PreSonus DigiMax 96k - Manual (Page 15)

TECHNICAL INFORMATION
13 | PreSonus 2007
3.3 A BRIEF TUTORIAL ON DYANAMICS PROCESSING
The DigiMax 96k features a dual domain limiter with a variable threshold on each of its eight channels. This
section is an excerpt from brief tutorial on dynamics processing written by PreSonus President and Chief
Technical Officer, Jim Odom. It is included to help you get the most out of your DigiMax 96k. This tutorial will
take you through the basics of dynamics processing as well as explain the various types of dynamics processors,
including limiters.
3.3.1 Common Questions Regarding Dynamics
What is dynamic range?
Dynamic range can be defined as the distance between the loudest possible level to the lowest possible level.
For example, if a processor states that the maximum input level before distortion is +24dBu and the output
noise floor is -92dBu, then the processor has a total dynamic range of 24 + 92 = 116dB. The average
dynamic range of an orchestral performance can range from -50dBu to +10dBu on average. This equates to
a 60dB dynamic range. 60dB may not appear to be a large dynamic range but do the math and you’ll
discover that +10dBu is 1000 times louder than -50dBu! Rock music on the other hand has a much smaller
dynamic range, typically -10dBu to +10dBu, or 20dB. 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
20dB. You wish to add an un-compressed vocal to the mix. The average dynamic range of an uncompressed
vocal is around 40dB. In other words a vocal performance can go from -30dBu to +10dBu. The passages
that are +10dBu and higher will be heard over the mix, no problem. However, the passages that are at
-30dBu 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 10dB. The vocal can now be placed
at around +5dBu. At this level, the dynamic range of the vocal is from 0dBu to +10dBu. 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 discussion 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 of each instrument.
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, ‘overcompression’ 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.
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, oftentimes very subtle, to be properly heard in a mix.