User manual

193
Audio effects
Dithering
Dithering is a method for controlling the noise produced
by quantization errors in digital recordings. The theory be-
hind this is that during low level passages, only a few bits
are used to represent the signal, which leads to quantiza
-
tion errors and hence distortion.
For example, when “truncating bits”, as a result of moving
from 24 to 16 bit resolution, quantization errors are added
to an otherwise immaculate recording. By adding a spe-
cial kind of noise at an extremely low level, the effect of
these errors is minimized. The added noise could be per
-
ceived as a very low-level hiss under exacting listening
conditions. However, this is hardly noticeable and much
preferred to the distortion that otherwise occurs.
When should I use dithering?
• Consider dithering when you mix down to a lower reso-
lution, either in realtime (during playback) or with the Ex-
port Audio Mixdown function.
A typical example is when you mix down a project to a 16-bit stereo au-
dio file for audio CD burning.
What is a “lower resolution” then? Well, Cubase uses 32-
bit float resolution internally, which means that all integer
resolutions (16 bit, 24 bit, etc.) are lower. The negative ef
-
fects of truncation (no dithering) are most noticeable when
mixing down to 8 bit, 16 bit and 20 bit format; whether to
dither when mixing down to 24 bits is a matter of taste.
Applying dithering
1. Open the VST Output Channel Settings window by
clicking the “e” button for the Output channel in the Mixer.
You can also display the Inserts section in the extended Mixer pane.
2. Open the Inserts pop-up menu for slot 7 or 8.
The two last Insert effect slots (for all channels) are post-fader, which is
crucial for a dithering plug-in. The reason is that any master gain change
applied after dithering would bring the signal back to the internal 32 bit
float domain, rendering the dithering settings useless.
3. Select the included UV22HR plug-in from the pop-up
menu.
The included dithering plug-ins and their parameters are described in the
separate PDF document “Plug-in Reference”. If you have installed an
-
other dithering plug-in that you prefer, you can of course select this in-
stead.
4. Make sure that the plug-in is set to dither to the cor-
rect resolution.
This would be the resolution of your audio hardware (on playback) or the
desired resolution for the mixdown file you want to create (as set in the
Export Audio Mixdown dialog, see the chapter
“Export Audio Mixdown”
on page 484).
5. Use the other parameters in the control panel to set up
the dithering to your liking.
Using group channels for insert effects
Like all other channels, group channels can have up to
eight insert effects. This is useful if you have several audio
tracks that you want to process through the same effect
(e.
g. different vocal tracks that you want to be processed
by the same compressor).
Another special use for group channels and effects is the
following:
If you have a mono audio track and want to process this
through a stereo insert effect (e.
g. a stereo chorus or an
auto panner device), you cannot just insert the effect as
usual. This is because the audio track is in mono – the
output of the insert effect will be in mono as well, and the
stereo information from the effect will be lost.
One solution is to route a send from the mono track to a
stereo FX channel track, set the send to pre-fader mode
and lower the fader completely for the mono audio track.
However, this makes mixing the track cumbersome, since
you cannot use the fader.
Here is another solution:
1. Create a group channel track in stereo and route it to
the desired output bus.
2. Add the desired effect to the group channel as an in-
sert effect.
3. Route the mono audio track to the group channel.
Now the signal from the mono audio track is sent directly
to the group, where it passes through the insert effect, in
stereo.