I have heard the future and it has already been here for quite a while. For years, when I wanted to listen to recorded music, I’d walk over to the shelves housing my music library and select a disc to play. Whether a vinyl disc or a polycarbonate CD, it was always a physical disc, which needed to be retrieved from the shelf, removed from its cover and placed on (or into) the player. Note the operative word there is was. I’m talking about the integration of the home computer and the music system—in other words, what is also called a “music server.”
Music servers can take many forms. The music stored on them can also take many forms, as can the user interface. At its simplest, think of song files loaded into a program like iTunes. Some companies are now making dedicated hardware servers, essentially hiding the computing guts within a somewhat traditional looking component. The only giveaway might be the little display screen on the front of the box. Otherwise, it could be confused with any electronic component with knobs and/or buttons on the front.
The music files played by the servers come in a wide variety of formats. First there were the early “lossy” formats, such as mp3. In order to shorten download time and minimize the amount of storage space required, these formats shrink file size by throwing away information. Some lossy files can contain as little as less than 1/10th the information on a CD (!) while others contain about 1/5th the information on a CD. These formats can be convenient for very fast file transfer via the Internet, such as when sampling tracks from an album. However, one must pause at claims from some quarters that removing 80-90% or more of the information on a CD results in something that sounds the same as that CD.
More recently, a number of so-called “lossless” formats, such as .flac and .alac, have become popular. These too, seek to shrink file size, though in theory, they are able to reconstruct the missing data upon playback, rather than simply throwing it way. (There is some debate as to whether the results actually sound like the non-reduced original. To my ears, they do not.) Lastly, there are the raw, non-reduced PCM formats, such as .aif and .wav and also the variations on an even more recent format, DSD. All of these raw formats require more storage capacity, as the file sizes are not reduced. However, with the price of storage coming down every day, this is simply not an issue for many listeners, who prefer the performance of the raw formats – the same formats in which the recordings are originally created, mixed and mastered.
So let’s say you’ve selected a computer (and server application) or hardware player. The next step is to build your music library. Music files can be purchased as downloads (or files-on-disc) via the Internet or “ripped” from your own music collection. “Ripping” is the term used to describe the extraction of music files from a disc, such as a CD. Some of the music server programs, iTunes for example, have ripping functions built-in. A number of dedicated ripping applications are available for free on the Internet. Digital discs are not the only source music lovers are using to get files into their server libraries. Many vinyl enthusiasts will create “needledrops” by digitally recording their favorite vinyl records.
With all the files installed in your server, what next? What does having a music server mean? In my experience, the shortest answer is that having a music server will change your relationship to your music collection and it will change the way you listen, both of these in very positive ways. First, let’s say you want to hear a particular album or a particular track from a particular album. The music server isn’t just a player, it is a database too. Type in an artist’s name or the name of a musical track, hit enter and you can be listening to music in a lot less time than it would take you to walk to the music shelf, much less find the disc, put it in the player and press Play. But there is so much more. Typing in an artist’s name will show you everything in your library by that artist. Typing in a track name will show you every version of that piece of music in your library. There are countless variations, all dependent on what is called “metadata”.
Metadata is the information that accompanies each music file. Many server applications will automatically fill in a lot of the metadata for each track. For example, when you rip a CD from your collection, the server application might check the Internet and fill in all the artist, song and genre information, perhaps also adding composer, year of release, or other information, including the cover art. For those who want more details, many programs allow user entry of metadata as well. (I like to include who played what instrument for the jazz albums in my collection.)
With the right metadata, the music lover can search their library in almost any way they can imagine. Sometimes I like searching by composer, particularly among jazz standards but also among the other types of music in the collection. Or, I might just enter a genre, say, if I’m in a mood to hear some rhythm & blues. The point is, with this sort of capability, other ways of approaching the music library come to mind all the time. And sometimes, I’ll just set the server to “Shuffle” and let it pick the next tune. This has resulted in some very pleasant surprises and the rediscovery of old gems in the collection.
So, what is the sonic price of all this convenience? Just how much does one have to give up compared to what they can get from a good CD player? Well, assuming the music library is comprised of at least CD resolution files and not just the lossy files still popular among the larger download services, this is where it gets really good. Or rather, where it can. At its simplest, a server can be used with the speakers built into the computer or with small, powered desktop speakers. (Lossy files can be fine in this application because the playback hardware is limited anyway.) However, if instead of taking the sound from the computer speakers, the signal is taken from the server in digital form, it can be fed to an outboard DAC (digital-to-analog converter). The DAC in turn, can be connected to a full size audio system.
What I’ve found is that when CDs are ripped to a raw PCM format (I tend to favor .aif, which is the same format in which I record, mix and master), when both the CD in the player and the ripped file in the computer are fed to the same external DAC, there is not only no tradeoff but in fact, playback from the computer beats the CD every time.
Ever since I mastered my first CD back in 1983 and compared what came back from the replication plants with the masters used to make those CDs, I’ve found that CDs from different plants (sometimes different lines within the same plant) all sound different from each other and none sounds indistinguishable from the master used to create it. This is true regardless of the CD player or transport used, regardless of price or design. To my ears, comparing playback from disc with playback of the master used to create said disc, there are always losses of focus and fine detail, sometimes subtle, other times not so subtle at all.
Interestingly, when those same CDs are ripped to computer as raw PCM files and then compared with the masters, all the differences go away. In other words, with playback of these files via a good server, for the first time in my experience, the user can have the sound of the CD master at home. So, the convenience of a music server not only does not exact a sonic price, the results actually sound better than playback from a disc player or transport. (It might not beat good vinyl playback in some ways but that is a subject for another day. And besides, what I’ve outlined above is only the beginning. Read on.)
But wait, it gets even better. Music via a server is not limited to CD resolution, which in fact, might be seen as the “cassette” of the digital world. (I will leave to the reader what this says about the lesser digital formats.) Music servers make possible what has previously only been available via some of the post-CD music formats, such as DVD-Audio or SACD. Here again though, the differences between playback from disc and playback via a server come down in strong favor of the latter. The quality ceiling at this point, is determined by the resolution capability of the DAC.
The resolution of a digital file is determined by two factors. The first is its “sample rate” (how many times per second the original sound is converted into a digital sample during recording — think of frames per second with motion pictures, each frame being a “sample” of the video motion). The second factor determining the resolution of a digital file is its “word length” (how many digital “bits” are used to describe each sample). CDs carry 16-bit, 44.1kHz audio (sometimes abbreviated as “16/44”), which means each digital sample is described with 16 bits and the original sound is sampled 44.1 thousand times per second.
Some music is now available in 24-bit formats (as opposed to CD’s 16-bits), with sample rates of 88.2 kHz, 96 kHz, 176.4 kHz and 192 kHz (as opposed to CD’s 44.1 kHz). While 24/96 recordings can certainly sound much more realistic than 16/44 CDs, it is with the highest rates (I’m thinking 24/176 and 24/192 recordings) that a threshold is crossed and with the finest DACs, I have experienced something I’ve sought for as long as I’ve been an engineer but never attained until now. That is, when at recording sessions, I have not yet been able to discern the recorded sound from my direct microphone feed. This is something I’ve never experienced with any of the finest analog formats or with any other digital format.
Given 24/192 files on a music server, in raw PCM format, the listener now has, for the first time, what is essentially the recorded master itself. Note that the finest modern recordings are made at resolutions considerably higher than CD. In order to create a CD master, the sample rate must be converted (reduced) to 44.1k and the word length must be reduced from 24-bits to 16-bits. A good rip from CD can bring home the sound of the CD master but the 24/192 files will contain several times the amount of information that 16/44 CD is capable of holding. It is the difference between the CD master and the high resolution master itself.
I started this entry by saying “I have heard the future” and that is what I said out loud when I first experienced my music via a server: “This is the future!” Many young listeners have never known disc playback. For them it has always been downloaded files played on the computer via a program like iTunes or played via their iPods. As more mature music and audio enthusiasts got into the idea, a number of designers catering to this market started to offer higher fidelity options and the market for “high res” downloads (and files-on-disc) is really just getting started. There are even services that will take an existing disc collection and rip it to computer drive for a per-disc fee. Several years ago, I remember hearing the term “convergence” used a lot to suggest an expanded role for computers (and computing machines) in our lives. Music servers are a great example, fundamentally altering how music lovers interact with and enjoy their music collections.
The Soundkeeper 