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 “Sounds Authoritative…But Wrong!

  • August 10, 2014 at 2:48 pm
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    Thanks for keeping the honesty flame burning.

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    • August 10, 2014 at 3:45 pm
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      It just drives me crazy…how is a person supposed to know? You read these things from seemingly reliable and smart people and it turns out that they shouldn’t be writing the stuff.

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  • August 10, 2014 at 2:58 pm
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    Thanks for all the newsletters.

    I do not have the time to delve into the technicalities and debates about sound but I do struggle to find HD recordings that I like. Up to now I have mostly been dependent on importing SACD’s disk.

    Please add -some audio clips to your HD ads. I do not want to buy material I cannot per-audition.

    Thx

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    • August 10, 2014 at 3:45 pm
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      There should be audio samples on iTrax.com for all of the tracks I offer.

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  • August 10, 2014 at 5:31 pm
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    “…the 24-bit flavor can handle higher input and output levels not more resolution within the amplitude range.” I’ve read a number of statements like this in your blog,, and they are wrong, or at least represent a limited viewpoint. Consider a sound source with a maximum amplitude of 120 dB SPL — it doesn’t matter whether it’s an orchestra, rock band, or anything else. You can capture that sound source with either a 16-bit or 24-bit system. The 16-bit system cannot resolve anything below -93 dB, or 27 dB SPL in this example. The 24-bit system may capture the goings-on approaching 0 dB SPL — limited by the noise of the microphones, microphone preamplifiers, and analog to digital converters. At those low levels, the ventilation system in the hall will be competing with the sounds produced by the instruments, but that’s still information not resolved by the 16-bit system.

    Looking at it another way, an analog to digital converter might accept a maximum signal of +24 dBu. If the ADC is set to 24-bit operation, it will record smaller fluctuations in the voltage signal than if it was set to 16-bit. The maximum input level does not change, but 24-bit operation captures more resolution.

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    • August 11, 2014 at 8:57 am
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      Andrea…you and I have discussed this previously. The addition of 24-bits does not increase the number of “loudness levels” as claimed in the quoted piece. 16-bits are able to capture and deliver a theoretical dynamic range of 96 dB, with the noise floor actually 93 dB below the peaks as you state…and that’s a very long way down. Adding 24-bits doesn’t increase the number of “loudness levels” within that same range, which I believe is consistent with your comment. This the problem with writers stating that 24-bits increases the resolution…it does not. It adds additional capability with regards to capturing more dynamics. Perhaps you and I appreciate the term resolution differently. I don’t agree that 24-bits “slices” the available dynamics into more discrete values or that it adds resolution to system.

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      • August 12, 2014 at 10:04 pm
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        Apparently I haven’t explained well enough.

        An alternating voltage representing a music signal comes into an ADC. Presumably you’ve adjusted the microphone preamplifiers etc. so that the maximum SPL generates a voltage swing that is close to the maximum input of the ADC — e.g. an ADC with maximum input of +24 dBu excepts voltages from -12.28 V to 12.28 V. You can record that signal with either 16 or 24 bits. The maximum amplitude is the same. As the voltage fluctuations get closer to zero, they can no longer be captured by the 16-bit system. If using 24 bits, smaller amplitude variations can be recorded. For example, a signal with amplitude 110 dB below that of the loudest signal you set your levels to capture is lost by the 16-bit system, but preserved by the 24-bit system. The ability to discriminate smaller signals in the same amplitude range seems a good working definition for more resolution.

        I can’t comment directly on the article you are quoting, because you haven’t provided the link. I would not use the words “volume levels,” but increasing the system’s bit depth does increase the number of discrete voltage levels that can be recorded in a given range.

        Stating that a 24-bit system can handle higher input and output levels, as you do, is backward to the way in which we use increased bit depth/dynamic range. Whether recording with 24 bits, 16 bits, or analog tape, you set your levels not to clip at the maximum volume from the performance. The tape loses all of the detail 60 or 70 dB below the maximum input, the 16-bit system 93 dB below, and a state-of-the-art 24-bit system better than 120 dB below peak amplitude. It’s the small signals we gain with greater dynamic range in the recording medium. (I acknowledge that having more dynamic range than is needed in the 24-bit system allows for greater safety margins when setting levels, but that does not greatly change the argument.)

        Lastly, the rest of the world does seem to regard bit depth as a measure of audio resolution:
        http://en.wikipedia.org/wiki/Audio_bit_depth

        Alternatively, you can Google “analog to digital converter resolution” to read many articles on this basic concept of digital systems.

        Mark, you’ve got a lot of good information on your website. That’s why I don’t like to see this error persist.

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        • August 13, 2014 at 10:15 am
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          Andrea, I really think we’re saying pretty much the same thing. It’s just the terminology that is getting in the way. The Wiki article and the general concept that 24-bits offers greater resolution than 16-bits is absolutely true…but it’s the details that get in the way. Some writers want to think of the same amplitude range being covered by the additional levels and therefore we get greater resolution…like the additional density of pixels when the dots per inch goes up. I look at it based on the capabilities offered by each additional bit added to the digital words. Yes, we get more discrete values into which we can approximate a sample value (quantization noise) but we also expand the dynamic range by approximately 6 dB. That’s why I insist that a 24-bit system can handle more “input and output” levels than a 16-bit system. 24-bits can deliver a wider dynamic range by virtue of the lower noise floor than 16-bits…theoretically 144 dB vs. 96 dB.

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          • August 15, 2014 at 4:28 am
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            It’s absolutely correct to say that the system with greater bit depth and greater dynamic range can handle a wider difference in amplitude between the largest and smallest signals it can record. It’s also true that the total available range is broken up into more discrete levels.

            A 16-bit system divides up the voltage range — e.g. the -12.28 V to 12.28 V of my previous example — into 65,536 discrete voltage levels. Moving to a 24-bit system adds 255 discrete voltage levels between each available value in the 16-bit system for a total of 16,777,216 discrete levels over the same voltage range.

            A simple analogy is that of moving from a system that rounds values between -10 and 10 to the nearest integer to one that rounds to the nearest 0.1. The increased resolution isn’t only between -1 and 1, but also between 7 and 8, for example.

            I read your comment in this article as disputing that fact, but perhaps that wasn’t your intention.

            When thinking about resolution and dynamic range, it’s important to remember that small signals don’t exist only in isolation. A signal 110 dB below full-scale may be present when nothing else is going on. More likely, it’s overlaid on a far larger signal. In either case whether or not it can be accurately recorded depends both on the number of quantization levels available and on the analog noise floor of the system.

            Although it is correct to state that increasing bit depth increases the number of discrete voltage levels into which the overall voltage range can be divided — as it seems the other writer was pointing out –, and that a greater bit depth allows for greater dynamic range — as you have written many times –, neither statement gives a very complete picture of what is gained by increasing the number of bits. Writing good educational articles is hard, and trying to summarize a topic like this in a sentence or two tends to lead to misinterpretation.

          • August 15, 2014 at 7:14 am
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            Andrea, I reached out to my guru of all things digital and sent him your comments questions. Check out today’s post and this link.

    • August 11, 2014 at 2:03 pm
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      Andrea, Mark is right. You are confusing the terms ‘range’ and ‘resolution’. A dictionary will confirm this. Regards.

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      • August 15, 2014 at 2:42 pm
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        Thanks Mark. It’s a nice article by John. I’ll follow up on your new post.

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        • August 16, 2014 at 6:29 am
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          I want to thank you for the exchange…without it, I would not have reached out to John for his input. I think he’s one of only a few experts that can write and explain this stuff well.

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  • August 10, 2014 at 11:21 pm
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    Top CD players of yesteryear used to pay special attention to digiatl and analogue filtering of player of output. Not so much today.

    192 kHz oversampling often makes previous CD recordings sound better because of getting rid of filter artifacts that can often be heard on modern players.

    However when it comes to recovering missing information, I was remindened of a terrible saying that I once heard:.
    “You can’t make a pig from a pork sausage”

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  • August 11, 2014 at 3:34 am
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    I am glad that you did not write a negative comment on your friend’s blog. I do not believe that some of these HRA explanations are intended to mislead. HRA is difficult to explain in a short and easy way so that general consumers can understand it. Most people would never read the full explanation.

    I do hope that we will begin to see the recently adopted source labels on HRA downloads soon though. For those of us who do understand that it is the source that matters, I would like to save some money buying up-sampled downloads.

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    • August 11, 2014 at 8:58 am
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      Donald, the sales pitch about upconverting MP3s to 192/24-bits is misleading. Either the author doesn’t know the facts or is deliberately writing lies…I’m not content with either choice.

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  • August 11, 2014 at 5:44 am
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    Mark,

    Thanks again for the daily updates. They really do round out my day!

    Facts are not really important to most people. Most folks just want to believe. They have all sorts of constructs built around themselves. Most of them are as flimsy as fairy tales.

    Take a solid piece of cabinetry. You know what good joinery is (judging by your dovetail remarks in the past). You know what constitutes even a simple, but elegant piece. Solid materials. A sound material understanding of how different pieces work and fit together. And most importantly how expansion and contraction over time will affect the work.

    You explain this in intimate detail to all of your friends and acquaintances. You even show and demonstrate the simplicity, durability and beauty of a well-made piece. Don’t waste your money on flimsy nailed/fastener connected junk, you say.

    But the Ikea – or pick your woodpile – retailer continues to grow.

    The Austrian economist Ludwig von Mises understood this apparent cognitive dissonance a long time ago. Everyone has different valuations. Value has nothing to do with price, or quality, or time preferences – short term or long term. Those are only flags or markers. Values are always subjective and are as unique as people are individual.

    But I still appreciate your dogged determination! Keep it up.

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    • August 11, 2014 at 9:00 am
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      Thanks. The woodworking analogy is appropriate and I miss not being able to work physically with wood. There was a real joy in feeling a couple of pieces of wood come together in a dovetail.

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  • August 12, 2014 at 5:11 pm
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    The gentleman with the up-sampling digital hub should be arrested and taken out of the gene pool.

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    • August 12, 2014 at 5:31 pm
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      Yes, he’s definitely been drinking the cool aid. And yet he vigorously defends his hardware. But I guess that’s what salespeople are supposed to do.

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  • August 15, 2014 at 10:04 am
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    Interesting — Author X has been spreading this misinformation since 2012 when he first wrote this “advertisement” for a Sound & Vision and HDTracks collaboration back in 2012.

    This “new” article on HighResAudioCentral is just a regurgitation of that original advertisement.

    It’s unfortunate that this “expert” continues to spew this nonsense.

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    • August 16, 2014 at 6:15 am
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      I was taught that if you don’t know something…do some research and make sure you get it right. The amount of bad information out there is astounding…including the stuff that passes for “standards”. The high resolution audio definition strikes me as a prime example.

      Reply

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