Dr. AIX

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.

32 thoughts on “An Invitation and Challenge of My Own

  • February 17, 2015 at 2:57 pm
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    From “Perfect Wave” component to “I can’t listen to PCM”, we have two oxymorons supported only by fan base.

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  • February 17, 2015 at 8:15 pm
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    I wish you all the luck but those mentioned will never submit themselves to a test in which they could be made to look foolish. A couple of them (you know who) will claim the test would have no validity in any case since the HD files are not DSD.

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  • February 18, 2015 at 4:52 am
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    Mark: I have to say that reading your posts has been one of the best things I’ve done in furtherance of my audio “addiction”, a “condition” I’ve had for 40 years or more. Yes, I have a turntable and still play some LPs, but only if I can’t find the same stuff on Tidal (especially all my old ECM recordings which aren’t available on any of the streaming services). Using ECM, as an example, many of their old (1970s era) LPs are available on HDTracks as digital downloads. In many cases HDT makes it clear that they are CD quality only, but in some cases they are 96/24. I really struggle whether I should buy the 96/24 HDT version (for $15-20) or just buy the MP3 version from Amazon. Frankly, since reading your posts, I’ve opted, most often, for the MP3, when considering recordings made originally on tape. If I’m going to spend that kind of money for High Res Audio, I want it to really be Hi Res. Do you agree with my choice?

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    • February 18, 2015 at 11:09 am
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      I would never purchase a lossy file no matter how good it sounded. You’re better off to by the CD and rip is yourself.

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    • February 18, 2015 at 1:56 pm
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      Mark’s right, best option is to buy the CD and rip it to your computer.
      Alternatively if your LP’s are in mint condition and you have a quality turntable setup you can do a very high quality digital recording using a free program called Audacity.
      Before my retirement move I recorded my 150+ LP collection to 44/24 flac files. Took some time but except for the occasional click/pop the playback sound is incredible.A good option if you can’t find the CD.
      EEBay is a great place to locate used CD’s.
      OR Chicago Digital in Oak Park IL has about the largest inventory of used CDs in the country. http://www.chicagocompactdiscs.com. Owner Chris is a great guy and friend since he opened his CD only store in 1985

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  • February 18, 2015 at 5:12 am
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    Hi Mark,

    I took the test with your tracks and with the best gear I have available to render HRA: Benchmark DAC1, Violectric V281 headphone amp, Sennheiser HD800 / Audeze LCD-X headphones. I repeated the test 3 times and different days of the same week.

    I was able to consistently tell the mp3 from both CD and HRA (more than 90% of the time), but failed to reliably tell the difference between CD and HRA.

    It was easier telling the difference between mp3s and CD/HRA by identifying the limits of the mp3s, and in specific passages that made the difference obvious. But even the same passages that revealed the shortcomings of the mp3 files didn’t help me much when it came to telling CD from HRA. I was several times totally convinced I had heard a clear difference, but I was actually wrong all those times.

    If hearing the difference between CD and HRA isn’t something obvious, even in a quiet room and with some of the best headphones available, HRA downloads can’t possibly be worth the extra money. And if it’s necessary to be “taught” to hear the difference, as Cookie Marenco suggests, then where’s the experienced and evident qualitative difference Neil Young is talking about?

    I am willing to give it another shot with future recordings, but I have to say that I’m not highly motivated to pay extra for a difference I can’t immediately perceive or enjoy.

    I am willing to wait for a recording made with HRA capable mics (like the Earthworks QTC40/QTC50s or DPA 4004s) and a JAS compliant mic preamps (like a Benchmark MPA-1 or a Millenia HV-3C, etc.) and A/D converter, and from an A/D converter that can output two different yet simultaneous signals in two different sample rates and word lengths – like the Benchmark ADC1 -, but that’s as far as I think I will go.

    I’m willing to buy 24/96 downloads for the sake of it, but not willing to pay more than the cost of a CD. The 24/96 recording doesn’t cost more to make than a Redbook CD recording, and the download is way cheaper than the physical media with all its associated costs.

    For now I’m sticking with the premise of the best possible provenance, that’s where the real qualitative difference is going to come from, and that’s a qualitative difference I can clearly identify and totally enjoy.

    Cheers!

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    • February 18, 2015 at 11:11 am
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      Thanks for the very thoughtful post…

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    • February 18, 2015 at 12:28 pm
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      Hi Camilo, thanks for the interesting post. Hopefully you would pay for multi channel, though, because it passes your test of “immediately perceive or enjoy”. The trick, of course, it to get the playback equipment. 🙂

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      • February 18, 2015 at 5:24 pm
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        That’s right, the trick is to have the money to buy a 5.1 or 7.1 system with decent speakers, and have enough room and tolerance for them interrupting your living room.

        I’m personally a stereo dude, and I’m still more convinced by a good binaural recording than surround, but well done binaural recordings are very few, and not very likely to become more. They are also not consistent in quality.

        Chesky records have put out two or three very well achieved and convincing binaural recordings, but also several that are rather disappointing, like the latest one with Xiomara Laugart. I’m not a fan of Xiomara’s music, but I am interested in the binaural series that Chesky has been puting out, and to see where that is going as well as to understand a little bit more about how that particular recording technique works in different musical settings.

        I know that Mark, Morten Lindberg and now Jonas Niederstadt (from Carpe Diem Records) have made some really compelling multichannel releases, but I would hope for Edgar Choueiri’s Pure Stereo development to be improved and reach the market with a smaller price tag in the future. I would of course get a 5.1 system if I had the money, but that’s not likely to happen in the very near future. A set of 5 Genelec 8240As and one of their subs would be awesome.

        Cheers!

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    • February 18, 2015 at 5:34 pm
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      Hi Camilo, i always come back to the same concepts when this subject comes up. Skipping the issue of provenance, I bet we can agree that hearing a fine original master tape at home has long been one of the ‘holy grail’ items. Yet we both know that CD and LP are mediums which clearly have signal capacity limitations; neither can or ever does clone the master tape.
      I’ll use SACD here as our ‘hi-res’ medium analogy. I have heard the music of the Rolling Stones countless times, from every medium, in countless environments, differing playback systems and states of consciousness over the last 50 years. I also have personally made top-grade LP and CD from very dynamic master tapes, so my ears work, don’t question that. When I play the SACDs’ the Stones released, I AM SURE that what I am hearing is the master or indivisibly close. Wider bandwidth, more spatial dimension, true to life vocal sound, improved micro/macro dynamics,and sheer transparency, all of these qualities smoke the CD releases in the same way that a proper hi-res transfer will too. Yes, one could be fooled under test circumstances that simply don’t have enough content to reveal, or are unfamiliar. But my experience will duplicate itself every time you compare music with which you are intimately familiar, comparing standard CD issue to Hi-Res. The only other thing that complicates is that magnetic tapes deteriorate no matter how carefully stored, so an LP or CD made when the tape was fresh may well be in better shape than when a hi-res transfer is made at a much later date. Thanks.

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      • February 19, 2015 at 9:54 am
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        If the transfer of the original Stones master analog tape was also transferred to a CD, you would be unable to tell the difference between the CD and SACD. In fact, that comparison (with a brand new recording that would greatly exceed the fidelity of the Stones projects) was done and written up in an AES paper…no one could tell DSD and PCM apart.

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    • February 18, 2015 at 7:17 pm
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      “I was able to consistently tell the mp3 from both CD and HRA (more than 90% of the time). . . .”

      How were the MP3s encoded, and at what bit rate–128, 192, 256, or 320 kbps? Indeed, it seems bit rate is a crucial factor. It’s easy for me to identify a lower-quality MP3, but I find it much harder for higher rates, especially 320.

      Thanks!

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      • February 19, 2015 at 9:58 am
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        The MP3 files were made at 256 kbps.

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        • February 19, 2015 at 6:44 pm
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          I wonder if he’d be able to hear a difference between 256 and 320, or 320 and CD.

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          • February 20, 2015 at 9:14 am
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            It’s really hard to hear the difference between a 320 kbps file and a CD.

  • February 18, 2015 at 11:38 am
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    I agree with Michael Fremer that vinyl LPs have more dynamic range than all CD flormats !! Digatal audio played thru. high end audio systems still sounds tin can like compared to analoug master tapes and vinyl.
    Comparison of this fact is most often done on low Fi systems and the diferance is not easley noted. Do your self a favor and audition audio at one of the conseumer electronic shows where you can here some High End audio systems demoed and keep an opem mind.

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    • February 18, 2015 at 1:34 pm
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      Agreeing with Mr. Fremer that vinyl LPs have more potential dynamic range than CDs would ignore the basic facts about these formats…but if the sound of vinyl LPs lights you up, keep on enjoying them. Your personal preferences doesn’t alter the specifications of these formats. The dynamic range of a CD can reach 93 dB…analog tape and vinyl LPs top out at around 60-70 dB.

      I’ve been to just about every audio trade show as a participant and sat in plenty of demo rooms listening to vinyl LPs, analog tape, SACD, CDs, Blu-ray Pure Audio and high-resolution files. My own personal preference is for less distortion and more accurate sound…something that vinyl and analog tape don’t do very well.

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      • February 19, 2015 at 12:08 pm
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        Live music has several orders of distortion as precived by the human ear. Pure analog recordings also includes includes most of these distortions to a lesser degree in some cases and never perfectly. Theese include sound bouncing all over the place rendering a more life like sound. Digatal recordings seem to dampen out most this preception of three dementoinality. I have discovered that individuals who here pure analog as distorted or irritation suffer from some degree of tenities (see an MD who is an Audiologist for a definition) are not bothered by digatal recordings as much. This is relatively common and unfortunate, most people are not aware of this problem as one person in five suffer from this!

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        • February 19, 2015 at 1:36 pm
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          Imagine a live performer playing and singing 10 feet in front of you…without a PA system. There is no distortion associated with this type of live playback AND digitally recording captures and delivers the actual sound better and more accurately than any other format. Digital doesn’t “Dampen out” anything.

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          • July 18, 2015 at 5:39 pm
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            Actually, the dynamic range of CDs is 96 dB, as each bit corresponds to 6 dB of dynamic range (16 x 6 = 96). If using dithering, the dynamic range is around 120-150 dB.
            The numbers I’ve seen (45:06 into this video https://www.youtube.com/watch?v=BYTlN6wjcvQ as well as http://wiki.hydrogenaud.io/index.php?title=Myths_%28Vinyl%29) says analogue tape has a dynamic range of 74 dB and vinyl around 80 dB. And we should also remember that (as far as I know) NO recording in history uses even 74 dB of dynamic range. 96 dB is basically overkill.
            It is true that certain CDs are mastered poorly, and the SACD version (or Hi-Rez or even vinyl) is mastered much better. A guy like Michael Fremer would probably even prefer vinyl over the master tape in a blind listening test. That’s of course fair enough – we all have things we like, but it seems to be more vinyl glorification than anything else (“if it’s vinyl I like it, if it’s not vinyl I don’t like it).

          • July 19, 2015 at 11:50 am
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            Thanks for the post and links…although the information is somewhat off the mark. The theoretical range for CDs is 96 but with dither they only get to 93 dB, which is more than enough to handle virtually all releases as you say. Using noise shaping on a 16-bit CD can theoretically push that higher but nobody does it and there are no systems to play it…so why bother talking about it. Just move to 24-bits. Mr. Winer makes some good points…largely in keeping with my own assessments that PCM digital (even 44.1 kHz/24-bits) is better than analog tape and vinyl.

            A first rate analog tape can get to between 60-72 dB or the equivalent of 10-12 bits in PCM. The claim that no recording in history uses even 74 dB of dynamic range is incorrect. I’ve measure plenty that do…including most of my own. I don’t use compression and I don’t master my recordings.

            Mr. Winer doesn’t believe that high-resolution is important…that’s his opinion. I do.

          • August 25, 2015 at 10:26 am
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            Okay, so there are apparently recordings with higher dynamic range than 60 dB. Nevertheless, what I like about your writings and Ethan Winer’s writings is that they call to sensibility. Why do we obsess over such unimportant issues as X dB more dynamic range or a higher sample rate when the 16 bit/44.1 kHz standard is already good enough (with or without dithering)?
            I’m a great believer in listening and testing rather than theorising, but most people in the audiophile community prefer the opposite (and Ethan Winer would concur with my statement).

            I like this comment from the following article http://www.head-fi.org/t/571259/hi-rez-another-myth-exploded:
            “The difficulty facing the audio industry is that 16/44 is an old and well established technology. It’s difficult and not very profitable to keep selling the same thing for years. On the other hand, it’s easy to convince consumers that bigger numbers are better, so hi-rez [192 kHz sample rates] provides an ideal opportunity to sell the same customers new equipment and new music collections. Everyone wins, the companies stay in business and the consumers think they are getting something better. The real shame is that instead of spending their development money improving the quality of their products at 16/44, they are spending their money aiming for bigger and bigger meaningless numbers to make their marketing departments happy, while actually reducing audio fidelity.”

          • August 25, 2015 at 10:56 am
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            This is absolutely right on. I would only mention that there are recordings that do better than CDs…and I do believe that it is worth working in specs higher than CDs. It’s up to the artists, engineers, and producers to deliver better sound records. And the labels to release them.

          • August 25, 2015 at 11:06 pm
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            I read that when inventing the CD, and also many years later, scientists found out that the optimal sample rate all things considered was around 50-60 kHz, but the inventers were pressured into settling for 44.1 kHz. As far as I understand, the biggest problem with this is the filtering that takes place at the highest registers. So yeah, I think we can all agree that there is at least some (perhaps mostly theoretical) advantages to higher sample rates. Yet, good recording, mixing and mastering trumps all advantages of higher sample rates (or bit depth) – that’s also what that Boston Audio Society experiment with SACD and CD ended up showing :-).

          • August 26, 2015 at 7:43 am
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            Don’t get me started on the Meyer and Moran “research”. It was a complete failure.

          • August 26, 2015 at 9:24 pm
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            While not defending the M&M research project, wouldn’t it be nice if all the passionate criticism was matched by passionate action, with a follow-up research project, done right? Very, very strange that this didn’t happen. Or is it?

          • August 27, 2015 at 9:28 am
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            There are a bunch of people from students, professors, and professionals working on these things. There have been at least 3-4 new research projects studying this area. I wish I was one of them.

    • February 18, 2015 at 2:35 pm
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      You want to hear true dynamic range and top shelf analog reproduction get your self a Edison wax cylinder player. Not only do they sound awesome but they are truly green in that they’re powered by a wind up motor and use no electricity or fossil fuels what so ever.

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      • July 18, 2015 at 5:10 pm
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        Ha ha ha :-D!

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  • August 7, 2016 at 6:07 pm
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    I listen though an Asus Xonar Essence ST, small (but excellent) T-amp and decent small monitors, at near and medium field in a small-ish room. Foobar/ASIO or Kodi/WASAPI.

    The improved smoothness with hi-res on instruments like violin and small, muted brass is anything but subtle. Or with the sibilants on voices. Or …….

    I hardly ever wince like I often do with 16/44.1.

    This has nothing to do with ultrasonic bandwidth and everything to do with time-domain coherent filtering that preserves timbre within the audio band, and anyone can hear it, even if their aural faculties don’t work much above 8-10 KHz.

    Unfortunately, the same luddites/zealots who used to assure us that lossy-encoded files were indistinghishable from 16/44.1 PCM (this, 10 or more years ago, when digital bandwidth and storage were actually relevent considerations) have moved on to claiming that hi-res is also indistinghishable from 16/44.1 PCM.

    These tin-eared mediocrities infuriate me – THEY are the ones putting obstacles in the path of progress, not “audiophiles”, as they sneeringly call them.

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