It’s been a few weeks
that I have been doing the Coursera Introduction to Music Production course and
I have really had an opportunity to learn what it takes to successfully produce
music. It has opened my eyes to so many
things that I just had no clue existed.
I would recommend this course to anyone interested in music or sound at
all.
Algorithmic and Convolution Reverb
I’m going to go over
reverb and then compare Algorithmic and Convolution reverb plugins with this
entry.
Reverb:
Reverb is an
electronically produced echo effect in recorded music. In other words reverb is a delay plugin that
can be added to your tracks to simulate a type of echo to give the listener a
feeling of space and dimension. When
sound is produced, let’s say a hand clap in a room, the sound wave bounces off
the walls and then back to our ears. The
original sound and the sound bounced off the wall meet our ears at slightly
different times and cause an echo. This
echo helps us interpret the space the sound was made in.
When we record music
we try get the cleanest sound possible, but when we are mixing we may want to
give the listener an image of the sound being recorded somewhere else, for
example a large hall or theatre. We can
use a reverb plugin that will give the track an artificial environment
effect. This can really polish the final
mix.
Algorithmic Reverb:
Algorithmic reverb is
an effect that can be added to the tracks during mixing. This type of reverb uses mathematical calculations
to create reverb. It is a computer
created process and allows the producer to highly customize the synthesized reverb
sound. Some of the parameters you
control are reverb time, room size and room shape as well as stereo
controls. We can use a Dry and Wet
control to focus the tracks and to move certain instruments or vocals into
focus or blend them back into more of an effect. The more Wet control in use the more in the
track moves out of focus.
Some Algorithmic
Reverb plugins are separated into an Early reflection and a Reverb
section. If the balance is focused completely
to the early reflection side the sound is similar to a slap back delay. All Algorithmic Reverb plugins have a
variation of the following parameters.
Parameters:
Low Cut - Adjusts the low cutoff frequency. Use this parameter to
remove low frequencies from the input signal before reverb is added. For
example, when adding reverb to a drum track, you might want to remove some of
the 'rumble' from the bass drum by attenuating the bass frequencies. Setting
this parameter to the minimum value will bypass the Low Cut filter, displaying
OFF in the value field.
High Cut - Similar to Low Cut.
Adjusts the high cutoff frequency. Use to remove high frequencies from the
input signal.
Predelay - Controls the delay time between the direct input signal and
the first reverb reflection. Set to lower values for small rooms, and increase
relative to the room size. Predelay creates a slap-back echo effect that can
add atmosphere and muffle the signal, so use it wisely.
Room Size - Sets the size of the virtual room where the reverb is
created. Adjust according to decay time. The Room Size should be adjusted
according to the decay time. Small rooms sound best with a shorter decay times,
while large rooms are suited to longer decay times.
Diffusion - Controls the density of the reflections bouncing off the
walls of the virtual room. A low diffusion setting makes the reflections sound
more distinct, like closely spaced echoes. A high diffusion setting creates
reflections so close they sound more like noise, in which echoes are
indistinguishable.
Color - Use to adjust the decay time of the bass frequencies of the signal. Five
settings are available: Brighter, Bright, Flat, Warm and Warmer. This parameter
allows you to change the overall perceived mood, or 'sound' of the virtual
room. A bright room has a low bass response, while a warm room has a high bass
response. In a flat room, the response of the bass is equal to the general
frequency response.
Decay - Controls the decay time of the reverb, i.e. the time it takes for the
signal to decay to -60dB (1/1000 of the maximum amplitude). Use low decay times
for small rooms or boxes, and long decay times for large rooms, halls or
churches. You should also make sure that the Room Size parameter has an
appropriate value.
High Damping - Allows you to adjust damping of the high
frequencies in the reverb signal over time. Damping refers to the high
frequencies being attenuated and dying out. This causes the sound to become
gradually warmer and more muffled, as if it is being absorbed in the room.
Setting this parameter to the maximum value will bypass the High Damping,
displaying OFF in the value field.
Dry - Sets the relative dry output level.
Reverb - Sets the relative
reverb (wet) signal level.
Convolution Reverb:
Convolution reverb is
a plugin used more like a sampler since it has samples of actual spaces and
environments that are then added to the track to simulate the recording in that
space. This sample is also known as an
impulse response. This plugin can have
samples from places the producer may not have access to like a famous concert
hall or canyon.
Convolution reverb
plugins do not allow for as many customizations as the Algorithmic reverb
plugin so this can limit the producer’s opportunity to truly customize the
reverb. Also this type plugin will
require trial and error to find just the right impulse response for the track.
Most Convolution reverb
plugins will have a variation of the following parameters.
Parameters:
Dry - Adjusts the level of the dry signal (0 to 100%).
Input stereo separation - Turn left to maximize stereo separation of the
input or right to create a mono input.
Wet - Adjusts the level of the wet signal (reverb / convolution) sound (0 to
100%).
Normalize - Loudness normalization. This is useful to maintain a
consistency across impulses as there can be dramatic differences in gain
between them.
Wet stereo separation - Enhance or reduce the stereo effect in the wet
output.
Delay - Adds a delay to the first reflection from the impulse. NOTE: Fruity Convolver
puts any set or detected delays to good use, using the time afforded by the
delay lower CPU load. Many reverb impulses have a period of silence at the
start, the time taken for the sound to reflect off the closest surface to the
microphone/s. Fruity Convolver will detect these delays and will use the extra
time to reduce its CPU load also.
Self-conv - The impulse is convolved with itself before being convolved
with the input. This creates a similar effect to putting a reverb on the
impulse.
Stretch - Uses high quality resampling to change the length & pitch of the
impulse. NOTE: This is not timestretching so the frequency of the impulse
response is shifted lower with stretching and higher with time-compression. It
usually sounds right, unlike time-stretching on the impulse with constant pitch
from the editor functions that often results in phasing artifacts.
Eq - Balance between the Equalized and Normal impulse response.
KB Input - Select to enable keyboard shortcuts in the impulse & EQ editors.
Updating - Animates while the plugin is processing changes to
settings. There may be a short period of silence when the convolution algorithm
updates. Note: Don't touch the delay, stretch, self convolve or eq controls if
an interruption to the sound will be an issue (live performance for example).
Load Impulse Click the Browse
impulses button (shown green above) and drag Impulse files from the Browser
and drop on the Editor Window.
Left-clicking - Shows the location of the currently loaded
impulse response.
Right-clicking - Shows FL Studio's default impulse response
folder.
Shift + Up / Down Arrow keys - Will step up/down the Browser list and will
load the impulse response into the most recently focused Fruity Convolver.
Alternatively click the disk icon and use the Windows file browser to
locate your own impulse responses.
Envelopes - Several standard envelope controls are accessible along the
bottom of the window that act on the Impulse sound. From left to right -
Pan To edit the Pan envelope.
Volume To edit the Volume envelope.
Stereo Separation To edit the Stereo Separation envelope.
All-purpose envelope Can be assigned to playback velocity/direction
and various other functions.
Editing envelopes - After selecting the desired envelope type,
Right-click in the 'Impulse Editor Window' to add points, and Left-click to
move points and tension markers. Right-click points to open a context menu that
will allow you to delete points or change the curve type.
Trigger impulse (spark icon) - Click this icon to create a
'click' impulse to create impulses from plugin effects .
Reflection
There are many other
types of plugins that can be used when mixing but for reverb most producers
will use either a form of Algorithmic or Convolution reverb. They are both extremely helpful in focusing
the listener to the tracks that you want them to hear and they really help to
polish the project. The Algorithmic like
a synthesizer gives the producer more customization options and the Convolution
allows the producer to make the listener believe the recordings were done in
real spaces through samples. Both
methods give the listener a wonderful experience if used correctly.
This lesson allowed me
to focus on new areas of sound. I have
heard the effects before but did not really know what they were or how to tell
them apart. I hope this was helpful for
you and you will begin to explore the use of reverb.
