PreSonus StudioLive AI Series - Manual (Page 57)

4 Universal Control-AI and VSL-AI
4.9 Smaart System Check Wizards
StudioLive ™ AI Software Library
Reference Manual
53
4.9.7 Using the Trace: Spotting the Trend
As discussed in the previous section, many factors can affect the response
of a sound system: the room, system configuration, electronics, wiring, and
more. Part of understanding what you see is knowing what you should
not be seeing—or at least having a basic idea of what to expect. After
all, you are trying to sculpt the EQ curve of the system into something
that compliments that sound system’s frequency response.
For example, a small system without a subwoofer can’t reproduce much energy
below 50 Hz. In fact, this frequency cutoff could be even higher, depending
on the size of the speaker, its factory tuning, porting, etc. This means that
if you are analyzing a system that is comprised of two 2-way, 12” powered
speakers, you should expect your frequency-response trace to drop off
around 50 Hz or so (depending on the frequency response of your speakers).
Because of this, boosting low frequencies in this type of system wouldn’t
achieve much and may introduce more problems than it would solve.
Power User Tip: A subwoofer can significantly change the frequency response of a full-
range system. A 3-way system with a subwoofer will be 6 to 18 dB hotter below 80 to 100
Hz than a 3-way system without a subwoofer. Keep this in mind when viewing your trace.
Different types of live performances make different demands of a PA system.
A classical concert has very different needs from a rock concert. Just as you
wouldn’t mix an evening of Bach quartets the same as an evening of thrash metal,
you don’t want to tune your PA system the same for both types of events.
A classical concert doesn’t need an exaggerate subwoofer output. The audience
and performer expect and want a natural reproduction of the music. In contrast,
systems that are tuned for a rock show will use subwoofers essentially as an
effect. This is how they achieve those pummeling kick and toms and huge
bass guitar sound: the system is pre-tuned with more bass response.
In other words, you can stack the deck to be assured of a big FOH mix win. In system
alignment, this deck stacking is called “trends.” Every genre and performance type
requires a different type of trend. The sole objective of a system EQ is to smooth
out the sound system by creating a uniform slope that the system follows. This
will give your system a more uniform sound and performance, as well as better
clarity, because your system has been pre-EQ’d to meet the needs of the concert.
Below are some examples of trends for various applications:
Music Concert
Subs
2 to 4 kHz
Rock Concert
Subs
Extended LF
2 to 4 kHz