There are many ways to process the files to get a choir effect. Doubling, chorusing, pitch shifting, delays, and using harmonizers are just a few common techniques. I typically will duplicate the original file several times and experiment with a variety of processing till I get what I want, then render it. I've made a large choir from 1 person singing a couple of different parts, then processed these parts in a various ways.

drbam

"If you want it to sound like a choir you have to shift each layers few milisec."

I disagree. Although it may seem like it just might get louder if you sing the same part twice, it is NEVER the same twice. There are enough differences between timbre and nuances that the part is not identical. Recording engineers use this technique all the time, to make a singers voice sound fuller. (ie they have the singer sing the same part twice and record it onto 2 seperate tracks). This is what is called double tracking. You never shift the parts, because this will make the performance sound sloppy. You're looking for fuller sound, not a sloppy performance. You can try to achieve this with 4 people to make a choir voice. I've actually done this and it turned out quite good for what I was trying to achieve. I had the four singers sing their part at their particular pitch, and then I had them double that track 2 additional times. So in other words 12 tracks of 4 different parts. In the mix you can pan the parts in the same location, or hard left/right which will bring them to the center but make it sound wider. Then add a little chorus and some large church reverb and you have a choir.

thanks, those are all good pieces of info.
Carson

If you have the time, get your four singers to also do a group take or two. Gather them around a stereo pair of mics and get them to sing at the same time. I find this better than individual mics because for the most part singers will control their volume to make it work. Make sure to get individual takes as well for proper control of the end sound.
Steve S.

Rednroll:
I think you missed Shmuel's point. If all you have is one take of four singers, and you want to make them sound like (more like) a choir, you have to shift the layers a bit - I think that is what Shmuel was trying to say.

If you have the luxury of making multiple takes, then, sure, that will produce (usually) an even more realisting effect (I'm assuming that subsequent takes would be made using the initial take as a gude for ensemble purposes.

Using the multiple take technique, you could literally make a choir out of just one voice - assuming the human behind that voice possessed adequate vocal/musical skills.

When I have to do the "layer shifting" stuff, I'm careful to shift subsequent layers a bit in both directions from the initial layer to avoid that sloppy sound to which you allude.

I've also made mono recordings sound stereophonic (or multi-channel) using the same technique. As long as you don't get carried away with the degree of shifting, and you average it in both directions (moving one layer slightly ahead of the initial, and another slightly behind), you can get that choir effect without making the performance sound sloppy.

After all, it's the inherent "sloppiness" inherent in an ensemble of 100 singers that make them sound like a choir and not just a voice amplified by a factor of 100 (ok, sure, issues such as vocal timbre add to the choral effect in a group as well, I agree).

Just thinking out loud (with one voice on one track).

Caruso

There are some good suggestions.

Double tracking is a good way, but you can expand on this - pan your double tracks, and record some in a different way - I.E. distant mic'd in the room, then mix these in with the other tracks. Try and capture some real ambience as this is what a choir really sounds like.

You could also process copies of some of the tracks with acoustic mirror to generate a similar effect.

I've done some cool stuff with this plugin...

http://www.cloneensemble.com/

HTH.

Ed.