“Mastering Engineer” — an industry job shrouded by a magical black veil of intrigue and mystery. Who are these guys? What do they do behind those closed doors that makes your music sound so good? Why might you need one — and why can’t you just use a piece of mastering software to replace them?

Before moving forward, let’s take a step back. One of the hardest things for any recordist/engineer/producer to do is to make sure all the frequencies of your mix are even and balanced. Think of the many variables that might throw you for a loop in that department: your speakers, the room they are in, the desk or stand they are on, the software you’re using and the hardware it’s running through…. All of these factor into the final mix’s equation. That’s not to mention your own ears, by the way, which may or not be as finely tuned as you’d like to believe.

Tuned Rooms

A poorly balanced room or set of speakers may lead you to mix your song with too much or too little bass, mid or treble. Did you ever finish a song in your room that you think is perfect, but then you take it to your friend’s house and it sounds terrible? That’s probably the result of your own setup not offering a true representation of what’s actually been recorded.

One of a mastering engineer’s primary jobs is to check and fix your mixes in a tuned audio room that has been designed to do nothing but that. It takes a lot of hard work, attention to detail and often a substantial financial investment to make sure every single aspect of a mastering room offers an accurate reproduction of your music. That’s what they mean by a “tuned” room: the sound is perfectly balanced out of the (often ridiculously expensive) speakers.

Most quality mastering engineers know their room incredibly well, so they can easily make sure your mixes are even in the lows, mids and highs. They can also level out the volumes to make sure all the mixes sound balanced and even.

Mastering Packs a Punch

Typically using a combination of high-end analog and digital gear (such as equalizers, limiters, compressors and noise reduction units), they can sculpt the final sound of your mix to be one that will sound great whether it’s playing back on huge speakers or on a tiny pair of ear buds connected to an iPod.

Aside of the sonics, mastering engineers also space the songs in the mix order. Then they prepare a final disc or set of files (a master) that duplication houses can use to create CD’s. Even if you’re not making CD’s, a good mastering job still gives you the best shot at making sure your mixes pump through those speakers.

Man vs. Machine

Yes, there certainly are software programs available that let you master your own tracks. Some of them are quite good, too. But make no mistake: the trained ears and experience of a fine mastering engineer, along with a perfectly tuned room, cannot be replaced.

Still doubtful? Send just one of your mixes out to be mastered and then A/B it with your original. If you’ve hired a good engineer at a reasonable price, you’ll see that the difference is worth it. It doesn’t have to cost an arm and a leg, either; certainly less than having your own room acoustically calibrated and equipped for mastering.

Plus, it’s an invaluable experience when the sound coming out of the speakers finally matches the music you first heard inside your head. There’s a good reason why nearly every hi-level commercial release is sent off for mastering before it hits the public’s ears.

–Rich Tozzoli

Rich Tozzoli is an accomplished engineer, mixer, producer and composer. He has worked with artists such as Ace Frehley, Al DiMeola and David Bowie, among many more, and is the author of Surround Sound Mixing for ProTools. Rich is also a lifelong guitarist and composer. His work can be heard regularly on FoxNFL, HBO, and Discovery Channel.