more samples and longer words.
First, we need to establish that “resolution” only applies to analog signals that have been digitized. There is no such thing as “analog resolution” as some writers have stated. Analog signals remain in the analog domain. The compaction and rarefaction of air molecules contain and convey sound. The electrical current and the alternation of voltages in a wire also represent the actual analog signal captured from a microphone. And so do the grooves on a vinyl LP or the magnetic “domains” on a length of analog tape. There are no discrete quantities associated with analog signals. The voltages smoothly and continuously swing back and forth at amplitudes that mirror the loudness of the original sound.
Resolution applies when we convert the smooth, continuously variable electrical signals into discrete packets of information at each sample time. We don’t try to “digitally” draw each waveform with increasing numbers of pixels. Sampling an analog waveform requires a steady stream of samples and a measurement mechanism to establish a value at each sample. As for resolution, the higher the number of samples and the longer the digital word associated with each sample, the higher the resolution.
We have to understand the concept of the Nyquist theorem, foldover/aliasing, quantization error, jitter, and the rest of the issues associated with digital sampling. If we raise the sample rate, the resolution of our sampling system improves…and we get higher frequency response, lower noise, easier filters, and double the amount of data to store and retrieve. Increase the word length and the result is a lower noise floor and higher dynamic range.
There are other frequently asked questions…send them along and we’ll refine that portion of the consumer guide to HRA. Got to run to the Metropolitan Pavilion and start setting up the demo system for tomorrow.