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6
Digital Effects | Master Control
6.3
Graphic Equalizer
StudioLive™ 16.0.2 USB
Owner’s Manual
Graphic EQs are generally used to fine-tune the overall mix to create the aesthetic
that you are trying to achieve. For example, if you are mixing a rock band, you
may want to boost some of the low end to get more pummeling kick and
toms. In general, you do not want to make drastic amplitude adjustments to
any particular frequency band. Making smaller, incremental adjustments over
a wider spectrum will round out your final mix for a more polished sound.
To assist you with these adjustments, here is an overview of
which frequencies affect different sound characteristics:
Sub-Bass (16 Hz to 60 Hz). The lowest of these bass frequencies are felt, rather
than heard, as with freeway rumbling or an earthquake. These frequencies give
your mix a sense of power, even when they only occur occasionally. However,
overemphasizing frequencies in this range will result in a muddy mix.
Bass (60 Hz to 250 Hz). Because this range contains the fundamental notes
of the rhythm section, any EQ changes will affect the balance of your mix,
making it fat or thin. Too much emphasis will make for a boomy mix.
Low Mids (250 Hz to 2 kHz). In general, you will want to emphasize the lower
portion of this range and de-emphasize the upper portion. Boosting the range
from 250 Hz to 500 Hz will accent ambience in the studio and will add clarity to
bass and lower frequency instruments. The range between 500 Hz and 2 kHz
can make midrange instruments (guitar, snare, saxophone, etc.) “honky,” and too
much boost between 1 kHz and 2 kHz can make your mix sound thin or “tinny.”
High Mids (2 kHz to 4 kHz). The attack portion of percussive
and rhythm instruments occurs in this range. High mids are also
responsible for the projection of midrange instruments.
Presence (4 kHz to 6 kHz). This frequency range is partly responsible
for the clarity of a mix and provides a measure of control over the
perception of distance. If you boost this frequency range, the mix will
be perceived as closer to the listener. Attenuating around 5 kHz will
make the mix sound further away but also more transparent.
Brilliance (6 kHz to 16 kHz). While this range controls the
brilliance and clarity of your mix, boosting it too much can cause
some clipping so keep an eye on your main meter.
The StudioLive graphic EQ features an innovative design that sets it
apart from traditional graphic EQs. Traditionally, a 31-band graphic EQ
uses 31 second-order shelving filters with fixed frequencies in order to
simulate a curve set by the user via 31 front-panel sliders. A well-designed
graphic EQ creates an output frequency response that corresponds as
closely as possible to the curve displayed graphically by the sliders.
In an analog EQ, this is achieved by carefully choosing the bandwidth of the filter
and deciding how, or if, it varies with the gain and how the filters are summed
or cascaded. In general, narrower bandwidth signifies a more precise EQ. But in
traditional graphic EQ designs, the center frequency of each band is fixed.
PreSonus took a different approach with the StudioLive. The StudioLive graphic
EQ is a pool of shelving filters from which coefficients like cutoff frequency,
bandwidth, and gain are extracted through a process of curve-fitting. The curve
entered by the user is first oversampled. The system then works with an internal
curve made up of 128 bands to find coefficients for the first shelving filter
that, when subtracted from the user’s curve, will produce the flattest possible
response: 0 dB. The resulting response is then used to find coefficients for the
second shelving filter through the same optimization process. Coefficients
for all available shelving filters are found through a recursive process.
Unlike conventional designs, the frequency and bandwidth of the “bands”
depends on the curve entered by the user. This allows for much tighter matching
of that curve. Because of this innovative design, the accuracy of the StudioLive
EQ might feel “wrong” at first. The curve fitting process is capable of very steep
transitions and, unlike conventional analog graphic EQs, what you see is what
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