Why DSD256? - An Explanation Almost Without the Jargon
Forty years ago some quaint little discs were released that would, we were told, revolutionise the way we listened to music, offering undreamt of naturalness and astonishing fidelity to the original performance or existing analogue master-tapes.
However from the moment they appeared there was considerable discussion about just how good CDs were. Nevertheless many music reviewers - who weren’t really interested in sound in the first place – and hardware producers took them to their hearts and LPs gradually disappeared to become a second-hand niche market.
Then in 1993 the worldwide web was launched, which meant far more people could share their thoughts. There were also those within the recording industry who recognised that the 16bit depth and 44.1kHz sampling rate CDs use was sonically compromised and sought something better, which in the first instance was dual-layer SACDs, where one layer held PCM (pulse code modulation) CD quality information, the other DSD64 (direct stream digital – or to be more accurate/pedantic, 1 bit pulse density modulation - which also enabled companies to make more accurate, analogue-like copies of tapes than PCM could offer), which means the sampling rate is 64 times that of a CD, but the bit depth is only one.
These appeared in around 1999 but never really took-off in the West, where it was left to smaller audiophile labels to carry the flag. Interestingly South Korea, Japan and some audiophiles never lost faith in them, so the majors licensed companies such as Esoteric and Tower to produce high quality remasterings from their back-catalogues and in some cases produced their own discs. Then, as interest in high-resolution sound grew, they started and continue to make a worldwide comeback.
The next step came with the expansion of the web and increased download speeds, which enabled companies from around 2008 to boast they not only recorded in high-resolution, but you could download the same quality files using Flac (which unlike MP3 doesn’t hack junks out of the files to compress them) from their own, or a third-party, website. To begin with these were mainly 24/96 or 88.2 with a smattering of DSD64, but as time went by 24/192 and DSD128 appeared, then there was DXD (24 or 32/352.8), DSD256 and relatively recently DSD512. But these were new albums, not remasterings.
So what has all this got to do with High Definition Tape Transfers, analogue to digital remastering and DSD256? Well as mentioned the doubts about digital sound led companies to try and improve it, using downloading. In addition hi-fi magazines such The Absolute Sound, had for years compared CD transfers of classic LPs with the originals and in most cases the CDs came a poor second and one of the world’s most highly respected recording engineers told me that CDs were the digital equivalent of a music-cassette. While those with LP collections would despair at the rubbish the majors churned out at increasingly cheap prices, where you could be forgiven for thinking the ‘remastering engineers’ didn’t know what they were doing, didn’t care and/or were using sub-standard equipment and software.
Enter Bob Witrak at HDTT, who realised that even commercial reel-to-reel tapes could be used to produce very high quality, more analogue-like, downloadable high-resolution remasterings that would also produce better sounding CDs.
To produce the digital masters he used and use’s the best software (presently Merging Technologies) and hardware, including cables and vibration control costing tens of thousands of dollars and a refurbished Studer 810 tape deck.
The reason that even commercial tapes are so good is that they are as close to the production-masters as the analogue era could get in the home, unlike LPs, which have always been compromised by the lacquer cutting process. But when he started in 2008 Bob only offered about 90% of his catalogue in 24/96, not DSD or anything higher (please see - https://www.enjoythemusic.com/superioraudio/guiltypleasures/0708/hdtt.htm). But unlike the majors and many of the independents, he moved with the times and as new formats appeared he produced these, upgrading the hard and software as and when needed. He has also started using master-tapes, which are in turn superior to commercial ones.
Now, of course, the majors have started issuing high-res remasterings, but these are all PCM, up to a maximum of 24/192.
As things stand the finest digital sound is produced by pure DSD512, where a performance is recorded in DSD256 and converted to 512, with no editing. The reason pure 512 is so good is that it sounds very much like high-quality analogue, with even more space and a greater dynamic range. This is down to a number of factors, but the way DSD works means the chain involved in it reaching your speakers is much simpler than PCM, so less digital processing goes on, so it sounds more natural and less tiring to listen to. In addition DSD has what is called very high frequency modulation noise, which again adds to the ease of processing and helps create a tangible sense of space and-analogue like instrumental timbres, this is present in actual performances or analogue master-tapes recorded in DSD and the higher the sampling rate the higher the frequency of the noise.
Up until now Bob only offered DSD256 when no editing was required, which he called by its accepted name, Pure DSD256. Now, rather than record in DXD, as he did before, he has quite rightly decided to transfer all the master-tapes to DSD256, if needed, edit in DXD and then convert back to DSD256 or less and other PCM formats, including CDs. And despite the two stage conversion the modulation noise isn’t lost (for those wanting more in-depth technical descriptions please go to NativeDSD - https://help.nativedsd.com/en/articles/3072297-dsd-512-but-how-is-it-created-and-why).
It is also the case that the higher the quality of the DSD master even when converted to PCM downloads and CDs, the result will be superior, so it’s a win, win scenario.
The difference this makes is tangible, irrespective of the quality of the original recording, the acoustic has a more walk-in quality, instrumental timbres are far more analogue and there is added presence; in essence it sound more real.
Personally I think that the Melos Ensemble album of French chamber music and the Frühbeck de Burgos Falla perfectly display these qualities and if you are only used to PCM and have the hardware to play them, I would urge you to try these.
But even if you don’t your PCM files and CDs will still sound better and while listening is highly subjective, I have yet to hear an ‘official’ remastering, be it on SACD or hi-res download that equals any of the HDTT catalogue.
Special thanks to Rob Pennock - Classical Source Online and Audiophile Sound Magazine
I gather all CDs that have been remastered have not bothered with DSD because it was much cheaper and more profitable to keep on making the same old same old 16/44 CDs
Well-written article, with good explanations of DSD. Thanks!