It’s pretty awesome.
Which is why it’s used so much. Chances are, you probably use it yourself. Doubletracking makes things sound bigger and thicker. Who wouldn’t want that?
Do I need to count the ways?
- Guitars. Especially overdriven guitars. And distorted guitars. And overdriven distorted guitars. The more the merrier. And by ‘merrier’, I mean BRUTALLER. Bonus points for tracking each layer with a slight variation – pickup selector, amp EQ, speaker, mic position, etc.
- Synths. See that ‘unison’ button hidden in the corner? Yeah, that. Try to use enough detuning that it doesn’t just sound like a big silly flanger. But don’t use so much that your sound is an angry swarm of bees. Unless you like that sound. Bonus points for adding a sub oscillator in there somewhere. And distortion. Don’t forget distortion.
- Strings. Solo violin vs string ensemble. Need I say more? Bonus points for actually knowing how to score for a string ensemble. Bedroom ‘producers’ who haven’t had any theory lessons in their life, I’m looking at you.
- Claps. Where would hip hop be without ridiculous unison claps? Doubletracking giant claps is like doubletracking giant baggy shorts. Too much is never enough. Bonus points for running the clap stack through a stereo ring modulator with a square wave carrier. And distortion. Don’t forget distortion.
- Backing vocals. Do it. I usually hate doubletracked lead vocals, but it’s wonderful on backing vocals. Bonus points for compressing each layer individually but EQing them at a group. And distortion.
On the other hand, doubletracking diffuses the sound as well. Doubletracking will make your instrument sound more blurry and indistinct. It reduces clarity. That’s awesome when you want your double tracked instrument to be a supporting part in the background (or middle ground). Giant walls of guitars fill all the frequency gaps left by the vocals and drums. Unison is a great way of softening synth pads and rhythmic comps.
When isn’t it awesome? Probably any time you want the instrument to be front and centre. Of course, there are some stylistic exceptions (have you ever heard a trance lead that wasn’t massively detuned?) but generally doubletracking will push a sound further towards the background, and that’s often not something you’ll want to do for a foreground instrument.