If you read CD or LP credits you've probably seen "Mastered by Greg Calbi" a bunch of times, but don't have a clue exactly what Calbi and other mastering engineers do. I don't blame you, it's a mystery to most music lovers. When I heard that Calbi was going to cut some LP masters I made arrangements to drop by Sterling Sound and watch the master masterer at work. He's mastered thousands of records; everybody from Bob Dylan to Talking Heads to The Roots, to the "High School Musical" soundtrack, and one of my favorite records from last year, Yo Le Tengo's "I Am Not Afraid of You and I Will Beat Your Ass." As a matter of fact, he's mastered all of Yo Le Tengo's CDs and LPs of the past 10 years. He must be doing something right.

In the early days CDs were typically mastered from the LP master, Calbi explians, "It wasn't until the mid '80s that we starting mastering for CD. Vinyl was still number one; CD and cassette masters were taken from the LP master."

Nowadays remastering can refer to a redo of a CD master, going back to the original tapes/files and giving them another listen and eking out better sound. Calbi remastered Bob Dylan's "Oh Mercy" CD a few years ago, but he also mastered it the first time in 1989. The first mastering was digital all the way, but for the remaster Calbi introduced analog tools (equalization, analog tape machines, etc), and that resulted in a much better sounding "Oh Mercy" CD and SACD.

In any case Calbi works from the final mix and fine-tunes the sound with equalization, dynamic range compression, and volume level adjustments. The mastering engineer's entire signal path--playback machines, equalizers, black boxes, etc--all influence the finished product's sound.

Still, you might wonder why the engineers don't just transfer the final mix and master CDs or LPs from that, but the sound benefits from a fresh set of ears. The mastering engineer perfects and completes the mixes, or as Calbi put it, "Mastering is finishing for a specific format, CD or LP." What about MP3? "That's very different, and not just from a sound quality point of view, It's assumed that MP3s will be heard in shuffle mode, competing against unknown music." Right, and that leads to extreme dynamic range compression; so all of the music's natural soft-to-loud dynamics are squashed flat; MP3s have to be loud all the time because with MP3s everyone is screaming for attention in a crowded market.

CDs and LPs are also different in that they're conceived as complete works, and their mastering balances are affected by the songs' sequence--how the songs sound next to each other, the key changes, the rhythm--all sorts of things are compensated for by the mastering engineers. They have to see, correction, hear the big picture.

The mastering engineer is the final critic of the mix, and uses his/her knowledge to try and improve it. And now that so many projects are recorded in home studios by inexperienced engineers there's even more of a need for a fresh set of ears to tweak recordings.

What about iTunes? I ask Calbi about the rumors about the Beatles catalog being remastered for iTunes. He was ahead of me, "They're not being remastered just for iTunes; they're being remastered because they got a deal with iTunes. I was partially involved the discussions leading up to the remastering sessions, most of the Beatles catalog hasn't been remastered in 20 years." It's likely the new remasters are destined for CD release.

Cutting the Michael Powers' record at Sterling Sound.

(Credit: Steve Guttenberg)

Watching Calbi at work, mastering this killer blues rock LP, "Onyx Root," by Michael Powers, there's no doubt the man enjoys his work. Calbi's grooving to the music, swaying back and forth in his chair. His playback system is very audiophile, with massive Energy speakers and an Audio Research vacuum tube amplifier the sound is so good I feel like I'm listening to a live performance.