Why would anyone be interested in a Direct Stream Digital (DSD) music format? Trying to explain the advantages of a high resolution 1-bit stream in a world of outspread Mp3 audio on one side and smugly high end audio on the other side, could become a Sisyphean task. Is it not just another digital format to improve sales of digital music? Absolutely not. So, why DSD?
A very natural thing
Analogue to digital converters (ADC) transform alternating current and voltage from microphones (which electronically represents analogue audio) into a binary stream of data. Both, PCM and DSD AD converters fulfill that task. In his interview, the pioneer of the practical DSD implementations Ed Meitner, gives his view of the initial DSD advantages:
“To convert audio into PCM is a very alien thing, whereas if you look at the convert audio into one-bit format, it’s a very natural thing. In any form of conversion, you will lose something. You have to choose the format where you lose the least, which means the format that’s the friendliest to audio, which is definitely DSD over PCM.”
To understand why DSD is “a very natural thing” we must first understand that all analogue to digital conversions start as a 1-bit stream. The method for encoding analogue signals into digital signals is called Sigma Delta Modulation (SDM). Digital data stream begins with Sigma Delta Modulation at a sample rate of 2.8224 MHz. The DSD process utilizes the Sigma Delta’s 1-bit output without any further processing, thus making SDM the only component of the entire analogue to digital conversion. By eliminating the re-quantization and decimation phases that would follow if the PCM format is required, the audio stays at one sample frequency (2.8224 MHz) and is only filtered and quantized once. The DSD encoding process is not only a simpler approach to A/D conversion, but also the source of a much simpler data stream than PCM A/D conversion. Consequently, a DSD data stream retains more information from the analogue waveform then either of the PCM encoding procedures and is therefore “a very natural thing”.
We must also consider the simplicity of format options. Conversion of a DSD master to a 16 bit 44,1kHz CD is a simple and natural process. Dividing a DSD sample frequency (2.8224 MHz) by 64 gives exactly 44,1 kHz. On the contrary, a 24bit – 96kHz PCM studio master (that was actually also DSD at the beginning of the A/D conversion), “unnaturally” downsampled to 16 bit 44,1kHz will definitely become a “digital mess”.
Until recently, DSD recordings were available only on SACDs. A good number of SACD players convert DSD recordings to PCM prior to analogue conversion and a lot of SACDs were originally sourced from PCM masters. The whole project was doomed from the beginning by a dilettante mixing of formats and a greedy concentration on selling “a new disc” to audiophiles. The result – there is no result. DSD masters were actually hidden among the digital conglomerates on SACD’s. Audiophiles were not impressed, digital music experts were confused and nobody really knew what we were listening to.
But now original DSD downloads are available. Your PC can be configured to stream DSD directly via USB (DSD over PCM using DoP) to a universal D/A converter capable of PCM and DSD conversion. Officially, we are still unable to rip the DSD layer from SACDs, although the unofficial procedure via a modified Sony PS3 shows that some DSD layers on SACDs are truly remarkable.
Regular visitors to concert halls, familiar with the sound of acoustic instruments, shall be promptly addicted to musical reality available from DSD studio masters. Serious music lovers and audiophiles can now download the original DSD recordings from www.nativedsd.com
Native DSD Music offers DSD Masters, sourced from DSD session recordings as early in the production process as possible. Sigma Delta’s 1-bit output without any further processing (unless specified otherwise) is what Native DSD Music offers to their customers.
After 32 years of Red Book (CD) domination and 15 years after the introduction of Scarlet Book (SACD) optical discs for DSD audio storage, 1- bit Direct Stream Digital can finally be played back from a hard drive. Audiophile Linux fully supports DSD playback. Do not hesitate to try it!