A Brief Tutorial On Dynamics Processing; Common Questions Regarding Dynamics Processing; Types Of Dynamic Processing - PRESONUS StudioLive 16.0.2 Owner's Manual

8 Tutorials
8.2

A Brief Tutorial on Dynamics Processing

8.2 A Brief Tutorial on Dynamics Processing
The heart of the StudioLive is the Fat Channel dynamics section. What follows
is an excerpt from brief tutorial on dynamics processing written by PreSonus
president and founder Jim Odom. It is included to help you get the most out
of your StudioLive. This tutorial will take you through the basics of dynamics
processing and will explain the various types of dynamics processors.
8.2.1

Common Questions Regarding Dynamics Processing

What is dynamic range?
Dynamic range can be defined as the ratio between the loudest possible audio
level and the lowest possible level. For example, if a processor states that the
maximum input level before distortion is +24 dBu, and the output noise floor
is -92 dBu, then the processor has a total dynamic range of 24 + 92 = 116 dB.
The average dynamic range of an orchestral performance can range from
-50 dBu to +10 dBu, on average. This equates to a 60 dB dynamic range.
Although 60 dB may not appear to be a large dynamic range, do the math,
and you'll discover that +10 dBu is 1,000 times louder than -50 dBu!
Rock music, on the other hand, has a much smaller dynamic range:
typically -10 dBu to +10 dBu, or 20 dB. This makes mixing the various
signals of a rock performance together a much more tedious task.
Why do we need compression?
Consider the previous discussion: You are mixing a rock performance with an
average dynamic range of 20 dB. You wish to add an uncompressed vocal to the
mix. The average dynamic range of an uncompressed vocal is around 40 dB. In
other words, a vocal performance can go from -30 dBu to +10 dBu. The passages
that are +10 dBu and higher will be heard over the mix. However, the passages
that are at -30 dBu and below will never be heard over the roar of the rest of the
mix. A compressor can be used in this situation to reduce (compress) the dynamic
range of the vocal to around 10 dB. The vocal can now be placed at around +5
dBu. At this level, the dynamic range of the vocal is from 0 dBu to +10 dBu. The
lower level phrases will now be well above the lower level of the mix, and louder
phrases will not overpower the mix, allowing the vocal to "sit in the track. "
The same points can be made about any instrument in the mix. Each instrument
has its place, and a good compressor can assist the engineer in the overall blend.
Does every instrument need compression?
This question may lead many folks to say "absolutely not, overcompression is
horrible. " That statement can be qualified by defining overcompression. The term
itself must have been derived from the fact that you can hear the compressor
working. A well-designed and properly adjusted compressor should not be audible!
Therefore, the overcompressed sound is likely to be an improper adjustment on
a particular instrument—unless, of course, it is done intentionally for effect.
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PreSonus StudioLive ™ 16.0.2 Owner's Manual
Why do the best consoles in the world put compressors on every channel?
The answer is simply that most instruments need some form of
compression, often very subtle, to be properly heard in a mix.
Why do we need noise gates?
Consider the compressed vocal example discussed earlier; you now have a
20 dB dynamic range for the vocal channel. Problems arise when noise or
instruments (air conditioner, loud drummer, etc.) in the background of the
vocal mic become more audible after the lower end of the dynamic range is
raised. You might attempt to mute the vocal between phrases in an attempt to
remove the unwanted sounds; however, this would probably end disastrously.
A better method is to use a noise gate. The noise-gate threshold could be
set at the bottom of the dynamic range of the vocal, say -10 dBu, such that
the gate would shut out the unwanted signals between the phrases.
If you have ever mixed live sound, you know the problems cymbals can create
by bleeding through the tom mics. As soon as you add some highs to get some
snap out of the tom, the cymbals come crashing through, placing the horn drivers
into a small orbit. Gating those tom mics so that the cymbals no longer ring
through them will give you an enormous boost in cleaning up the overall mix.
Dynamics processing is the process of altering the dynamic range of a signal, thereby
enhancing the ability of a live sound system or recording device to handle the signal
without distortion or noise and aiding in placing the signal in the overall mix.
8.2.2

Types of Dynamic Processing

Compression/Limiting
Punch, apparent loudness, presence—these are just three of the many
terms used to describe the effects of compression/limiting.
Compression and limiting are forms of dynamic-range (gain) control. Audio
signals have very wide peak-to-average signal-level ratios (sometimes
referred to as dynamic range, which is the difference between the loudest
level and the softest level). The peak signal can cause overload in the audio-
recording or sound-reinforcement chain, resulting in signal distortion.
A compressor/limiter is a type of amplifier in which gain is dependent on the
signal level passing through it. You can set the maximum level a compressor/
limiter allows to pass through, thereby causing automatic gain reduction
above some predetermined signal level, or threshold. Compression refers,
basically, to the ability to reduce, by a fixed ratio, the amount by which a
signal's output level can increase relative to the input level. It is useful for
lowering the dynamic range of an instrument or vocal, making it easier to
record without distorting the recorder. It also assists in the mixing process by
reducing the amount of level changes needed for a particular instrument.
Take, for example, a vocalist who moves around in front of the microphone while
performing, making the output level vary up and down unnaturally. A compressor
can be applied to the signal to help correct this recording problem by reducing
the louder passages enough to be compatible with the overall performance.
Tutorials 8
A Brief Tutorial on Dynamics Processing 8.2
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