Let me state right up front that I’m crazy about immersive surround mixes when it comes to high definition music…or any music for that matter. I’m not talking about the “extracted” or DSP-processed expansion of stereo to 5.1 channels but the real deal…mixed directly from the source multitrack masters. Mixes that place you smack dab in the center of the musical action. But I acknowledge that music lovers have different tastes and experiences when it comes to listening to music so I’ve tried with my recordings/mixes to offer choices. That’s the reason why there are “Stage” and “Audience” mixes of every track that I’ve produced for the label.  And, of course, stereo mixes for the audiophile that has his/her two-channel system thoroughly dialed in (or can’t expand to a full surround setup for financial reasons or space limitations).

It’s interesting to me that vast majority of HD audio tracks that are downloaded from the iTrax.com site are 2-channel 96 kHz/24-bit versions. Obviously, I’m in the minority when I profess a preference for surround sound. But whenever I demo tracks at a trade show or in my own room, the “stage” mixes are almost always the favorites. I think when it’s done well, multichannel can be very compelling. Why the disconnect?

I know AIX Records was the first to have multiple mixes on their DVD-Audio/Video titles and I believe iTrax.com is the first website to offer the same thing. But why bother…not very many other engineers or labels give you the choice of being on stage with the band or sitting in the best seat in the house.

I’ve been an audio engineer for over 30 years and a musician for a little longer. I remember the age of “quadraphonic” records and dabbled in multichannel presentations of my electro-acoustic compositions while studying at UCLA and Cal Arts. The compositional component of my dissertation was recorded using a Neumann KU-81 “binaural” head. It was first time a composition doctoral student did something that was actually heard by his/her committee members…all listened to the 20-minute piece wearing headphones. I still have my trusty Nagra IV-S portable analog reel to reel machine that I used all those years ago to capture and playback those binaural source tapes.

My goal in creating “stage” perspective surround mixes is not to use technology to transport you to the local rock arena, jazz club or late night rave. I’m not a fan of live recordings. It requires too many sonic compromises…at least for the recording crew (and for the paying audience). After all, the primary purpose of a live performance is to engage or entertain the audience. That means you’ve got to have a PA system to project the sound uniformly to the assembled masses or intimate group of 20 club patrons. The microphones used on stage are usually the venerable Shure Bros. SM-57 dynamic mikes. As good as they are…they’re not generally associated with high end studio recording and are definitely not the mike of choice for most vocal or instrumental tracks. They are used in clubs and on arena stages because they are inexpensive, reliable and virtually indestructible.

My philosophy of recording is to use state-of-the-art recording technology to bring the band to you, the listener. Imagine Willie Nelson or John Gorka and band setting up in your media room to play a private “house concert” for an audience of one…you! The sound can be captured using the very best microphones, preamps, AD converters and high bit rate digital equipment (analog recording…even the best of the best is still standard definition).  If the performances are done in a live acoustically rich performance hall rather than a studio…the musicians can interact with each directly. They can see each other, hear each other and make music the way music is meant to happen. Studios isolate the players, involve lots of machines (to restrict tempo, pitch and dynamics) and can take place over many weeks or months, if not years.

The recordings that I prefer are not attempts to recreate a live concert in your living room. I love tracks that maximize the emotional or intellectual connection inherent in the composition, performance and expression of the artists. Using current state-of-the-art recording and playback technology, it is possible to exceed the reality of a live music performance…at least sonically. The musicians in a surround mix are sitting around you in your space playing for you. For myself, it doesn’t get any better than that.


 



 

There has been a resurgence of interest in vinyl LPs during the past several years. Many audiophiles assert that vinyl LPs sound “warmer” or “more analog” than digital recordings...especially standard resolution compact discs. Even makers of high end digital audio equipment such as digital to analog converters and disc transports make the claim that vinyl is the reference to which all else is measured.

I was dismayed to read the “Back Page” interview in the most recent issue of The Absolute Sound. Neil Gader asked 10 questions of Paul McGowan, the CEO of PS Audio. Near the end of the interview Neil asked if vinyl was still the reference for audio fidelity. To which Paul answered, “Absolutely, I think digital struggles to come up to the standards that are easily attained by vinyl.” His opinion is widespread among audiophiles.

I do not agree with Paul or any of the other advocates of this position. If we were only talking about the sound of early CDs in comparison to LPs, then I might waffle on the point. It’s true that early compact discs were made from equalized tapes that were intended for vinyl and the emphasis and dynamic modifications made to the audio were ill-conceived and produced poor results. But in this age of high definition audio recording and playback, it is absolutely untrue that vinyl provides the reference against which all audio reproduction should be compared!

It is true that vinyl has a particular sound associated with it just as film looks different than video. Audiophiles have come to appreciate the sound of vinyl. The distortions of this very highly developed reproduction method have come to be known as “warmth” and “depth”. But they are distortions to the actual sound received by the microphones. I have no argument with the sound of vinyl among the various flavors that are currently available to music fans. Where I draw the line is when someone elevates vinyl to the reference standard. If by “reference standard” we mean sound reproduction that meets or exceeds the capabilities of our human auditory system. Vinyl doesn’t even come close...but HD Audio has the potential to.

Let’s first take a look at what I call the “provenance” of a particular recording. By that I mean, the specific production steps that a track goes through prior to arriving at your speakers. Music starts with musicians/singers performing in front of microphones and recording equipment (it’s true that a lot of electronic music is captured directly to the recorder without mikes but that’s a story we’ll address later). The original recording pretty much establishes the fidelity of the recording. These days there are some very sophisticated tools that can remove clicks, pops and hiss from older analog recordings. There even some state-of-the-art tools that can selectively remove the frequencies of say a cell phone from a piece of recorded music...but they are expensive and require a very skilled operator. That’s why I say the fidelity is “pretty much” established at the time the musicians played the tune.

In the past, ensembles would assemble in a studio or in a performance space and play. The audio engineers would strategically place as many microphones as they deemed necessary (minimalists prefer fewer mikes and others like the sound of many) around the space. The feeds were mixed together in a mixing console and the output (either mono or stereo) recorded by a disc cutter or on an analog tape machine. The resultant recording is referred to as the master. And if you wanted to hear that recording at its absolute best, you had to be present during a playback of the master in the control room. Otherwise, the next stage in the production process degraded the sound by about 6 dB (which is a lot). Analog tape copies lose 6 dB of dynamic range and signal to noise ratio when they are copied. There is even a term for this degradation. It’s called generation loss. The “safety” copy is used during the mastering and disc cutting process on the way to the vinyl master. Record labels and engineers simply can’t risk damaging the original master.

In the world of audio fidelity things like dynamic range and signal to noise ratio are measure in decibels, a logarithmic measuring system. Human hearing is the most sensitive of our 5 senses. Our ability to hear extremely quiet sounds AND tolerate very loud sounds is astounding (the amount of energy received by your ears from the quietest to the loudest is billions of times greater). Using decibels, humans experience pain and can suffer severe hearing loss if exposed to 145 dB. A full symphony orchestra cranking out the final variation in Mussorgsky’s Pictures at an Exhibition - The Great Gates of Kiev might hit 125-135 dB for brief moments (many woodwind players where ear protection if they sit front of the brass section). Standing in the front row of a Metallica concert produces sound levels that exceed 135 -140 dB for prolonged stretches.

So how good are the various recording technologies at capturing the dynamic range of the real world? Analog tape, the recording technology most often used in the production chain of a vinyl release, tops out at about 72 dB. If you use a noise reduction system such as Dolby SR (Spectral Recording) you can push that number up to 90 dB, but risk distortions to the harmonic accuracy of the recording. So the vinyl records that audiophiles claim as a reference are very limited in dynamic fidelity...never more than around 60-75 dB of signal to noise ratio can be delivered by an LP. Still they can sound pretty great...in spite of the limited dynamic capability.

HD Audio according to my definition is audio that is recorded and reproduced (both ends of the production chain must be included) with specifications that meet or exceed those of our human hearing sense. With regards to dynamic range, a PCM (Pulse Code Modulation) encoded audio track using 24-bit linear digital words has the potential to reach 144 dB of signal to noise ratio. In reality, the equipment we use falls somewhat short of this theoretical upper limit. Current state-of-the-art converters and recording machines spec out around 125-130 dB...still a whole lot higher than the best analog machines and vinyl reproduction. Each PCM digital bit equates to about 6 dB of signal to noise ratio according to the theory.

So a vinyl record (made from the safety copy) has a dynamic range of 60 -75 dB, which can be fully encoded with only 12-13 bits (less even than the 16-bits available on a standard definition compact disc). While an HD Audio project that is carefully done can accommodate 120-135 dB of signal to noise ratio within its 24-bits. From the dynamics side of the fidelity question, vinyl isn’t even in the ballpark.

We’ll talk about frequency response, linearity, timbral accuracy and timings issues in the next installment. But the next time you read that vinyl is “still the reference”, you’ll know better. Take the initiative to listen to a great HD Audio track...something with a lot of dynamic range...and you’ll know why I’m so passionate about this. The timbale on the Ernest Ranglin recording we did is a prime example. On vinyl it would have to be compressed to fit...on the HD Audio file or DVD, all of the dynamic range is delivered. It just sounds more real and contributes to the musicality of the track in a way that has previously been impossible.

There’s good news and bad news in the quest for high definition music downloads. The good news is that there seems to be a genuine move to better quality audio delivered via the web. The bad news is that the majority of “HD Music Download” services are offering only standard definition tracks. I don’t fault them for moving the fidelity bar up...we all need better music...but to claim that “CD quality” is HD is disingenuous and misleading.

Recently, there have been a number of articles published in print and online reporting on this exciting trend. If you pick up the new issue of Home Entertainment magazine, there is an article entitled, “Downloads on the Up and Up” by Dennis Burger. The subtitle is, “MusicGiants and iTrax give Internet music download an audiophile makeover.” It’s an excellent article on the emerging market for HD audio downloads.

Even TAS (The Absolute Sound), the gold-standard publication for audiophiles, placed a banner on the cover of their August issue...”The Digital Issue.” For a trade publication that caters to the very high end of the audio market and generally reserves its highest praise for expensive turntables, vinyl, tubes and two-channels, it was promising. Sadly, they missed the boat by focusing on CD quality music servers, download services and some magic potion that supposedly matches the “optical impedance” of the light reading the pits of your discs.

I do applaud Robert Harley for stating on page 59, “Although MusicGiants touts its downloads as “HD,” the files are CD quality. According to the company, the files are called “HD” because CD-quality files are “High-Definition” compared to MP3s and other lossy formats. In my view the term should refer to a sampling ate of 88.2 kHz or higher and a word length of 20 bits or more. It seems misleading to CD quality “HD audio.”

I couldn’t agree more. Audiophiles should be well beyond the world of compact discs at this point in audio’s history!  How about talking about real HD music servers and sites like Linn and iTrax. Robert even responds to a letter to the editor that, “high-res downloads are right around the corner” when they are, in fact, already here.

Even Apple’s iTunes site, the largest online store by far and the 2nd largest music retailer on the planet, is promoting its “plus” version of their catalog...encoded files at 256 kbps (remember that CDs require around 1400 kbps to achieve 44.1 kHz/16-bit fidelity).

Hardware companies are moving into this space as well. Olive Media Systems of San Francisco has focused on creating music servers and a networked home environment for distributing digital audio from a central hard drive. I’ve talked with them at length about a new piece in their Opus line of servers that will accommodate 96 kHz/24-bit playback. The new product should be available soon and will be among the first devices to handle true HD audio.

Logitech/Slim Devices has been delivering their Transporter for some months. It’s basically a high-resolution, two-channel Squeeze Box, their award-winning audio bridge device that connects a computer to your living room. It’s a solid product and runs at 96 kHz/24-bits.

If you’re more the do-it-yourself type...it’s not difficult to create a music server that can handle 96/24 stereo PCM files on a Mac or a PC. Shortly, I will begin a series of “how-to” columns that provides details on setting up a great quality music server for minimal money. I’m considering offering some hardware through iTrax to interested customers.

Linn, the UK-based hardware and record company, was probably the first to deliver recordings that were actually made using audio equipment capable of capturing a performance at better than CD quality. I applaud them for their groundbreaking move into the market with solid recordings.

Writers should be able to distinguish between “CD quality” downloads pretending to be HD and the real thing. Their job is to advance the knowledge base of music-loving consumers...not try and extend the lifespan of CDs. HD digital downloads are the future of high end audio.