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.

9 thoughts on “Intro To Recording: Day 1

  • August 28, 2014 at 2:51 pm
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    Very basic physics, do you think we ( your readers) are unaware of this?

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    • August 28, 2014 at 2:59 pm
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      Yep, I do think there’s a lot of readers at all levels visiting this site.

      Reply
  • August 28, 2014 at 7:01 pm
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    Light and radio signals are electromagnetic waves, which is a completely different phenomenon from acoustic waves. You do not progress from one to the other by changing frequencies.

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    • August 29, 2014 at 8:47 am
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      The graphic and discussion doesn’t speak about acoustic waves…it focuses on signals and their frequency.

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      • August 29, 2014 at 6:55 pm
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        While your intention to focus on signal frequency is clear, the inclusion of wavelength in the graphic is incorrect for audio/sound signals. The wavelengths are for electromagnetic radiation not sound.

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        • August 30, 2014 at 9:07 am
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          Are you claiming that audio signals don’t have any wavelength? Humans can hear…20 Hz to 20 KHz. The speed of sound is around 340 meters per second. So the range of audio wavelengths is 1.7 millimeters to 17 meters.

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          • August 30, 2014 at 10:16 am
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            The problem with the graphic is that it specifies a wavelength of 30 km to 300 km for the audio signal wavelengths. That’s an error of more than 7 orders of magnitude. 30 km to 300 km is correct for propagation of an electromagnetic wave in a vacuum; it’s not correct for sound wave propagation at standard temperature and pressure.

          • August 30, 2014 at 12:24 pm
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            Thanks for the clarification. I would not have included the wavelengths if they weren’t part of the chart that I based my diagram on.

      • August 31, 2014 at 4:37 am
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        You wrote: If the frequency of a signal is in the range of 20-20 kilohertz (kHz), humans hear this as sound.

        This should have read: If air molecules are vibrating in frequencies from 20 Hz to 20 kHz, humans hear this as sound.

        There are radio waves that occupy this same frequency range (designated SLF, ULF, and VLF). We obviously don’t hear them as sound, because they are oscillations in the electromagnetic field, rather than vibrations in the air.

        You wrote: As the frequency increases beyond our hearing range it manifests itself in other ways…including light and radio signals (see illustration below):

        This should have read: as the frequency of vibration increases, we no longer perceive it as sound. Still, ultrasonic vibrations can exist at least up to a few hundred kilohertz in air.

        Defining an absolute limit is difficult, because air is a mixture of different types of molecules. And, anyway, very high frequencies will only propagate over short distances before being absorbed.

        Unless writing about electrical signals, it doesn’t make sense to define DC is a lower bound; it should simply be 0 Hz. (Of course, 0 Hz, itself, is not a frequency, as it has no period and infinite wavelength.) Writing that anything extends beyond infinity is clearly nonsensical.

        Mixing electromagnetic waves and terminology relating to electrical signals into a paragraph that introduces frequency as one of the properties of acoustic signals will only confuse anyone you are trying to educate.

        Reply

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