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.

22 thoughts on “Research That I Can’t Talk About

  • January 13, 2015 at 5:49 pm
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    A bunch of academic institutions including MIT would do science the right way and have more credibility than the industry or other interest groups.

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    • January 14, 2015 at 7:45 am
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      Funny, I’m wearing my new MIT T-Shirt this morning…my son finished grad school there last June. I’m convinced I could pull this off and am going to start the process of acquiring the equipment and expertise.

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      • January 14, 2015 at 9:30 am
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        The funniest thing is that WAV/AIFF/AU are restricted to 4 GB file size & W64 format does not actually work.

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        • January 14, 2015 at 11:56 am
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          I use w64 all the time, works fine for me.

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  • January 13, 2015 at 6:15 pm
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    Indeed, Mark, it is most disappointing to witness just how this whole issue of a “standard” of high resolution audio is being handled, defined and promoted.
    I have a keen interest in high quality audio recording and reproduction. As an older guy, my hearing is less than ideal, but I know and appreciate well-recorded and replayed material when I listen.
    So much of today’s popular music is “over-produced” and compressed to within an inch of its life. It would seem, to me, to be almost impossible to hear much difference between an MP3 and a 24/96 file when played through the average portable device and ear buds.
    As an owner and user of very high quality digital interfaces and microphones, etc., it often makes me smile to scan the articles and ads in audio lifestyle magazines and observe the investments required/recommended to achieve “audio nirvana” in one’s listening room.
    I could rabbit on about recording techniques and production values, etc. at length. But the bottom line is the integrity and provenance of the recording itself. Along with that is the experience, expectations and “training” of the listener. In an attempt to convey a realistic representation of the musical event, consideration must be given to exactly how much of the available sound information is retained… the more subtle cues, for example, of space and sound transients which have captured by the engineer.
    I agree with you: DSD is not the answer. High accuracy PCM at 24/96 minimum is required to capture sufficient detail to convey any sense of “being there”.
    Keep up the good work: don’t be discouraged by sloppy and money-oriented practices. Education of music lovers is the thing. There will always be a group of people who desire and aim for excellence in music reproduction and performance. Mediocrity sucks.

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    • January 14, 2015 at 9:52 am
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      A.S. I solely proposed a digital audio format which is far higher quality sound than had been touting for on this site.

      1} 16-bit recordings with perforce limited 120 dB pressure peaks are perfectly reconstructed with noise shaping & there is no need in either 24-bit and 120 dB SNR equipment

      2} The reason why CD does not feature subtleties is in anti-alias filter. This is mostly why 192 kHz sounds perceivably better. Upsampling can partly solve the whole problem.

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  • January 13, 2015 at 8:41 pm
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    Who says lossy MP3s are not ‘standard resolution audio’? Has the term been defined and agreed upon? lol

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    • January 14, 2015 at 7:49 am
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      I do. CDs, vinyl LPs, and analog tape are very good but still standard resolution…which we’ve been producing for many decades. Lossy, compressed files are below that. I refer to them as “reduced resolution”. And High-Resolution is anything above 96 kHz/24-bits as the JAS has it.

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      • January 14, 2015 at 8:35 pm
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        I was meaning to point out the futility and frustration of dealing with scientifically undefined terms…

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  • January 14, 2015 at 5:52 am
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    Hmm, hate to say it but it almost sounds like the researchers provided study results that they thought the people that hired them wanted to hear. Maybe the researcher weren’t ignorant, rather they had that specific goal in mind and to achieve the goal they had to ignore some facts.

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    • January 14, 2015 at 7:56 am
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      There are lots of other problems in the reports that point to a lack of knowledge. They said the samples were played at 17 dB and 22 dB…if that was the actual sound pressure level, nobody would have heard anything.

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  • January 14, 2015 at 10:16 am
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    Glad it is the school and not the cable manufacturer although the cost of some of their wire is probably as high as the tuition! Congrats to you and your son, it is quite an achievement.

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    • January 14, 2015 at 12:42 pm
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      Yes, very proud parents…he’s a smart one. Snagged one of 5 Fulbights this years out of 1000 applicants too. He in Mexico City doing his project. Thanks Joe.

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  • January 14, 2015 at 10:19 am
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    Having given thousands of demonstrations that evinced the listener’s aural acuity, I have come to only one firm conclusion; virtually anyone if guided properly will hear the difference between a source containing significant amounts of transient intermodulation distortion products and one which has vanishingly low levels of same. As you say Mark, that’s simply comparing awful sound to excellent; that’s not the comparison of concern.

    As for the audible difference between 16/44 done well and 24/96 similarly well executed, I would cheerfully predict that trained listeners would have little problem , but the control would have to be a good recording of carefully chosen music, identical playback output stages and no stress on the listeners due to test circumstances.
    For a wider perspective, I personally think most folks would hear a difference between 16/44 and 24/96 but would need some ear/listening training first. Folks such as you and I who have used our ears critically for thousands of hours do in fact have greater awareness and wider angle perception than folks who have never gotten involved w/ hi-fi listening. A neurophysiologist who recently visited my shop made that statement to me in no uncertain terms. This all at least partially explains some of the bizarre results that so-called ‘controlled tests’ often generate; too many variables in this equation, results all over the place.Hearing is believing, simply put.

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    • January 14, 2015 at 12:44 pm
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      It’s important to do the rigorous test…I’m not yet convinced.

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      • January 18, 2015 at 2:12 am
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        Here is some food for thought and/or further experiment: http://www.davidgriesinger.com/intermod.ppt
        It’s a few years old, but the analysis is driven by physics and physiology, which I don’t think will have changed in the mean time.

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        • January 18, 2015 at 12:09 pm
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          It’s a long Power Point presentation. I’ll read through…but I know the paper they depend on.

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    • January 14, 2015 at 4:38 pm
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      Craig,
      Regarding the effect of stress on aural acuity, stress may actually improve the listener’s ability. We evolved to be able to accurately analyse audible cues while stressed. You’re wandering through the forest, thinking of lunch, when you hear a twig snap. Is it someone else thinking of lunch, or is it someone thinking of having you for lunch? Successfully analysing subtle audible clues will make the difference between eating and being eaten.

      I do accept that stress from external sources should be minimised (comfortable chair etc). The listener should be able to give their full attention to the task rather than being distracted.

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  • January 14, 2015 at 5:34 pm
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    Hey Mark,

    This research into the audibility of high resolution audio reminds me of the Pepsi Challenge. As detailed in Malcolm Gladwell’s book “Blink”, Pepsi’s blind sip tests in the early ‘80s convinced Coca-Cola to bring out a new formula of Coke that bombed in the marketplace. Why? The blind sip test favored Pepsi’s sweeter formula, but the experience of drinking the whole bottle (or can) ended up favoring Coke’s original formula.

    Is a double-blind listening comparison the audio equivalent of a cola sip test? Maybe it takes an extended, relaxed listening experience (drinking the whole bottle) to appreciate the qualitative difference of high resolution audio recordings. I know that’s been my experience.

    Allen Farmelo has some interesting thoughts on this in his article “The Possibility Of Subconscious Auditory Effects In Audioworkers”. http://www.tapeop.com/blog/2015/01/14/subconscious-auditory-effects/

    Food for thought.

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    • January 15, 2015 at 8:28 am
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      Thanks Russ…I agree there’s a lot more to evaluating this than what’s been attempted.

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    • January 19, 2015 at 9:55 am
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      Another parallel to draw from the Pepsi challenge- I had a friend that worked for one of the soda manufacturing giants. People would get on film of the challenge and disappear so Pepsi couldn’t get a signed release thereby hijacking the events. It reminds me of Marks constant battle of companies and people hijacking definitive standards for HRA.

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      • January 19, 2015 at 12:18 pm
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        You really can’t trust anything that promoted or marketed. Not surprised.

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