Dr. AIX's POSTS — 23 March 2014

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I’m hoping that yesterday’s post about what is definitely NOT high-resolution audio has sunk in. Some readers felt the need to push back and would like analog tape to be considered high-resolution. But as I tried to explain in my responses to the comments, just because something is preferred doesn’t magically change its specifications or capabilities. I’m fine with analog tape as a format…but it does belong in the standard resolution category. Admittedly, this is going to be the toughest challenge among professional engineers and producers. I fully expect that they will stick to their beliefs that analog tape best represents music when recorded. Again, it’s simply a flavor thing…but not high-resolution.

Today, I’m continuing with the quest for a suitable definition for high-resolution audio. We know what it is not. Now let me share some examples of what is definitely high-resolution!

There’s also the issue of intentions and goals. Clearly, not every artist, engineer and producer are trying to create and release high-resolution music. But I believe it would be preferable to adopt higher sampling rates and longer word lengths during the production process so that there is at least the possibility that the project could include an “audiophile” version. A few artists have done this and I know many original digital productions are done at 88.2/96 and 24-bits. Very few are done at 192 kHz and virtually none are recorded at 384 kHz (there is absolutely no need to go this far…other than impressing people with big numbers).

So here’s my list of recording formats that are definitely high-resolution. [NOTE: These are RECORDING formats NOT delivery formats! A project must have been captured at the time of the original session using high-res equipment for it to be considered high-resolution. Transfers of older non-high-resolution materials will remain standard resolution despite the best efforts of many others in the business.]:

1. 88.2/96 kHz/24-bit PCM – This level of digital recording should be adopted as the minimum standard for true high-resolution recording. The dynamic range of 24-bits (within a production environment that uses many more bits during processing) is more than enough to capture the entire range of amplitudes human hearing is likely to be submitted to (130-140 dB) AND it guarantees that our traditional hearing range is captured as well as the potential (and debatable) next octave.

2. 176.4/192 kHz/24-bit PCM – Despite the protestations of other experts, moving to these sample rates does make sense for audio archiving. I plan to capture analog masters at 192 kHz if provided analog two-channel stereo tapes from the major labels because it means that the PCM digital masters I create will have plenty of specification “margin” to get everything that came from the tape. I personally believe this is overkill but for archiving a classical analog master…no problem. In reality, 96 kHz/24-bits is enough.

3. 352.8/384 kHz/24/32-bits PCM – Some are calling this “ultra high-resolution audio”. I call it marketing nonsense. There is no reason to run capture systems at this rate. We don’t have microphones and speakers that extend beyond 40-50 kHz so why would anyone push the sampling rate past 96 or 192 kHz? It makes no sense.

4. 2.8 |5.6| 11.2 MHz DSD – As all of you know, I have major reservations about this “so-called” 1-bit encoding scheme especially when it comes to producing products natively. But it’s in the marketplace and if used to capture music during an original session, then it meets my specifications (especially if you get away from 2.8 MHz). The problem here is there are no tools to work natively with DSD at any sample rate thus requiring conversion to other formats.

5. 352.8 MHz 24/32-bit DXD – My friend Morten Lynberg at 2L uses DXD at this rate to capture his projects. He posted a notice about an upcoming session at the Berlin AES convention where he and others will discuss the merits of DXD/DSD vs. PCM. What isn’t as widely known as it should be is that DXD is really PCM by another name. Refer to No. 3 in this list…because DXD is actually ultra high-resolution PCM. SONY and Phillips like this format and 2L and others use it because it can be converted easily to all other flavors of PCM and DSD. And because it sounds like it’s similar to DSD, which it is not.

So there you have it. Another set of five formats that ARE DEFINITELY “high-resolution audio” if used during an original session. We know what HRA isn’t and we know it is…now, think about the downloads you can purchase from the usual suspects. Are they high-resolution or not?

There’s a definition in there somewhere.

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About Author

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) Readers Comments

  1. Mark,
    I’ve been following your blog for quite some time now, and I have to say that today’s installment did somewhat surprise me.

    Specifically number 4 in that list: you’ve been writing about the ultrasonic noise which comes inevitably with the 1-bit encoding scheme when the data is decoded again (I hope I got that right) and the necessity to employ a low-pass filter which cuts off everything beyond 20 kHz.

    But doesn’t that mean that effectively, DSD can’t be better than PCM with around 40 kHz sampling rate? Let’s take 44.1kHz/24bit for example, which – according to your classification – is not High-Resolution. Wouldn’t this be just as good as DSD 2.8MHz?

    Best regards,
    Oliver

    • You’re absolutely right and I did hesitate to include DSD 64, the one set at 2.8224 MHz, for just that reason. It does a great job covering the normal “audio band” but goes no further. It might them be reasonably excluded…but in the interest of being polite to the DSD world, I included it.

  2. Mark,
    I agree that tape does not have the dynamic range of digital, not even close, except many years ago I was half kidding half wishing while speaking with John French at an AES show, and I said “Why not make a 2″ eight track head stack?”

    Two years into the future, NY. AES once again, I bumped into John who pulled me aside to show me something.

    A producer had indeed contracted him to build the fantasy 2″ eight track head stack.

    He also now makes a 1″ two track headstack, and with these running at 15 IPS for the massive bottom end headbump, the dynamic range is 20 dB up from that of a standard system.

    With properly aligned EQ cards, the machines are fully capable of beyond 20Hz 20KHz bandwidth.

    The transports of a well aligned 2″ or 1/2″ Studer, or even the humble Otari are well capable of outperforming the totally gorgeous Nagra 4s, for which I have a very soft spot in my heart, and have made many a live recording with, including a “Live At The Village Vanguard”, which sounded beautiful, but as we both agree, is not exactly hi res.

    Many of us love using analog precisely for it’s limitations and lovely tape saturation, which just does not sound the same from a plugin.

    The bandwidth of a freshly recorded 2″ 24 or even better, the 2″ 16 for it’s lower noise floor and juicier fatter sound, (since we are limiting dynamic range by smashing the tape, that part doesn’t quite matter), is certainly capable of 20Hz- 20KHz, and is then dumped to Pro Tools before the tape looses the sparkle, which does happen overnight.

    This is a beautiful way to get great rock guitars, huge grinding bass, and big powerful punchy drums, and then bump to dig and finish off all the things that really benefit from the superb dynamic range and gorgeous black.

    Bruce Swedien was and I believe still uses this trick with appropriate projects.

    Any thoughts on the CLASP System, and mixed format recording as mentioned above?

    I heard Eddie Kramer remark during a documentary I saw yesterday, “It is funny how all these digital guys are using tube mics, tube pres, tube, EQs, tube compressors, 50 year old technology to warm up the digital”.

    Although I will admit, I wish I bought up a lot more tube equipment when the solid state craze was hot in the 80s, because the good stuff is not inexpensive any more.

    Just try to buy an original Pultec for $400 today, lol!

    Thank you for another important subject.

    • This is a very interesting comment! Thanks for taking the time to put your thoughts down in words. I couldn’t agree more. Tape is a wonderful medium and in the right hands is part of an engineer’s tool set that can define a particular sound. Wouldn’t change a thing.

      And I’m encouraged to hear you say that it is actually not capable of reaching the same specs as HD-PCM (unless you have a tricked out custom headstack) and is therefor technically standard resolution…but it doesn’t matter! The sound is king! So why would anyone…including engineers and producers…dispute that the raw fidelity that is possible using HD-PCM is another flavor.

      Cheers….loved it. Have fun.

  3. The concern I have with this discussion of high-resolution audio is that it is entirely one dimensional. Should the determination of high-resolution be focused solely on the quality of one track? Is a 96/24 1.0 (mono) recording high-resolution audio? To me a well done 48/24 5.x recording is higher resolution than a well done 96/24 2.0 recording of the same performance. There is more information in the 48/24 5.x recording than in the 96/24 2.0 recording.

    • The number of channels, miking in stereo or processing for headphones is another topic and not actually a factor in pure fidelity. Having more channels doesn’t contribute to “resolution” but to the experience of spatial distribution. I prefer surround and would be hard pressed to say I prefer a 96 kHz/24-bit stereo track to a 48 kHz16-bit 5.1 mix.

  4. I think including DSD 64 on Marks list was the correct thing to because it is out there. Someone needs to decide what High resolution audio is and isn’t and Mark has done that. Once this is accepted, then the folks that push their analog copies as HRA will hopefully fade away.
    I’m all for having the chance to obtain a better copy of say, Supertramp, Breakfast in America than my old LP or CD. I did indeed purchase the “High Fidelity Pure Audio Blu-ray disk (no video content) and it does sound better than my old LP.
    But it is, what it is. I don’t have a spectrograph to look at the audio content, so I will not call it HRA. But I think Mark is doing the audiophile community a favor by defining what HRA is, or isn’t.

    • I love the line “once this is accepted”…as if that’s actually going to happen. All it’s going to take is for the CEA and download sites to be honest and transparent about what they’re doing. And for Neil Young and Pono to stop spinning and start explaining.

  5. Mark, your the one who turned me on to 2L. I bought there Blu-Ray disc “2L the Nordic sound” and was blown away by sound on my run of the mill 7.1 system. Not taking anything away from your work but it is the best thing I’ve ever heard.

    • I regard 2L’s work as among the best on the planet…I’m glad you enjoy their recordings. I just hope you’ll keep listening to AIX stuff…you might just find something that best them!

  6. Why do you confuse the issue with number two when you say you use this to capture analogue masters? As you stated before analogue masters cannot be considered high resolution. I think including this statement here is out of place because it may lead someone to again think analogue masters are high resolution.

    • I should have been more clear with my statements in No. 2 of my list. If I’m able to get two track masters (flat masters!) from the labels, I would transfer them to digital at 192 kHz. I will not call them HD or high-resolution audio because of the source but I would move to 192 to give me plenty of margin.

  7. Hi Mark,

    As a relative newcomer to the audiophile world and the search for “real” HRA recordings, I really appreciated your weekend blog posts about What HRA is Not and What HRA is. This certainly helps to distinguish which audio tracks one might look for in building up an HRA library.

    However, even after all that, I think that I still have trouble differentiating between real HRA tracks recorded in HRA at the recording session and tracks claiming to be HRA but actually are only say 96/24 buckets containing 44.1/16 recordings.

    Here’s a simple example – on Acoustic Sounds, they announce that they have HD tracks of the Creedence Clearwater Revival from analogue recordings. HD Tape Transfers follows the same pattern – analogue tape recordings that are passed through some fancy gadgets and produce HRA tracks. It’s easy to see that these tracks are not “real” HRA.

    But then I go to HDTRacks which advertise Paul Simon’s Graceland as an audiophile recording at 96/24. How am I, the humble customer, supposed to be able to determine whether that was a record session recording or simply a 44/16 put into a 96/24 bucket? Must I learn the intricate language of a recording engineer to figure out whether I have purchase a real HRA recording or a non-HRA recording put into an HRA package?

    Thanks for making sense of a complicated subject – I have learnt a huge amount in the past few months for which I am truly grateful.

    Charlie

    • I can certainly appreciate the frustration and confusion regarding the whole high-resolution business. The simple way to think about it is that anything that’s older than about 1995-2000 is most likely an analog recording…meaning it was recorded on a 24-track 2″ machine. So every track that Acoustic Sounds or HDtracks sells from this period or earlier is not a high-resolution track.

      I plan to have a comprehensive database of this information within the next several months. Stand by.

      • Mark,
        This database would be a fantastic resource for us all.

        The Sony DASH format came out in 1982 with the 3324 IIRC, I remember those machines, they weighed a ton.

        They did 48/16 and then Mitsubishi came out with their X-80 maybe the following year, do you recall?

        Donald Fagen’s nightfly was done on the Sony, and there is a Spyro Gyra album we had in the house that was on the Sony 48 track back in 92.

        We were all mixing to DAT and 1/2″ at 15 or 30, and 1/4″ at 30 running +6 or +9 on the 1/2″ machines and +6 on the 1/4″, so there should be DATs or some form of dig along with any of the analog masters of all of these recordings, somewhere.

        The question is, where!

        What I am concerned with, is the powers that be fearing that getting these gorgeous masters reproduced in HRA will show just how much of a scam MP3 has been.

        Folks have been paying the prices for CD digital audio (surf and turf) and getting PB&J sandwiches on stale bread, and absolutely loving it.

        What kind of outcry might there be if the cat were let out of the bag?

        Sincerely,

        John Chase

        • I’ve used 3324 and 3348 machines. What originally costs hundreds of thousands of dollars are now virtually free. My how technology moves on…especially digital technology. I remember the 3M and Mitsubishi machines. I think most mixing was still done to analog tape…even the fancy formats like 1/2″ 30 ips with Dolby SR.

          The DB will try to get all of this information on the record. We’ll see how it goes over.

          • Yes, most guys I know were mixing to analog and runnigna DAT as backup.

            Some folks are still mixing to analog, but with some crazy souped up machines with beautiful custom eletronics and 1/2″ or even 1″ two track and running the 1″ machines at 15 IPS for the phatness, lol.

            It does sound quite beautiful!

          • You’re right…but how do you distribute it?

          • My hopes are that these masters will be made into digital files (as they are now) through any one of several fantastic DACs available at a sample rate no less than 96k@ 24 or even 32 floating word length, and distributed as self extracting PCMs or some form of lossless format for D/L.

            However, it would also be fantastic to have made available a hard copy format like the Blu-Ray disc, or a DVD which is what we have saved Pro Tools sessions on for quite some time now.

            Although IIRC, the archivability of the B-Ray is superior to DVD, yes?

            Many people I know like the tactile feel of a hard copy and the enjoyment of the process of selecting a disc or vinyl, and placing it in/on a device to play the music.

            Sort of like sitting down to a great meal, smelling delicious aromas, or popping a pill containing a five course tasting menu.

            Which would you prefer?

          • I’ve produced over 85 discs and the challenge now is to decide whether to re-replicate a product that runs lows. It’s expensive to maintain inventory and physically sell discs. Files are much smarter. It will be a long time until I run out of Blu-rays but some of the older DVD-A/V discs are going to file based delivery only.

  8. An article at Crutchfield.com called ” Intro to high res audio” seems to generally agree with your views on this subject.
    All else being equal, 24/88.2+ sample rates should sound better than CD quality, but as you have mentioned, all else is usually not equal. High res audio is not synonymous with better sounding audio for consumers.

    • I spoke with the author of the Crutchfield piece…it’s not bad. I suggested some changes but they had already gone to print.

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