Paul McGowan writes:
It’s easy to ignore–often criticize–the hard won victories of creative people designing leading edge technology. In fact, it’s one of the double edged swords of our abundantly-connected society that empowers readers with just enough information to miss the bigger picture. And this is part of the problem I find in helping unravel the workings of audio – and explaining the mysteries of differences in sound quality when none should be there. For when we wave our hand and suggest they should have done a better job, we gloss over all that does work well.
Take the relationship between a DAC and its source as an example. The architecture of the CD playback system was originally developed in the early 1980’s as an integrated device; a transport and DAC in one box. Within that box the optical drive supplies the master clock to the DAC through a variable timing mechanism; its variability essential to accommodating disc variations.
Variations in the master clock result in increased levels of jitter, reflected back to the listener in degraded audio performance. Armchair critics can suggest that DACs should have been designed as independent entities–instead of slaves to the source–and few would argue in hindsight. However, let us not wave our hand in a dismissive gesture. I find it more instructive to understand and appreciate the mechanisms behind the technology, even if they have flaws, rather than brush them off like a bothersome insect.
I suggested in yesterday’s post that different types of hard drives present music differently. I know this raises the eyebrows and hackles of many. But, I can tell you with no uncertainty that a solid state hard drive inside my Mac Mini server sounds markedly different than a mechanical one. Want more? The type of RAM employed matters too. How can this be? Data is data. Bits are bits. Right? Well, it’s true only in some cases.
A solid state hard drive sounds identical to a mechanical hard drive only when connected over a network, but different when powered by a computer connected to a DAC. Power supply variations in computers attached to DACs increase jitter levels in the same way that jittered master clocks in CD transports do. But, network connected storage is different. It is physically isolated from the DAC and the device feeding the DAC.
Jitter can result from differences in power supply and processing demands. Want to learn more? I would recommend re-watching our DAC designer, Ted Smith, in his series on what jitter is and why jitter matters.
Click here to begin.
