What is mixing?
What can it do for my audio? Audio mixing is one of the most intensive steps in recording.
When you bake a cake, you take the flour, sugar and eggs (whatever they put in!) and mix them all together. This brings about the final product, a finished cake.
When you do this to audio, you take several audio tracks and combine them together into one.
That is the very basic essence of the process, but here are several things you can do:
- Levels and Pan
- Digital effects
- Bouncing to disk or tape
- Hardware and Software mixers
Levels and Pan
Levels and panning are two of the most basic tactics used by audio engineers.
The level of a track means how loud it is compared with the other tracks. Normally in digital recording the maximum level is 0 db, which is the top of the ladder.
Most mixers let you set the level up to +6 db. That allows you to gain some extra volume for an individual track, but beware of putting all the tracks up! Here's why...
In digital recording, 0 db is the loudest a signal can go. If it attempts to go above that, it is cut off at 0 db, making a harsh sound known as clipping.
If you adjust all of your tracks up to high, you will probably get clipping, and it doesn't sound nice!
Pan refers to the left-ness or right-ness of a track in a stereo mix.
A stereo track has two channels, left and right. When played by two speakers side by side (or a set of headphones), you can get a stereo image by panning a track all the way left to play out of the left speaker.
When you have a bunch of tracks, you can use panning and levels to make it sound fuller, and also create a soundstage.
That refers to how the tracks are perceived by the listener. A good mix will put the listener into the music, not make him figure out where it's coming from.
Digital effects are one of the coolest things about audio mixing. There are all kinds of different effects to try, like:
- EQ (equalization)
- Compression & Limiting
- Reverb & Delay
- Pitch & Time
EQ is probably the most popular effect available, and the most widely used and abused.
An audio signal is made up of different frequencies. You can classify them as low, medium & high. They can [technically] range from 20Hz to 20kHz. What EQ does is modify certain frequencies so you can make it sound better, or more distorted.
There are two main types of EQ's, graphical and parametric. A graphic EQ has 10, 15 or 30 sliders that boost or cut the sound at a pre-programmed frequency. A parametric lets you have more control, specifying which frequencies and how far around them.
Once you learn how to use them, parametric EQ's can be more powerful and easy to use.
Compression is taking the audio signal, and squashing it down to make it quieter. Then, it is usually boosted back up, but the overall sound seems louder after this. Limiting is close, where it says the sound can't go past a set level, no matter how far you turn it up.
Reverbs are fun to use - they can make a audio track sound like it was recorded in another room. A delay can be used to make an echo, or thicken a track up. Try it sometime!
Pitch effects can change the pitch of your music up or down, from a couple cents to several octaves. It usually sounds goofy, but it is fun to try!
Time effects will lengthen or shorten the track, without changing the pitch. The pitch effect is a little more fun, but this one can be useful at times.
Bouncing to disk or tape
After you have all the levels, panning, and effects you want on each of your tracks you are mixing, you can bounce them down to 1 track, (ie., combine then) There is your final mix!
Most software programs will have a function like this (it might be called something other than bounce). If they don't, you can do it manually...
Set all the outputs of your tracks to internal busses. Then make a track to hold the output, and set the input of it to the output of the others. Then hit record!
Another way to do this is plug a 2-track recorder into your outputs, and record that way.
So now you have your final mix, what are you going to do with it? The next step in the recording process is to send it on to the mastering stage.
Hardware and Software mixers
What are the differences?
Probably the biggest thing you'll notice is the feel of them. With a hardware box, you have actual knobs and sliders to move with your hands and fingers.
On software, you need to use a mouse to change the settings, or get a seperate control surface. A control surface is something that provides all the knobs and sliders you need to control the software.
If you think that is a little redundant, you are most likely right. But, you get a lot more control over the project with a software mixer.
I personally use a software mixer without a control surface. It would be nice to have one, but I can't justify the cost of it yet!
If you decide to get a hardware unit, but want all the features of a software program, watch out! The price tag gets pretty expensive there!
Software solutions are usually a lot cheaper, when you compare with hardware with the same specs.
This discussion is also covered in a slightly different sense in the digital recording article.