Why are your mixes .mp3 files?

The most common mistake I'm seeing right now are mixes that have been file compressed. File compression is what occurs when you create an .mp3, .aac, or .wma file.

What is file compression? Well, according to this wikipedia article:

In lossy audio compression, methods of psychoacoustics are used to remove non-audible (or less audible) components of the signal.

Think about that - REMOVE NON-AUDIBLE (OR LESS AUDIBLE) COMPONENTS - do you want ANY of your audio removed? You've just spent how much time and money making a recording and you want a piece of software to just chop some of it off? I sure hope your answer to that question is "no".

Here's a spectrum analysis of a CD quality song, what you see here are a bunch of colored lines indicating the intensity of frequencies from the low end on the left to the high end on the right. This song is utilizing all of the frequencies we can hear from 20 Hz to 20,000 Hz (or 20 kHz).

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Here's what the same song as an .mp3 file looks like:

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See that white line with the number 12.07 kHz? The colored lines have a sharp drop there, that's because there is no audio above 12 kHz. I'm pretty sure you want to keep that portion of the audio spectrum, don't you?


How do we avoid this happening to our mixes? Well if you know what you're doing then it will never happen, ever.

I am fluent in Pro Tools so I'll speak to my knowledge there, but the process is generally the same whether you use Pro Tools, Logic, Cubase, Nuendo or some other DAW.

When you bounce your mix out of your DAW you will want to create .wav or .aif files. The bit depth and sample rate will vary depending on those settings for your session. If your session is at 24 bit 48 kHz then feel free to bounce your mix at the same settings, however, never select anything less than 16 bit, 44.1 kHz as this is the audio CD standard and you won't want to go below this. Oh, and make sure the output is set to "Stereo Interleaved" that way you get a single file on your drive, but it's a stereo file. The other acceptable option is "Multi Mono" which as you might guess creates two files a .L and a .R for the left and the right channels of audio. This is fine, but I find it easier to keep up with a single file rather than two.

Now you have a folder with some mixes. How do you get it to your mastering session? If your mixes are 24 bit an audio disc is out of the question so you could put them on a USB drive, burn a data disc, or FTP them to the studio. If the mixes are 16 bit 44.1 kHz you can just burn an audio disc. Ahhh, but how do you plan on making that audio disc? Do you have a dedicated CD burning software? Something like Nero (pc), or Toast (mac)? One of these would be preferred, and if you use them you will generally have no problems at mastering. The problem comes when clients try and use one of two main pieces of software that will transform their mixes without them even knowing it.

They are iTunes and Windows Media Player. Let's take iTunes as the example since the same basic thing happens in WMP. In order to burn an audio disc in iTunes you have to import your files into your iTunes library. When you do that, iTunes converts your files to match the import settings that are selected in the preferences of the application.

Here's where you find the Import Settings in iTunes:

Under the iTunes menu select "Preferences" this is the window you see:

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When you click "Import Settings" you see this window:

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The default option when you install iTunes is the .aac encoder. Not unlike .mp3 compression .aac will file compress anything that you import into iTunes.

Once you've imported your files into iTunes you can burn a disc and think everything is fine, because, hey, it's an audio disc that means it's 16 bit 44.1 kHz, right? Wrong. Once a file loses that audio in the file compression stage it can never be brought back.

If you have to burn an Audio CD for mastering and your only software choice is to use iTunes, you'll have to change you're import settings to either the AIF encoder or the WAV encoder, also make sure that the "Settings" for import are set to 16 bit and 44.1 kHz. This will ensure that you import CD quality files into iTunes.

You should always strive to maintain the highest level of audio quality from start to finish of your project. Hopefully this helps achieve that goal.