graphs in a monitor rig at low levels of
cut, you probably were using a graph with
“proportional Q.”
Old school models of graphic equalizers have proportional Q or “variable
Q” filters, meaning that they’re sharper
at extreme amounts of boost or cut, but
at lower gain, the shape of the filter is
broad. The result is that small amounts
of adjacent boost combine to provide an
overall gain that is greater than indicated
by the physical controls on the front
panel because of the filters’ overlap.
MORE RECENT PIONEERING
In the ’80s, Rane Corp. pioneered
the development of “constant Q” or
“constant bandwidth” filters
for graphic equalizers, which
maintain the same narrow Q
or bandwidth at low boost or
cut as they have at high gain,
making them better suited for
treating room modes or for
feedback control. These days
many brands of graphic equalizers provide constant Q filters, including Ashly, Carvin,
dbx and XTA.
In the ’90s BSS introduced
its FCS-960 Dual Mode
graphic equalizer which provided constant Q filters with
the ability to sharpen their
response by engaging a single
switch. In the “normal” mode,
the 960’s filters provide smooth
summation from one filter to
the next, even at large amounts
of boost or cut, better for use
as tone controls for sweetening. In the “fine” mode, its
filters are sharpened to more
precisely cut or boost frequencies within the intended third
octave range, earning them
favor amongst engineers over
other graphic equalizers for notching
room modes and for feedback control.
A decade ago, the Protea from Ashly
introduced affordable remotely controlled programmable graphic EQ with
their 4-channel 4.24G digital EQ. Its
hand-held LCD 4.24RD remote controller can be used over a pair of XLRs
up to 1,000 feet long. Its 48k Hz sampling rate helped monitor engineers
grow accustomed to 1. 46 ms latency
in monitor mixing. It provides cut and
boost of up to 15 dB with a Q of 3. 2
(0.45 octave).
Shortly thereafter Sabine introduced its Graphi-Q, a digital equalizer
with an analog front-panel interface.
BSS FCS-960
Ashly Protea 4.24G
In addition to a compressor/limiter,
digital delay and high- and low-pass
filters, it also incorporates a dozen
parametric filters per channel that can
also be used as Sabine’s FBX Feedback
Exterminator filters. It can automatically “ring out” a monitor mix in Turbo
mode, placing narrow FBX notch filters
at frequencies where feedback occurs.
Another notable feature is the ability
to define the bandwidth of its graphic
filters from 0.5 to 1.0 octave.
A few years ago, we heard from many
live sound guys that got hooked on the
EQ Station from TC Electronic. It’s a
2U DSP frame with eight channels of
graphic EQ, each with an additional
12-band parametric EQ, as
well as 3-band dynamic EQ,
delay and limiter. It offers
four popular graphic EQ
types, including BSS 960,
KT DN27 and their own
borrowed from the TC 1128.
Like its predecessor’s companion 6032 remote motorized fader “head,” the EQ
Station also has a moving
fader remote, the Motofader
64 with 29 motorized 60 mm
faders, which vaguely resemble a DN27.
Sabine Graphi-Q
TC Electronic EQ Station
ON-BOARD EQ
Nearly all digital consoles
have on-board graphic
equalizers, and most can
use their moving faders to
represent the settings of the
faders of their graphic EQs
and adjust them.
One favorite is the LS9-
32 from Yamaha. It is able
to use all of its faders to represent a 31-band graphic EQ
in its entirety; the only digital console that we’re aware
