Mastering the Music Domain

For those who enjoy recording their own music or podcasts at home, mastering is one of the more little known aspects of the process. Most people are aware of overdubbing, editing and mixing, but comparatively few understand how critical mastering can be to add the final sparkle to a mix, how it can transform a pretty good mix into something amazing, or (sometimes, with a little luck) a poor mix into something tolerable.

In the professional world, mastering is usually done using lots of very expensive outboard gear, as the final step before a master copy of a CD is sent to be duplicated into millions of consumer discs, or an album of MP3s is uploaded to iTunes and Amazon.

In the not necessarily professional world of home recording, mastering can be done with a plug-in effect.

For over ten years, Boston-area iZotope Inc., located near Boston has been producing a high-end plug-in for recording programs called Ozone. Now in its fifth iteration, iZotope produces versions of it for most PC and Mac-based recording programs, as well for Pro Tools, the most popular professional recording system.

When I interviewed him for a Blogcritics article on an earlier iteration of Ozone back in 2004, Jeremy Todd, the company’s chief technology officer (and a musician himself — he was trained as a classical pianist) told me:

Mastering in general is tough to put your finger on; I guess it depends on who you’re talking to. But for the purposes of Ozone, we talk about everything that you do once you’ve got a stereo mixdown, to when you when you actually have a master and you say, “OK, this is the audio, this is it, we’re not touching it anymore.”

With Ozone, we try to include everything that someone would need, so that, while it’s not always the case, but in theory they could not use another plug-in; they could do it all in one.

How was mastering done before the days of computers and hard disk recording? Todd says:

There were trends established way back when, that are still present today. We’re still seeing examples of these standalone hardware devices. Things were much more isolated, you wouldn’t see as much all-in-one gear, and you’d have these big, honking pieces of equipment that were just an equalizer — and a two or three band equalizer at that, usually just a finalizer, a loudness maximizer.

Obviously, if you go back far enough, mastering was dominated by analog equipment. So with Ozone, we’re trying to capture some of the flavor that people liked, which was a big challenge when it came to designing the DSP. It’s very difficult for people to explain why they like their two-band analog equipment. So it boiled down to a lot of listening tests, and asking people a lot of questions.

We tried to keep a little of the analog flavor in the sound, in our previous versions of Ozone. [Beginning] in Ozone 3, the analog modeling was firmly established, but people have been saying that in some cases, they want something cleaner; they don’t want any flavor, they want to be more surgical with the tool. So we added a digital component to the equalizer and the multi-band crossover.

With Home Recording, Mastering More Important Than Ever

Let’s take a moment to discuss how the mixing and mastering process has changed over the past 30 years for the average home recordist.

Back in the 1980s, when I first began to record demos of songs for my local rock group on a four track, mixing was relatively easy…because there were only four tracks (that’s actually a bit of a simplification — I used a fair amount of virtual tracks and outboard gear). But I did all the mixes in real time and hoped for the best. For their time, they weren’t terrible demos — but certainly nobody would confuse them for properly mixed and mastered track on a CD.

By the late 1990s, it was possible to replicate the process on a personal computer — and with infinitely more control over the individual tracks and the overall sound.

Mixes on a computer are preprogrammed ahead of time. All of the fader moves that used to be done in real time as the mastering tape was rolling are programmed in ahead of time. The result, ideally, is a perfect mix.

But there’s less room for error. Analog distortion can be warm, wonderful stuff. But digital distortion is harsh and nasty.

At the end, all of this work pays off, when ideally, the completed track belays its homebrewed Army of Davids origins. But for me at least, getting there was a fairly steep learning curve.

And these days, DAWs can be doing double, maybe even triple-duty — I use mine to record song demos, to produce podcasts, and to edit the audio on video productions. And I’ve used Ozone at various times on each of these efforts over the years. (Including using it to master PJM’s Sirus-XM radio show that ran from 2007 through 2010.) And while this is primarily a review of Ozone, it’s worth mentioning that iZotope’s RX product is an excellent stand-alone program for cleaning hiss, clicks and other background funk from individual tracks for podcasts and music production — and does an excellent job removing hum from phone calls and instrument tracks. I’ve been using it on almost telephone interview I’ve produced since 2007.

Learning the Basics

While there are numerous books on the subject (I’d recommend Mastering Audio by Bob Katz), an excellent  manual on the mastering process is available for free as a PDF file at the iZotope Website.

It’s designed to be readable to even those who don’t choose to purchase Ozone. It may be the most readable manual to accompany music software that I’ve ever seen. If you’re a computer tech writer or software developer reading this post, you could do far worse than to copy the style of the Ozone manual for your product — it’s that good.

And the software itself isn’t too shabby, either.

You could easily spend hours tweaking the patches and presets in Ozone, and its unique interface. But some of those presets sound excellent stock. I found myself using the stock “CD Mastering with Exciter and Widener” preset frequently but dialing back some of its exciter plug-in, as its stock preset seemed to make the high end sound of my mixes a bit harsh.

Todd says, “In the guide are a few references to some genres and presets to use as a starting point. We found that most of the newer users, maybe for the first couple of mixes, will stick with a preset and maybe tweak it just a little bit. But after a while, everybody tends to tune their ear to what they’re looking for. And eventually many users make their own presets, for their own styles of music.”

Is it a perfect applet? Well, as I said, some of the presets can be a bit harsh sounding without any tweaking. And make sure you have plenty of RAM in your computer if you’d like to use it as a plug-in on a single instrument or track. (Recently, iZotope has released a plug-in called Alloy, which is designed to be a more processor-friendly compliment to Ozone, adding additional sheen to individual tracks in a mix during the recording and mixing process.)

And early on, I noticed that because of the intensity of the compression and loudness maximizer and other effects, fadeouts that I’ve programmed on a track before running it through Ozone often need to be adjusted. Ozone hears the volume going down, and its first thought is “push it back up!” Which you may need to compensate for when mixing.

But those are pretty minor faults, all things considered. Anybody who wants to take his or her songs’ mixes to the next level could do far worse than checking out the free demo version of Ozone.

(An earlier version of this article appeared at