Synthesizing a stereo image for a mono mix
Let's say you have a mono recording of a band (or a party, or anything
that's a full mix), and you want to give it a nice stereo image.
There are some easy ways to do this, and it's a very good idea. Not
only does it sound more natural (unlike mono, where the sound seems
to be coming from inside your head), but it can also make it much
easier to distinguish the different instruments, or hear different
speakers more clearly!
Whether you want to do this depends on how important it is to be
"pure" versus just creating a nice general impression and making
it easy to distinguish different instruments. (A well-crafted stereo
image, even a fake one, will REALLY help the listener distinguish
different instruments.) However, it introduces artifacts that a
purist may not care for.
Using stereo reverb
The simplest method, and fairly effective but not necessarily
helping separate the instruments much, is to use a little stereo
reverb. Here's how:
That's all there is to that!
- In the track properties, click "expand mono track to stereo".
Save the song and reload it (do this whenever you change this
setting, if you've already plugged in any FX.)
- Plug in "n-Track Reverb" and use the "Ambience 2" setting.
Adjust the wet level to taste. Minimize the tails, if you
want, by increasing "damping".
Using "mid-side pitch shift doubling"
This is my favorite technique. It's a little complicated but has
some very nice qualities. It's particularly good at separating the
instruments in your mind. Also, it cancels out completely in mono,
so purists can always get what they want by pushing the "mono" button
on their stereo.
Unfortunately, it doesn't work quite as well in digital as it did back
in the bad old days of bucket-brigade delays. Those old BBD devices
preserved phase information, whereas modern FFT methods don't, and
phase information is really the critical component. Regardless, it's
still well worth a try and usually sounds pretty good. You just don't
get the clarity of separation -- or maybe my ears just aren't as good ...
That's about all there is to it. Sounds more complex than it really is; once
you do it you'll find it's very easy. Be sure to readjust the 2nd track's
fader after fussing with your other plugins, and vice versa.
- Duplicate the mono track.
- On the new track, use "Expand mono track to stereo".
- Go to the n-Track EQ dialog (double-click on the faint little
graph near the track eq knobs), and click "phase shift" for one
side only (e.g., R but not L).
- Plug in "n-Track Pitch Shift" on the new track.
Set the "accuracy" as high as your CPU can stand it.
Set "wet" level to 0dB (that is, 100%), and "dry" to -inf (0%).
- Set the pitch shift to a very small amount -- the least you
can get and see a difference in the numbers on the display.
(I think it's 0.1% or maybe 1%.)
- If you want to use any other plugins, you'll need to use a group.
For each track, assign the "Output to" to "Group 1" (or any unused
group). Put all your plugins on this group (except the pitch shift,
of course). (You'll find the group in the mixer view.) Delete any
plugins you might have put on the original track. This makes it so
that all plugins are applied to both tracks equally.
- Drag the new track's fader to zero. Pan both tracks dead center.
While listening, push the fader up until you can clearly hear a nice
stereo image. (Then, following the "less is more" general principle,
back it off a bit.)