Ok, I'm no expert. But here are some ideas to get the ball rolling....
Parallel processing:-
Copy the vocal onto a 2nd track. EQ the first track for intelligibility. Make it really clear and crisp sounding, but be careful of sibilants.
Then, apply a fat sounding compressor to the 2nd track, with a fairly fast attack and ratio of ~4:1 or 5:1. You want to see gain reduction of anything up to 12dB on the loudest parts, and use the makeup gain to get unity in/out.
Now, blend the 2 tracks to taste. Clarity from the EQ'd track, and body from the compressed track. My preference at the moment is for a phase linear EQ, and a tube-style compressor, but YMMV.
I sometimes run this blend thru a further tube compression stage (TRacks Tube Comp is fine), and with the rest of the arrangement mixed properly, the vocal will sit perfectly top and centre.
Reverbs and delays:-
If you're using a global reverb on the mix, you might find that you want to run the vocal on a separate reverb line, or several separate reverb lines.
Maybe an ambience preset on one reverb line, and a room or hall on a 2nd reverb line. I generally run some gentle tape saturation on at least one of my vocal reverbs.
Sometimes an ambience setting alone will be perfect on the vocal. Sometimes you'll need something with a longer tail as well, or instead.
What type of delay depends on the material. Do you want a single breathy, low level 'echo' a 1/2 note or a bar behind the dry track, a la Dark Side of the Moon? You'll usually need to feed a reverb line with the return from such a delay. The latest Bruno Mars track (its name escapes me) has some great use of this type of delay/reverb combination.
Or slapback? Most delay plugins will have a slapback preset that is easily tweaked to suit your material. Some tape saturation might help on a slapback. But you can get a similar, if more subtle, effect by setting the predelay on your vocal
reverb somewhere around 50-60ms.
After that, 'character' delays are basically whatever you come up with yourself. Just try matching to different beats, 1/4 notes, 1/8ths, 1/16ths, dotted or triplet. Play with the feedback and see what works. If something doesn't work, try something else, or leave it off.
A character delay will usually be much more effective if used sparingly. during a chorus or middle-8, or on background vocals/ad libs.
Double tracking:-
First off, it's usually a good idea to record the 2nd vocal line-by-line, making sure that the timing and pitch are as closely matched as possible. They need to be super-tight. Even then, you will probably end up needing to EQ the 2nd vocal quite drastically to avoid buildups at certain frequencies, and/or kill the sibilants on the 2nd vocal.
You might also find that you don't end up sending both vocals to all of the vocal reverbs and delays. So, one or the other might be the 'driver' of the reverbs and delays.
Another cool thing to try, if the musical key suits the vocalist, is to track the 2nd vocal an octave higher/lower. Beck uses this one a lot. Again, you'll usually need to EQ the 2nd vocal so it sits back a bit.
Time based/modulation effects
Sometimes you can really get a vocal to 'sit' in a mix by adding the teeniest bit of slow flanging. With some modulation plugins, you can set up a flanger with a sawtooth or triangle envelope. Match one cycle to the length of a bar, or 2 bars, and it can be like magic.
Ditto, chorus and phasing. But beware of the above, it's like seasoning on food - too much is too much!
Another way of getting modulation is to use 2 mics on the vocalist. Either side by side, or else one close mic, and another about 2 feet away. You will get phasing when the vocalist moves their head as they're singing, and it can sometimes be very pleasing and useable, but you usually need to get lucky with the take. And it can sound pretty atrocious if it doesn't work.
I believe that the phasing on the vocal for Radiohead's 'High and Dry' was achieved using 2 mics.
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All of the above will work much better if you have a booth, or some sort of isolation for the vocalist. I don't know what kind of setup you have, but the deader the acoustic environment, the easier it will be to sculpt the vocal creatively within your mixes.
Unless of course, you've got a acoustically lively room which makes vocalists sound awesome. In that case, simply put a microphone in front of the vocalist, and disregard all of the other information in this post! All you need to do when mixing a vocal recorded in such a room is set the fader marked 'Vox' to zero
edit:- Sad to say that a modern 'processed' sound will also rely on no small amount of autotune/Melodyne. Get in there and start snapping everything to perfect pitch, straighten out the vocalist's natural vibrato etc., and you'll be well on your way to getting a modern 'glassy' sound.
tafka mintparasol............
'When we live in a culture that really admires money, when that's your primary criterion for who's a good person, who's powerful and who's interesting, you really belittle the human spirit and what it means to be alive. But we tend to do that.'