The music industry, like most things in life, is ruled by a simple truth: A recording format is only the best until something better comes along.
Until now, many people would have defined the best as compact discs. But now something better has come along-an improvement in the way CDs are recorded, thanks to a refined mastering technology that improves the sound.
The technology is called 20-bit mastering, and it works like this: Bits are to CDs what grooves are to vinyl records; they hold the music. Until now the industry standard has been to master-that is, to place the music on the CD-at a rate of 16 bits of information. The additional four bits increase the range of the signal so the music sounds clearer, with less hiss.
These CDs, in stores now, are fully compatible with existing CD players and-this must be a first-cost no more than regular CDs. (An exception is Sony’s special gold-plated Mastersound line, which has re-released classic albums by the likes of Boston, Billy Joel and Janis Joplin for about $30 each.)
Sony undertook one of the most ambitious 20-bit remastering projects when it reissued all 12 of its Aerosmith albums, the bulk of the band’s catalog from 1973 to ’82. The discs arrived in stores in September.
The good news aside, don’t buy a 20-bit recording expecting an epiphany of sound. What you’ll get is a cleaned-up CD-a good remastering job that may reveal a wider range of high and low notes.
And you won’t be taking home actual 20-bit CDs, either; your player is capable only of playing 16-bit discs. But you still get the benefits. To make 20-bit recordings compatible with 16-bit CDs, Sony created a process called Super Bit Mapping.
Vic Anesini, 29, the mastering engineer on the Aerosmith project, explains: “The higher (the) number of bits, the better the resolution. It also helps expand your dynamic range (the difference between the lowest and highest audible frequencies).”
There are numerous ways to accomplish that task, but sound is often compromised, Anesini said. Not so with Super Bit Mapping, which reshapes the additional four bits-which contain sounds at the very high and low levels of the range-and lays them back into the audio signal.
So, how do the remastered CDs sound? In the case of Aerosmith, mostly pretty good. Side-by-side comparisons between the original and the new 20-bit versions reveal a clarity and crunch to the music where there had been mud and hiss. The difference is most obvious on the oldest release, 1973’s “Aerosmith,” which features the hit “Dream On.”
“I’m sure the original mastering houses, when they cut these things (for vinyl) were going from the original master (tapes),” Anesini said. “But the CDs have come from copies.”
That’s been a sore point since CDs were introduced in 1983. As record companies scrambled to get CDs on the shelves, that often meant recording the music from second- or third-generation sources rather than the cleaner-sounding original master tapes.
This remains true in the case of 20-bit technology: Any remastering is only as good as the tape it’s made from.
Two companies are trying to remedy that, using gold-plated CDs, which are said to have better laser reflection capabilities than standard CDs-Mobile Fidelity Sound Lab (under the Ultradisc “Original Master Recording” line) and Digital Compact Classics (DCC) press classic albums on gold-plated CDs.
Sometimes the technology is successful (Steely Dan’s “Gaucho” on Ultradisc is clearer than the original CD version); sometimes not (a somewhat muddy version of Elton John’s “Goodbye Yellow Brick Road,” also on Ultradisc).
The original two-CD set of “Goodbye Yellow Brick Road,” released by MCA in the mid-’80s, has brighter sound (but substandard packaging) than the $35 Ultradisc version. But the current Polydor single-CD reissue, off the original master, is the best deal-top-notch sound at standard prices.
Should you rush out and replace all your favorites with 20-bit versions? The sound differences are subtle. If you’re a serious fan and have an elaborate stereo setup, you might appreciate the slightly cleaner sound. A casual listener, you might not be able to hear the difference.
