Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

13 thoughts on “A Final…But Not Last Word On DSD.

  • craig allison

    I see that I am not the only one who characterizes DSD/SACD as having a warm, smooth sound that is easy to listen to but lacks life in many instances. I will say as a super-fan that the Rolling Stones SACDs’ sound fabulous, master tape city, no question, having heard their stuff in every format and under a rather wide variety of conditions for decades to say the least.

    My comment about high rate PCM being more realistic but not necessarily easier to listen to appear to also find agreement in other comments here; more true sonically, but also a bit more clinical. Some folks will trade off clinical accuracy for ease of listening and access to the emotional content; that’s what the ‘tubes and vinyl’ thing is all about.

    Anytime anyone says “tests prove that people can’t hear the difference,” before I get sick, I always know that it can easily be the stress of the test circumstance that causes mis-perception, or lack of perception.

    Acknowledging the barriers to accurate perception that do cause far too many bogus reports, the only way to let your ears work the way they want to is to listen under familiar circumstances in a normal fashion. Since hearing is part of biorythym, anything that upsets normal biorythym is likely to affect aural perceptions. This is the exact platform that allows publications such as Stereophile to exist, and while I have my hang-ups with them related to grossly over-priced and sometimes questionably engineered products, if my postulate of “normal listening for correct perception” has enabled the mag to thrive all these years and help many, many listeners, there just might be something to it.

    • Admin

      Craig, you’ll be interested in the post I’m planning for tomorrow.

  • Chris Krueger

    Hi Dr. W,

    First things first: Massive thanks for fighting “the good fight” to differentiate science fiction from engineering facts. For some reason, the Audio world seems to be a place where the traveling medicine show hucksters have found safe haven in the 21st century. Bravo Dr. AIX! And thanks for asking us to use our ears and listen for the realities of tape hiss, vinyl surface noise, limited channel separation, encoding artifacts and sad, poor recordings. Trust our ears indeed!

    Now the great news: I’ve reconnected with audio after three decades, initially intrigued by the Pono marketing splash, and then drawn back into a relationship with recorded music again. As an EE and audio enthusiast, I did a “deep dive” into what had happended since 1985, with keen interest in the improvements in digital and the essential source material. Even on a modest budget, with more of my dollars (and sense) devoted to the source material, I’m able to have a playback experience that would have been impossible in 1985.

    Knowing from my training that the biggest improvements would come from starting with pristine source material, and then making sure the delivery chain did its best, I put emphasis on native playback/DAC quality (Fiio X5) driving a preamp free (one less link in the chain) direct/passive input amplifier (Acurus DIA) to the best speakers that suited my ears and budget (KEF Q and Sub). Then using tools only recently available (Onyx Apps/Faber Acoustical, etc.) to time-align, properly place and acoustically treat my listening space. Bye-bye turntable, ruby cantilever stylus, rack of components, moving coil head amp, 2nd Gen CD player, 66% interconnects, strapped Mono amps, power conditioner, and speaker overkill. Less is more.

    And most certainly, budget for HD source (the real stuff not Pono ponzi) and revisiting my CD collection to rip only the best AE masterpieces. This process has provided the vital ear-fuel that has re-ignited my passion for recordings. I am thrilling to re-discovery of old treasures, re-mastered classics and a whole new world of HD digital masters.

    I come full circle to another thanks — Thank you for helping me clarify, de-mystify and have this terrific adventure!

    With most sincere appreciation,


    • Admin

      Chris, it sounds like you’ve dialed in to the essence of great music reproduction. From source to delivery the simplest path is usually the best.

  • Chris Krueger

    Sorry… I meant for my last post to be a “general” comment, not related to the topical thread. Moderate as you see fit. CK

  • Dave Griffin

    My own experience with DSD, from files I’ve subsequently converted to PCM for use with my PCM only systems is that they come across as somewhat monochromatic, ie lack tonal colours, and yes somewhat smooth sounding as well. I’m surprised Craig finds PCM clinical; I find PCM to be nearest thing to live music I’ve ever heard. I’ve been into Hi-Fi for many years and believe that both my headphone and speaker systems are the nearest I’ve ever been to experiencing an accurate musical event.

  • Jeffrey Fritz


    Yesterday evening I was listening to the Steely Dan SACD “Gacho.” I was watching the VU meters on my Yamaha CA-810 amp. Between cuts, after a song ended, I happened to notice that the amp’s VU meters did not go to zero. Instead, they hovered at about the 200 mw level (with the amp set at normal listening levels.)

    Concerned that the amp could be oscillating, I pressed the stop button on the SACD player and the meters immediately dropped to zero. I restarted the SACD and watched the meters carefully between cuts of a different song set on the disc. Once again the meters dropped on the song fade, but stopped falling at about the 200 mw level. Then a fraction of a second before the next song started they fell to zero.

    The Yamaha CA-810’s frequency response is specified to 100 KHz (-1.5 db.) We know that the flaw of SACD DSD encoding process is that the noise and other encoding junk is pushed up above 20 KHz. My guess is that I am seeing this being reflected on the VU meters.

    I have tried five different SACD discs. Each had the same noise on it between cuts (about 200 MW at normal listening levels.)

    I have tried a number of CDs in the same player (Denon DVD-2910) and there was no measurable noise between cuts.

    The Denon SACD player has its ultrasonic SACD filter set to 50 KHz. (The other choice is to set the filter to 100 KHz.) The filter doesn’t eliminate the noise.

    I fed a DSF file from my Mac Mini through the Shiit Loki DSD DAC to the Yamaha and, no surprise, the HF noise was present.

    In theory, the ultrasonic filters in the SACD player are supposed to take care of the HF junk. In addition, the CA-810 has a high frequency filter that drops to -12 db at 20 KHz.

    Interestingly, while the SACD player’s ultrasonic filter did nothing, the Yamaha amp’s High Filter was very effective in removing the noise from both the SACD and DSD files. And, to my ears, there was little to no significant difference with the High Filter in or out. (Yes, I’m getting old!)

    This suggests that I can keep the High Filter on when playing SACDs or DSF files with minimal loss of information to my old ears. In fact, I can compensate somewhat for the lost highs with a boost of the amp’s treble control which, happily, is after the 10 KHz filter in the amp’s circuit.

    But now to the key question. Is this HF junk hurting anything?

    Of course it can be argued that any HF crap hurts the audio quality. It robs power and, at best, adds nothing. But, over time, will it harm either the amp or the speakers? My guess is that the amp won’t be harmed. It’s designed to handle frequencies up to 100 KHz and the junk is simply perceived and handled as just another audio frequency. However, this may be a bigger deal to the tweeters as they may try to reproduce the noise. My concern is that this will cause them to overheat.

    I started out as a huge SACD/DSD fan. The perceived difference in audio quality on SACD discs (more likely due to careful mastering than the format itself) was noticeable and remarkable. Now, I’m not so sure. I have reached the point where a well mastered Redbook CD or a well mastered uncompressed file has enough audio quality going for it.


    • Admin

      This is worthy of an entire post. What you’re experiencing is the ultrasonic noise that is inherent in the DSD format. As the frequencies of the SA-CD begin at 22-23 kHz, a filter at 50 kHz doesn’t help much at all. Whether we can actually hear the stuff or not isn’t all we need to consider…the electronics and speakers in your playback system CAN hear it and will try to work with frequencies that can only harm the sound and possibly the equipment. DSD at any rate is a sales and marketing phenomenon and nothing more. Read today’s post.

  • BrunoS

    Thank you very much for your series of posts about DSD. I personally much enjoy SACDs, as I find that they bring much warmer sound compared with CDs of the same material, and I own many of them. However, in the instances when I have been capable of comparing DSD and high-res PCM versions of modern recordings, I have always found PCM to sound more natural, closer to my experience when I am in a concert hall, while DSD is smoother. I can understand that some can prefer DSD as there is something “euphonic” to it, but to my ears it is slightly less accurate than high-res PCM.

    • Grant

      If someone tried to engineer a warm-sounding recording via CD, so you think they would fail? I doubt it.

      • Admin

        Of course, any sound can be put on a compact disc.

  • Robert Kelly

    Mark, your converter expert said, “The original SA-CD players and discs used DSD 64 and analog filters…and they were produced from analog and PCM masters.”

    I worked for the converter maker dCS during the time DSD was being developed and launched. I asked one of the senior Sony engineers I know who was involved in the DSD project about the early SACD release and he confirmed:

    “All TELARC recordings (except for reissue titles), all DMP recordings, San Francisco Symphony’s Mahler cycles, Yo-Yo Ma recordings, and following titles were native DSD made using Sony’s Blackline recorder, or Philips’ multi-channel recorder.


    Regarding A/D converter makers moving from 64Fs to 128Fs, the dCS 904 A/D converter was the first commercially available DSD A/D and is a 64Fs design. It was regarded as state of the art then and there are still many in use in studios around the world. Indeed your recent post about s recent study of perceptual differences between DSD and PCM was done with a dCS 904. The D/A converter in the current dCS audiophile products is a development of the 5 bit D/A used in the 904’s noise shaping loop.

    • Admin

      Happy Holidays Robert! It’s true that the Telarc and SFS Media recordings were made using native DSD techniques, but they represent a very small fraction of the SA-CDs or DSD recrdings that were made. The vast majority (85%) were transfers and not native tracks. Plus the outputs of the players themselves were filtered using digital means rather than analog to keep the cost of the players down…and they were done using PCM.


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