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The Myth of Digital Sound - By John Vestman
Myth: Digital sound doesn't loose quality when transferred. There has been a long-held thought that digital can be transferred, cloned, copied, backed up etc. and the sound stays the same. Numbers are numbers, right? They are... if they stay *exactly* the same, but in the world of moving media/disks/tapes/digital consoles, they don't stay exactly the same in many cases. Bits can sonically byte the dust! What? Jitter, errors, and recalculations can change the sound.

This is a controversial subject, but if you want your masters to sound the best they can, it's worth looking into - vs. just assuming any one theory. A long time ago I assumed that if I transferred an audio file from one hard drive to another, it would sound exactly the same. I found out differently - of course I didn't know at the time that computer power supplies and grounding issues can cause audible jitter.

We'll come back to that. Here's some experiences you may have had: Computers crash. Hard drives lose data (especially when they fail). Files get fragmented (mostly slows access, may cause crashes). Norton and other utility programs are popular ways of recovering corrupted files. If all the one's and zeros worked perfectly every time, none of these problems would occur, since each file would do exactly as it was supposed to do each and every time. While software can be largely to blame, there are physical reasons that formats like DATS and CDRs are just plain error-prone. Error correction helps, but when it comes to your master, you want the ultimate... not second-best.

Set up: We are "imprinted" with the experience of analog music media. In other words, we are accustomed to an analog signal remaining the same when an analog volume control is moved. We are used to analog equalizers that shape the waveform vs. digital processors which internally recalculate the numeric data which creates an entirely new set of numbers (word length changes, etc.).

Granted, digital does what it does well because it sure is convenient and it's put recording studios into the hands of a lot of people. It just has a different set of limitations that we weren't expecting when the technology came out. This is the same thing that occurred when we discovered that solid-state electronics didn't have some of the cool sonic qualities that tubes did.

SHOCK: Dat safety "clones" don't sound the same. Unless you are using a high-end digital cable ($350 to $700) that eliminates cable reflections, or you are syncing your machines to a word clock unit, DAT safety "clones" will sound more brittle in the highs, and have less depth in the reverbs and room sounds. It's a more "dry" sound caused by digital jitter. All ADAT owners I know don't like the sound of their backups as much as the originals, which can be the pits if you're getting dropouts on your originals due to tape wear.

Reclocking can help... but here's a better idea - when you're mixing, make two first-generation real-time passes on different tapes of each mix (one client of mine told me he mixes to Panasonic, Sony, and Tascam dats simultaneously because dats aren't 100% compatible on different decks). I know. It takes more studio time. The four extra minutes (ok maybe 15) it takes to make that 2nd copy is worth having a 1st generation back up, especially if you're sending it out of state to be mastered. Compare that 15 minutes to how much time you spent tracking that song.

Different cdrs sound different. Even within the same brand. Their error rates vary, even with the kind of cd burner used. I've listened to Kodak's gold-on-gold "Writeable" cdrs, their gold-on-gold "Audio" cdrs, their gold-on-gold "Recordable" cdrs, their platinum-on-silver cdrs.... even Maxell 700 mb silver cds sound different from the Maxell Pro or Maxell "Music" cdrs. TDK's sound different from the Memorex's, Mitsui's, Verbatims, Sony's... and the bargain-basement cheapies are lucky if they even play! (If this concept pushes your computer buttons, be sure to read this whole article.)
My favorite: Maxell 700 MB silver top for more detailed highs, Maxell Music gold for a fatter, more solid mid-to-bottom. Fuji 80 Minute Audio cds are my next favorite, Sony and Memorex 700 MB are close, the BASF is in there... experiment and see what you prefer!


Important: If you're cutting cds on a home computer, to get fewer errors, don't use the gold ink-on-the-bottm cdrs - use the green ink ones because gold ink cdrs require a more powerful laser than many cd burners have. I find the 700mb sound better than 650 mb, and there may be better quality if the cdr manufacturer claims it handles higher burn speeds.... but....

Burning cdrs at 2X sounds different than 1X. I invited a professional engineer and a stereophile guy to listen to the same album on two different cdrs... one cut at 1X one at 2X. The engineer preferred the 1X, and thought the cdrs had different mixes on them. The stereophile guy simply felt the sound on the 1X was sweeter and wider. Burning cdrs at high speed (like 2X, 4X, etc.) adds hardness and sterility to the highs and mid-highs because the data isn't transferring as smoothly. (One client of mine would have been better off using his 12X-copy "master" as a Frisbee... it had major artefacts that were expensive to remove). If this Frye's your circuits, click on the links below...

Make sure if your first-generation master mix is onto cdr, burn it at 1X. On my cdr masters, I make sure that I include the instructions, "Cut glass at 1X ONLY." Even though some pressing plants will say that cutting a glass master at 2X creates fewer errors (and saves them valuable glass-mastering time), I insist on 1X, just as all the major mastering guys do. And keep your bits high - 24 bit sounds better than 16 bits... well then... analog sounds better than either in most cases...

One studio owner asked me why a cd copied to his hard drive and then just burnt to cdr sounded so different. I got some input from a computer programmer: Software designers are sometimes required to program for efficiency instead of precision. This means in order to make a program run fast at a competitive price, they end up making it handle larger blocks of data at once, compromising the possible resolution of the sound. A small error within a block gets corrected, and thus the whole block is changed.

I've experienced transferring a sound file from one hard drive to another changes the sound slightly (there are others who have not found that to be true on their systems). I know of a top music editor for film in LA who only uses one brand of hard drive because he can hear the difference between brands. Like I said, this is a highly controversial issue, with quite a few high-end computer professionals bringing forth a challenge: Changes and errors in data can occur in many instances, but not for WAV files... but wait... is it possible that different containment, location and physical access characteristics make a difference in the sound, even if the file is an exact clone? Some say that the file goes from hard drive to buffer before getting to the i/o card, but could there be other factors? Stay tuned as the Digital Mystery evolves and more tests are reported here...

Meanwhile: The Pro Tools studio next door did an experiment with me. We took a digital cable directly from his rig and recorded a song into Sonic Solutions. Next we took the same mix and loaded it into my system off a cdr cut directly on his computer (a difference of one digital generation). We then compared the sound of the two files on my system. AMAZING. The exact mix brought in via the direct cable version sounded fuller, wider, smoother, more open, more detailed, more musical and expressive. The cdr version sounded choked, grainy, and had less width. It wasn't even subtle, and all three of the engineers in the room agreed.

If you are recording from a digital source like a computer or a hard drive system like the Roland 1680 (Akai's and Tascam's are my favorite) onto a DAT or stand-alone cd burner, be sure to use the best digital cables you can afford. Cables make a significant difference - a $350 SPDIF cable makes as much difference as a $3,000 converter.

I also recommend if you're a musician/studio owner, that you are remembering that none of this technical advices means as much as the heart and soul of your music - your musicianship - the actual thing that all of this stuff is designed to reproduce and deliver to the audience who wants to hear you. When you're considering upgrading to the next piece of gear... consider if additional practice will improve your sound... even more than the slick new feature-filled Platinum Pro Version 39 Giga-Gizmo!



John Vestman is a veteran mastering engineer with over 26 years in the industry. His credits include: Hole (Courtney Love), Juice Newton, Ambrosia, Andre Crouch, The Wynans, Great White, Candyman, Billy Davis Jr./Marilyn McCoo and more. John Vestman Mastering is located in Orange County, California, and his web site http://johnvestman.com offers over 40 pages of information about successful studio recording techniques and sound philosophy.



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