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.

13 thoughts on “Time Out

  • November 30, 2014 at 1:34 pm
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    The one saving grace of Blu-Ray audio is that some releases imclude 5.1 mixes of some really great recordings–not all, but some. As far as I know, that is the only way to get those mixes. Not available as downloads.

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    • November 30, 2014 at 4:20 pm
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      Good point, I love surround music…but really how many of them have 5.1 surround mixes?

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      • November 30, 2014 at 10:28 pm
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        Certainly all the SACD and DVD-Audio titles I’ve purchased are 5.1 apart from two SACD when I didn’t realize SACD came with stereo only releases.

        Of course not all are from digital recordings but still sound fine to me.

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    • November 30, 2014 at 8:23 pm
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      My two cents worth… I used to build very high quality speakers and I currently use CLASS A amps with my speakers. I have always been a Vinyl records in the past as my favorite source for the best rock recordings. I was a big fan of the Mobile Fidelity releases and the virgin vinyl Japan releases. My music is more ART ROCK / Progressive Rock. My favorite bands are YES, Supertramp, Genesis, Peter Gabriel, and King Crimson. Recently Steven Wilson has released many of the albums of YES and King Crimson using the BluRay format. They contain the original Mix (Eddie Offord for YES for instance), a stereo high resolution mix and a 5.1 mix (Some are really 4.1 because the center channel is not always used). These recordings reveal details that I never heard in the original recordings. This does not mean that a simple CD struck from these new mixes would not sound the same. I cannot say this for sure. But I can say that these are astounding and like hearing this material as new again! I love each one. So for me, I am buying these BluRay disks when they are from musicians which I enjoy. I agree that the dynamic range is limited but these bands did use dynamics as part of their “painting” of sound. So I will continue to search out and buy the BluRay versions of these for the highest possible quality sound from these original releases, and for the re-imagination of the surround sound versions as a wonderful bonus. I do agree that these new high resolution releases have the “potential” to be much more when not bound by the TAPE originals. But I can also tell you that with a top cartridge and turntable, good amps and speakers, these recordings where far better (Mobile Fidelity and Japan) then the commercial releases of the day. Today is new…. I am embracing the new format.
      Mark

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      • December 1, 2014 at 8:17 am
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        I’m with you on these new versions…and I enjoy these bands as well.

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  • November 30, 2014 at 1:34 pm
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    Given you are discussing vinyl here this is an opportune time to ask a question about some comments that were in circulation at the time CD’s first came out. Some experts noted that early CD’s sounded terrible because in a rush to get CD’s out some manufacturers went to the analogue master that was used to cut the vinyl stamping master. Of course this master tape recording would have (might have) had RIAA equalisation applied to it meaning the resultant CD, not having the compensating RIAA filter in the playback chain as would a phono amp, would sound strange. This could be apocryphal – I don’t now.

    I have only one CD that came out at about that time for which I know have the SACD. That is Roxy Music, Avalon, The CD sound fine but for some reason the SACD sounds much better. Given they ostensibly come from the same original analogue master, that is interesting.

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    • November 30, 2014 at 4:23 pm
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      Early CDs didn’t show off the full potential of the format for a variety of reasons. The use of pre-emphasis, poor transfers from the wrong masters, bad analog to digital converters and digital to analog converters, and the growing pains of a new format. The RIAA curve stuff is true and it’s still happening today as tapes are readied for HD download sites. We’ve gotten better at all things digital…to the point that it makes no sense to embrace vinyl LPs or analog tape unless there’s repertoire that’s unavailable anywhere else.

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  • November 30, 2014 at 5:07 pm
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    As long as we’re talking misinformation here, time to correct a few errors.

    A great many analog recordings were made with noise reduction systems, notably Dolby A Type, and later in the 1980s, Dolby SR. These were double-ended systems where the signal recorded on tape was encoded, and decided during play. They were exactly complimentary systems, and because of Dolbys methods the encode/decode processes tracked each other extremely well without audible artifact (unlike the lower cost dbx system). Dolby A extended the dynamic range of tape an additional 10 or more db, SR did it to 20dB.

    Even non-Dolby analog tape did 72dB from a somewhat arbitrary high level resulting in tolerable distortion to the noise floor. Simple copies add 6dB of noise, but the mix down from multitrack wasn’t ever a simple copy as track levels we obviously adjusted during the mix. The resulting master didn’t necessarily suffer from the 6db noise buildup. Put either of the Dolby NR systems around it, and noise build became negligible.

    Either way it’s not correct to say master tapes had 30 – 40dB dyanamic range. That would be unlistenable and a commercial disaster.

    The RIAA recording characteristic used on vinyl was never rececorded on a tape. It couldn’t be, the curve has a 40dB range to it bottom to top end, and tape saturated easily at high frequencies. The RIAA curve is applied just prior to the cutter amps. Always. Early CDs never included the RIAA curve, that would have made them devoid of bass and unlistenable.

    Some CDs were mastered from what’s known as an “equalized master”, a tape that included final level and minor EQ adjustments intended to make the resulting vinyl somehow better or more consistent. Many of these would make for lousy CDs though.

    CD preemphasis is a fixed high frequency boost shelf applied to the cd master, but every CD has the inverse cut shelf curve built in, and the subcode preemphasis bit switches it in when required. The two are exactly complimentary, the result is flat response with less peak capacity at the high end. It wasn’t used much, but nobody ever heard the non-deemphasized version.

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    • December 1, 2014 at 8:16 am
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      I haven’t addressed Dolby A or SR and DBX encoding/decoding with regards to analog tape. You’re right that they increased the signal to noise ratio but at a pretty substantial cost to accuracy…the alignment procedures and complexity were daunting. It was never seamless.

      Without noise reduction, a very good 1/4″ 2-channel tape could maybe get to 72 (equivalent to 12 bits in PCM land)…but that’s under ideal conditions. 24-track machines, the multitrack standard of the time, didn’t get to 72 dB without noise reduction and the mixdowns to 2-track suffered the generation loss associated with analog copies. Mastering engineers (I was one of them for 13 years) forced that dynamic range down even further. You say that a dynamic range of 30-40 dB would be unlistenable…but those numbers would be considered good these days. Dynamic ranges of commercial releases now are less than that…a lot less. And yet they are commercially successful.

      Masters used for cassette tapes have severe EQs applied to the master AND some of those EQ’d masters have been used for high-resolution transfers according to the head of a major mastering facility. Early CDs used pre-emphasis and other adjustments.

      I stand by the information I presented.

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      • December 1, 2014 at 8:20 am
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        Thanks Stephen…I missed going to the mile high city this year.

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  • December 1, 2014 at 3:47 am
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    Hello Mark, Miss you not being at the Rocky Mountain Audiofest after seeing you two years straight. I’ve been reading some of your news letters and want to Thank You for letting us know what’s the Real deal(Truth) Is going on. Sometimes when we buy music and audio electronic equipment, we want to believe(other Marketing Corp., Advertiser& other Reviewer are saying) that it sounds good and its time when our brain plays tricks or lead us to believe it sounds OK. A Person like you comes along to Wake us up to see the Light(Real Truth) on whats going on. I have Experienced in my religious and Spiritual life thinking and Believing its one way and finding out its another whole kind of truth out there. I’m learning, remembering and being more Objective on keeping an curious, questionable and open mind. Again Thank You for Sharing your Talent and Expert Advise! Keep up the Great Work! Peace, Love and Oneness! Audio Lover- Stephen(Colorado Audio Society)

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    • December 1, 2014 at 1:39 pm
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      Ronaldo…I’ve read the piece and their previous articles regarding the FLAC vs. WAV file stuff. I’ll pull together an article asap. I would like to run the comparisons myself on some of my content. I can say that I’m somewhat dubious about their findings.

      Reply

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