The nice thing about Final Scratch is that I can "lock" the pitch, so if I'm playing one record at -4% and another at +6% they'll still match. With vinyl I had to account for the pitch difference, so it took much more effort to work out harmonic mixes.
Here's the basic process that I follow with my digital collection:
1. Whenever I buy a new MP3 I'll play it back and try to identify the key using a softsynth. You have to have a bit of an ear for this. Basically, you're looking for the root note. Typically this is the note that the bass line revolves around. I'd say something about being able to differentiate between major and minor keys, but it hasn't come up with any of the electronic music I've bought (it's all minor!)
2. Once I've identified the key I'll stick it in a few different places:
- At the start of the filename (i.e. A#_song.mp3). This allows me to find complimentary tracks without having to even load them up.
- In the ID3/4 comment tags
- At the end of the song title, i.e. Title (A#)
When mixing, I keep a spreadsheet open in the background with all the complimentary keys:
As you can see I've highlighted a few cells in yellow. This is because it can be annoying to move to and from sharp/flat keys, so I've highlighted where these transitions can happen. Lately I've been pitch shifting some songs to create more possibilities (more on this in another post)
An alternative to my technique would be to use the Camelot wheel, and index everything based on key code. This way, when sorted the complimentary tracks would appear side by side. Frankly I don't mind working with the keys though, because they're more meaningful from a musical perspective. It just means a bit more scrolling.
