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B2-GRQ-OpGuide-v9-031020.pmd
9.3. RECOMMENDED EQ USAGE
9.3.1. Set the Graphic EQ First
Because of the considerations discussed above,
Sabine recommends first adjusting graphic equaliza-
tion settings, before addressing use of FBX or para-
metric filters. Graphic EQ filters will compensate for
uneven system frequency response that arises from
room acoustics and system components, with the
ultimate goal of producing a balanced sound.
What constitutes a “balanced sound” is of course a
subject of endless debate. Suffice it to say that
making a system sound as good as it can is both a scientific and an artistic process. There are many
well-documented methods of optimizing your system, and useful measurement tools and techniques,
but ultimately the skill of the operator is the determining factor of sound quality.
So you may elect to adjust your graphic EQ settings purely on the basis of what sounds good to your
ears, or you may opt to use a reference microphone and Real Time Analyzer to set your system EQ,
or you may combine these techniques.
Here are a few suggestions that may prove helpful:
•
SET THE RANGE
. Before you make any adjustments, set your graphic EQ range to allow either
a ±6 dB or ±12 dB range of adjustment. The unit arrives from the factory preset to 12 dB range.
To change to 6 dB, simultaneously press both the delay up and down buttons on the Graphi-Q front
panel (for two channel units, either channel’s buttons will produce the same result). (NOTE: this
toggles the selection of 12 and 6 dB ranges, and will switch back to 6 if you’re already set to 12).
Whenever the range is set to 6 dB the LED in the lower right corner of the front panel will light.
•
BOOST = CUT
. Try to balance the degree of frequency cut and boost when you make your graphic
EQ adjustments. This will make before/after comparisons more accurate and meaningful;
otherwise, whichever condition is louder overall may sound better to your ears and cloud your
judgment. Additionally, due to the bell-shaped boost or cut characteristics of EQ filters, the more
extreme the boost or cut, the more “ripple” (peaks or dips centered at the EQ slider frequencies)
there will be in the resultant system frequency response.
•
VARY LEVEL AND LOCATION
. If you’re making adjustments on the basis of what you’re hearing,
listen to the system at various locations in the auditorium, and over a range of playback levels. Both
location and system gain can radically affect the perceived frequency balance.
•
REFERENCE MICROPHONE
. If you’re using a reference microphone and a Real Time Analyzer
(such as those integral to the Sabine Power-Q or Real-Q2), you may also wish to study the results
with the microphone at several locations. We recommend using a flat response, free-field reference
microphone such as the Sabine SQ1001.
•
INTERACTIVE FADERS.
Remember pushing up or down a range of filters is actually boosting or
cutting beyond the range of any individual slider, because adjacent filters overlap and the settings
of each combine.
9.3.2. Using FBX filters
Once your graphic EQ curve is set, you are ready to move on to setting FBX filters. Setting filters in this
order (graphic before FBX) means you’re likely to get more benefit from your FBX filters. If there are
frequency ranges attenuated or boosted by your system or acoustics that are not first compensated for
by graphic EQ, your FBX filters may cluster together, using several narrow filters to address a problem
better solved by one, wider filter, and more quickly exhausting available FBX filters.
9.3.3. Changing FBX filters to Parametric filters
Using the remote control (see
Section 8.2.5
) you can change FBX filters to parametric filters. This
allows you to manually change the width and/or the depth of the feedback filter set automatically. This
may prove useful if you set FBX filters and see that some have been placed close together. You may
be able to program a parametric filter in between two filters with a slightly wider width or depth, and use
one filter to do the job of two FBX filters. You can then reset FBX filters, rerun your setup, and get
additional gain by adding another feedback filter to your arsenal.
S
ECTION
N
INE
: S
UGGESTIONS
FOR
O
PTIMAL
U
SE
OF
THE
G
RAPHI
-Q2
Program you DON’T
LOSE when you use FBX
instead of a
1/3-octave EQ.
