Sometimes I find that doubling a vocal is a powerful way of getting the point across. Doubling a vocal can do things that no reverb or delay could ever hope for if executed properly in the right song and context. However, sometimes vocal doubling doesn't work out exactly like you think it would. In these cases, there quite a few options we have to get that “doubled” vocal sound we are looking for.
It's important to note that the effectiveness of vocal doubling varies tremendously from singer to singer. Some vocalists will sing a line differently every single time. This can make doubling hard. Some vocalists are so precise that you can barely tell if they have even doubled at all. It's up to you to work with or around your singer to get the doubled sound to work (if that's what you are going for).
Many times I will spend hours tweaking the extra layers to get them to fit with the lead vocal. I'll automate the living crap out of those tracks to give me exactly what I want. If they jump out in weird places, I'll turn them down so they don't jump out anymore. If the high end is distracting in the vocals, I'll quickly yank it out. I find myself rolling out everything above 4Khz quite often when working with layers (except in the lead vocal).
Here are a few examples of doubling tricks.
A straight double is a track that is set at the same volume as the lead vocal. Essentially you have two tracks giving 50% a piece. This can work well for some singers, but the takes need to be very similar. Volume automation can help, but is often tough to get right because it can make drastic differences in tone. You will here timing differences in the highs with this method quite a bit.
It is the most intense of doubled effects. Essentially the wet/dry ratio is 50/50 from the lead vocal to the double. This is where I start when doubling.
Straight Double With Crazy EQ
Sometimes there will be frequency buildups that can sound weird with doubling when both tracks are the same level. Sometimes it's necessary to use drastic EQ settings to get what you are looking for. Don't be afraid to boost or cut any frequency to get what you are looking for.
Double Down 6 Decibals
Sometimes you have to turn down the double because it's simply too much. I find that if a straight double is too much, turning the doubled track down 6dB can make the doubling effect much more subtle. You can get away with inconsistencies in the tracks much more with the double down. You don't have to use 6dB. You may want to yank it down only 3dB or you may like it -20dB.
Just make sure that when you set the level of the double that you can still hear it's effect. It's easy to fall in love with a dry vocal, but if you force yourself to leave the doubled sound on there, you will adapt to it most of the time and end up loving it.
Triple Panned Wide
Sometimes I like to record on great lead vocal track which we work very very hard on and then I like to slap 2 additional vocal tracks on there. I'm usually not concerned about pitch or even timing too much. I just want 2 new tracks. I'll take each of these and pan them anywhere from 100% wide to 30%. Then, I'll knock the high end off and compress them extremely hard. I'll play with the level enough until I get what I'm looking for. This type of sound is more of a stereo vocal and a straight double.
In many songs, I like this effect. Remember that you will really have to automate the layered tracks to make it work.
Double Reverb Send
Another trick that I've found to be amazing is tracking two vocals, keeping the lead vocal dry, and then only sending the doubled vocal to a reverb. This can be amazing for epic 80s ballads using tons of reverb. Something magical happens when you use a doubled track exclusively for reverb and nothing else. It's hard to explain. Try it!
16 Layers of Vocals
I've heard stories of Avril Lavign's first record using this trick a lot. They say it's the modern vocal sound. Basically, you just track vocals over and over and over. You pan them from 100% wide to center usually keeping the hardest panned tracks the lowest in level. Then you EQ them all differently.
I've tried this a few times and couldn't make it work for me. However, the concept still makes sense.
I've heard that Def Leopard employed the 16 layers trick when they were doing their “football vocals” that sound like a large crowd yelling at a football game or whatever.
A really creepy effect is to double whispers. That's right, have the singer whisper the entire verse or whatever. Forget singing. Then have him/her do it again. You can do some amazing things with this trick. You can add lots of air to track by creatively using layered whispering, you can add long reverbs to just the whispers to basically extent the high end.
Actually, I'd love to try a long reverse reverb on whispers. That may sound really creepy for a song that calls for this sort of thing.
Straight Double Panned Wide With Delay
Another cool trick is to use a straight double but then using a stereo delay with 2 bounces set to the lowest setting. You want one bounce panned hard left and one bounce panned hard right. Basically, this is a stereo simulator. (You may need to knock some top end off of this one). Send your doubled track entirely to that. It can make your vocals sound really huge without lots of layering.
Sometimes distorting the doubled track can add a really cool texture if you can find the level which it belongs. I don't use this one that often, but it has came in handy over the years. It can add a sense of air to the track if you do it correctly.
Single Track Copied and Split Into Multibands
Of course, you don't have to double to apply some of these tricks. Recording software makes it easy to make copies of a track. Well keep your lead vocal put and then make 3 copies of it. On one track, label it “vocal-hi-end” and roll off everything under 4Khz. Label one mid and label one low end and set Eq appropriately. Then smash the living crap out of each one with compression. Blend them to taste. Usually the vocal-hi-end is useful for adding air, but experiment. There are no rules.