Mixing, part 2 - Compression

Alright, so it's time we had a little talk about a little something called compression.

What is compression?

The short answer is that it's a type of processing that allows you to automatically control the loudness of your tracks. The type of device that allows you to perform this magical processing is called (wait for it)...a compressor.

For example, say you have a vocal track where the MC's performance is at a pretty consistent level for most of the song, but then he/she suddenly gets really loud at one part. In this case, compression could be used to just turn down the loud part and leave the rest of the performance the same. This is what compression was originally used for...

But, in most modern pop music, a TON of compression is used on pretty much every track. Why? Here are a couple of reasons:

1. To make things sound smooth (aka "clean").
2. To make things sound punchy (aka "slap").
3. To make the song loud.

So, if you want your song to have any of the above qualities, you should probably take some time to learn how to compress your tracks properly.

The basic concept is that you set a certain volume level on your compressor, called the threshold. If the volume of your track goes over the threshold, then the compressor kicks in and turns down the volume until the signal goes back down under the threshold. The amount it turns the volume down by is called the ratio. These are the two most important settings on a compressor - they tell the compressor when to start working and how much. Check it out...

The next two settings you need to consider are the attack and release. The attack tells the compressor how quickly to start working once the signal crosses the threshold. The release tells it how quickly to let go once the signal goes back below the threshold.

The last setting you should know is the gain, or makeup gain. This setting allows you to turn the overall volume of the track up. Why would we want to turn the volume back up when we just used the compressor to turn it down? Good question. The short answer: the slap factor. Think of the gain knob as the slap control. BUT, the slap control only really works if you've set the other settings properly.

Here is a picture of the Digidesign Compressor/Limiter that comes standard with Pro Tools software. It features all the controls we just discussed, plus a few that you don't need to worry about just yet. You can Insert this on any of your audio tracks:


Here is a general formula for compressing a vocal track:
1. Solo a vocal track and insert a compressor on it.
2. Set the Ratio to 5:1
3. Now adjust the Threshold until you see a maximum of about -6.0 dB of gain reduction happening in the column called "GR"
4. Set the Release to about 150 ms.
5. Now turn the Attack all the way to the right and slowly start turning it left (counterclockwise) until you hear the vocal just start to get muffled. Stop.
6. Now adjust the Release until you see the Gain Reduction moving nice and smoothly in time with the music. Close your eyes and listen. The volume of the vocal should sound pretty even and consistent. If you hear any sudden jumps, then you should try to adjust the Attack and Release settings until the jumps get smoothed out.
7. Turn up the Gain to 6.0 dB.
8. Hit the Bypass button to check what the track sounds like with the compressor on and off.
9. Now unsolo the track and listen to it in context with the rest of the song. Turn the bypass on and off to hear how the compressor is affecting the overall feel of the song.

Now, the formula above is a very general set of instructions and you should definitely try to adjust these settings to whatever sounds best on your music. I would recommend not using a ratio higher than 8:1. Try compressing everything from kick drums and bass, to digeridoos and Andean flutes. But just know this...

When you overuse compression, you run the risk of taking out all the subtle parts that make music sound human.

Some people say that almost all mainstream pop music these days is totally overcompressed and plastic sounding. I personally tend to agree, but this is the sound we're all used to hearing on the radio, MTV, etc., so it's getting hard for us to even imagine music sounding any other way.

I guess it's up to you to decide how to best use this tool to make your own music sound as good as it possibly can. At the end of the day that's the only thing that matters, so use your ears and always pay attention to what's happening to the song as a whole!

Mixing, part 1: Basics

So, at this point most folks have finished the majority of the recording for their songs. Now it is time to turn our attention to mixing...

Mixing is the second part of the process of producing a professional recording. This is where an engineer (usually not the same as the one who did the tracking) takes all the raw tracks and fine tunes everything to make the song sound as powerful, polished, and interesting as possible. Really successful engineers get popular because they have a unique "sound" that they bring to the music they work on.

Different genres of music tend to have different styles of mixing.
For example, most pop music (including most rock and hip hop) tends to use a lot of processing in the mixes to make songs sound LARGER THAN LIFE. Listening to pop music is almost like watching a movie. Like, Kanye West basically wants you to believe that his music is the product of a superhuman badass, so the mixing on his songs reflect that: everything hits really hard, there are lots of FX, etc.

With other types of music, like jazz and classical, the goal is to make everything sound as realistic as possible. You're trying make the listener feel as if he or she is right in the club or concert hall where the performance is happening. You don't want to add anything that sounds like it was artificially produced in a studio (even though the mix is happening in a studio!).

So, considering that most of you guys are pretty much making various forms of pop music, and most of your instrumentals were created "artificially" with software, which approach do you think you'll take?

When you're ready to mix you have a lot of ways you could approach it, but here is a simple formula for you to follow:

1. Pull down all of your faders and then bring them up, one at a time to build a good basic balance of all your instruments. Especially the melodic instruments (synths, samplers, guitars, saxaphones etc.). If you have a couple different instruments playing at the same time, then you have to decide which one is the most important and turn the other ones down, relative to that one.

*Note* Main vocals will almost always be THE most important thing in the mix and must be loud enough to be CLEARLY heard over the other instruments.

2. Pan all instruments at least a little bit to the left or the right. The only exceptions are kick drums, snares/claps, bass, and main vocals. Try to get a balance, so that instruments are spread out evenly between the left and right sides.

3. Clean up your tracks. Get rid of all the stuff you don't need, like the parts on the vocal tracks where the vocalist isn't performing. In Pro Tools, use the trim tool to get rid of the extra bits. Make sure you're either trimming to the zero-line crossing or using fades to avoid pops and clips! Use crossfades in the parts where you're sticking two regions together. I also often use high pass filters (HPF) at this stage just to get rid of super low frequencies that I don't need. (See Mixing, part 3).


4. Use compression to smooth out the volume levels of certain instruments and make them sound punchier (see Mixing, part 2 for more details). In a modern professional mix, almost everything will have at least a little compression on it. Most important things to compress: vocals, drums (esp. kick and snare), bass, guitars.

5. Use EQ to balance out the frequencies of all instruments (see Mixing, part 3). Possibly the hardest aspect of mixing to master. Good mixers know how to find specific frequencies from different tracks that clash with each other and then
dip or boost them to make certain instruments stand out, and put others more in the background.

6. Add FX to add space and interesting textures to certain tracks. The two most common FX are reverb and delay. Both of these add "echo" and make things sound like they are in a real acoustic space (a church, for example). More extreme types of FX include flangers, phasers, distortion, etc. As a rule of thumb, less is more when it comes to these. Check them out, experiment, but use them sparingly!

7. Automate tracks to give the song more flow and movement.
Figure out where it might help to bring the volume of certain tracks down. For example, maybe a certain synthesizer would be good to be low in the mix during the verses, but at the hooks you could bring those up to make that part hit harder. You can also automate panning and pretty much anything else to create interesting movements in the song's flow. Again, less is more!

8. Bounce your final mix out of Pro Tools!
Remember to bounce to whatever format the final tracks are going to be collected. For this class, bounce at:

Stereo Interleaved
Format: WAV
Resolution: 48,000 Hz
Bit Depth: 24 bit