To mix down audio means to combine several tracks of audio into a single file when doing multi-track recording. The term “render” is more often used these days in many audio software programs. But the terms mean essentially the same thing.
In digital audio workstation (DAW) program, such as Pro Tools or Reaper, you can record several tracks of audio and/or MIDI, and have them play back together. Multiple tracks can be recorded simultaneously or one at a time. That last option is very handy if you are a solo musician. You can play a guitar on track one, another guitar on track 2, sing on track 3, sing harmony 1 on track 4, then sing harmony 2 on track 5, and so on until you’re done. You can listen to your previous track(s) as you record each subsequent one. It’s very cool. But I digress.
Once you have your 5 (or however many) tracks all recorded, and they play back nicely together with each track at just the right volume (because you adjusted the individual volumes of each track – a process called mixing), you’re ready to save your masterpiece and share it with the world. But wait. In what format does the world expect to see my masterpiece audio? Well if you are creating a CD, you probably want a wav file. If you’re going to be sharing the audio on the web, you’ll probably want an mp3 file. The point is, you’re going to end up with just one file. At the moment you actually have 5 (or however many tracks) separate audio files in your DAW project/session.
Your DAW will have an option called either “mix down” or “render” (more common these days). What this option does is combines the output of all your tracks, at their current volume relative to the other tracks, into one audio output. It’s like putting lots of things (like 5 audio files) into a funnel, and having only thing (wav or mp3 file) that is a mixture of the 5 sources come out the small end. See the picture on the right, which pretty much sums up (no pun intended…OK, pun intended) mixing down.
The term to mix down comes from the idea that you have many bits of audio spread across many different tracks when recording, but ultimately you’ll need to combine it all into a format that a consumer can use. Even in the old days when we were recording on very wide strips of magnetic tape, a mix-down session would happen at some point, where all that audio would be transferred onto a 2-track tape (one “track” for the left channel and one for the right channel for stereo), which was much much thinner and could be played back on some consumer machines (you did own a reel-to-reel machine back in the day didn’t you?), but more importantly, on the machines at mastering houses (another article), where the audio would be transferred to records or cassette tapes.
The phrase “mix down” is actually kind of phasing out since so much stuff is done on computer these days. I’ve mentioned a few times that the term “render” is often used these days to mean the same thing as “mix down.” I believe that this is at least partially because rendering is the term used when doing the same basic process in video production. And since there is now a lot of cross-over between video and audio in the software of both worlds, terminology is becoming more standard. Just know that if you see the term “render,” it means the same thing described in this article as “mixing down.”
You can learn how to mix down your own audio, as well as tons of other awesome audio tips and tricks, in Reaper software in the Newbies Guide To Audio Recording Awesomeness 2: Pro Recording With Reaper tutorial course. Now go forth and mix down or render your masterpiece.