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.

7 thoughts on “Promates and High-Rate PCM (DXD) Downloads

  • Nik Razis

    Thanks for this. Your findings come as no surprise. There do seem to be differences on the lower (up to about 35k) part of the spectrum. Would you know why this is? Doesn’t look to me to be just the result of the 5dB difference, but then I haven’t looked at a spectrogram since the 80s.

  • Joe Whip

    I was wondering Mark, whether you heard a difference between the files once you level matched? Thanks for your efforts.

    • Admin

      The 88.2 kHz/24-bit file had every bit as much “nuance” and “low level detail” as the DXD file…for half the money and a third the file size. The Promates people got the last chunk of money from me.

  • Grant

    Excellent article. Thank you.

    When we buy one piece of music for a price that we could have bought two pieces of music for, and get nothing audible in return, then the main effect of ultra-high bitrate music sales is to reduce the size of our music collections at home.

  • Thank you for setting the record straight!
    I used to think we needed the highest resolution possible but you made it quite clear through detailed graphs (thanks for explaining how to interpret them) what is really necessary and nothing more.

    I now realize 96 kHz/24-bit provides all the necessary quality as well as being essentially future-proofed in regards to higher quality playback devices.

    We can now have our cake and eat it too as they say (download high quality and save a few bucks)
    Great posts and VERY informative.

  • Melchior-Christoph von Brincken

    The point of having 352khz resolution is not to have more detail, but to have the DAC less guessing and making errors while doing so. So it is about precision in the time domain. If the “guessing errors” at 44.1khz equal 100% error, with 96khz it is only 1/2 and with 192khz 1/4. With 384khz only 1/8 of the errors would be left.

    352khz = YOU GET LESS DIGITAL NOISE = more natural and relaxing sound.

    I recommend to put the audio tools aside and start listening.

    • Admin

      I beg to differ. Since when to DACs guess at the amplitude values at each sample point? They don’t. There is quantization error according to the Shannon-Nyquist Theorem but that’s not the same as guess in a DAC. Increasing the sample rate beyond that needed to correctly sample the required frequency spectrum and provide the electronics with simple filtering doesn’t result in a “more natural and relaxing sound”. Your description of the process doesn’t mesh with the facts in audio encoding. I would challenge anyone to be able to perceive a difference in fidelity between the same file at 384 kHz and 48 kHz…no one can. I do lots of listening, have been a professional audio engineer for decades and instructor of audio for almost as long. Tools are exceedingly value in assessing the potential of an audio system…we should be using our ear to validate advances in technology. Moving beyond 96 kHz has absolutely no audible sonic benefits. It does however allow manufacturers to increase their profits.


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