I attended the CanJam Singapore 2023 on 25 March and met up with Rob Watts, independent design consultant of Chord Electronics. We had a conversation, not an interview, and it made me rethink about the future of digital audio and the relevance of the analog medium (tapes, vinyl).
I last met him during the CanJam 2018 so I started by asking him what has changed over the last 5 years in his field of digital aaudio. He responded that he is trying to close the gap from live unamplified sound to reproduced sound and make it much closer to the original. He asked himself two questions:
- What level of transient reconstruction accuracy do we need?
- How small do we need to make noise floor modulation so that it becomes inaudible?
For question 1, his research led him to the conclusion that, it does not matter how small the transient timing error is, it is still audible. So he will continue to improve on this by increasing the number of taps which will better reproduce the timing information of the source signal.
For the second question, he shared more insights because it sounded (pardon the pun) unbelievable that he wanted to achieve a noise floor below -301dB. His listening tests confirmed that test subjects are able to detect noise floor modulation even at such insane low levels. He further explained that the noise floor moves up and down in sympathy with the music, which blurs the instruments. His conclusion is that this error must be further reduced to zero or near zero. Not only is it has to be zero amplitude error, it has to be zero phase error. What this means that the amplitude and phase of small signals need to be perfectly reconstructed.
At this point, my mind was thinking: if we are all trying to achieve a zero-error digital audio reproduction, would it mean recording on analog is better? Rob promptly said no, because analog medium has its own issues. For instance, reel-to-reel tapes have bias frequency which affects the transients, which is the reason why analog sounds “soft” and warm. “Analog does not sound like unamplified sounds. It’s nice, warm sounding, comfortable, but it sounds nothing like a live orchestra without any amplification,” he said.
“I’m not trying to chase an analog sound. I’m not trying to make a warm sound. I’m trying to make it musically involving and emotional, by capturing the original sound.”
He also started making his own recording using his own equipment so that he is in control of the whole recording process. Through this, he can compare the live performance with the digital recording and have better understanding between live sound and recorded sound. It’s about chasing the errors and making it smaller and smaller towards zero, which is impossible. He thought that if the error is small enough, we won’t be able to hear it, yet he found out that we can still detect it. This realisation means that there are opportunities to improve the sound quality and performance of DACs.
Closing Thoughts
Back in the past before digital audio, all recordings were done in the analog format, which is the original medium. It does not mean that it is how the live performance sound like – we know how “horrible” those Shellac recordings sound – but it is the most authentic version that the recordings were captured using the available tools.
With digital recording technology, it is capable of capturing a much greater dynamic range with better transient and more importantly, lower noise. While purists argue that digital audio does not translate 100% to analog signals, digital technologies developed over the years are closing the gap. Most digital proponents claim the audio differences are too small to be noticeable, and for those who know otherwise, Rob Watts is working on reducing the digital errors to an imperceptible level.
Analog vs. Digital
This conversation validates my vinyl collection approach, which is to collect only recordings produced during the analog era that uses analog equipment. These recordings may contain imperfections, but they are the product of their times. It fascinates me that I am able to listen to records pressed in the 1950s, exactly how it sounds like 70 years ago. For pressings in the 1970s and 1980s, I have to say that the sound quality is really better than the original CD masters. But from the 1990s, with better digital audio production, vinyl copies at best match the digital versions, because these albums are made for digital.
The digital audio landscape will continue to uncover innovative opportunities that closes the gap between true analog signals and digital recordings. And thanks to passionate people like Rob Watts, DACs will get increasingly better and affordable.