The world is DSD

Richard Murison, co-founder of Bit Perfect, writes, in the first issue of Copper, that the world listens to DSD. Quite a few of you have read that statement and asked me to explain what he means. After all, aren't CDs PCM based? And aren't the most popular high resolution formats, like 192/24 PCM based? Indeed, they are, so what's all this talk of DSD? Here's Richard's statement from page 16 of Copper.

The second thing you're going to hear a lot about is DSD, which may both surprise and disappoint you. After all, isn't DSD that odd-ball audio format promoted enthusiastically by super-serious audiophiles? It requires enormous file sizes and special hardware and software to play it back. It is seriously fringe stuff. So why do you need to be concerned with it? Well, the fact is that the principles which underpin DSD are hard at work in almost every digital audio device you own, from the cheapest DAC chipsets built into your mobile phone, to the most expensive stand-alone audio DACs. Even the ADCs which convert the recording studio's microphone feeds to digital audio numbers do so based on the principles that underly DSD. So, at some point, if you want to understand Digital Audio, you're going to have to understand DSD.

I certainly have no intention of stealing any of Richard's thunder, and he'll explain his thoughts in depth through his upcoming articles, but I figured a brief explanation of what he's referring to when he says "the principles which underpin DSD are hard at work in almost every digital audio device you own" is a valuable preamble to his column. All modern DACs and ADCs (Analog to Digital Converter, the opposite of a DAC) are Sigma Delta based converters. PCM, all 32 bits of it, is first converted to a format that's close to 1-bit DSD and all subsequent processing inside your DAC, from the lowest cost Audioquest Dragonfly to the over $100,000 whacko daco, is no longer a many-bit PCM process. And this has been true for many, many years. Fact is, when 24 bit DACs started appearing in the marketplace, chip designers were forced to move from straightforward PCM ladder-DACs to DSD-like Sigma Delta converters. Why? Because resolving 24 to 32 bit accuracy is next to impossible with part tolerances that have to be accurate beyond the abilities of manufacturers to produce. So, the next time someone tells you they only listen to PCM and haven't really played around with DSD, you can smile knowing they know not what they speak of.