Filter
Top Products
8
Operating Manual - DPX-100 Graphic Equalizer - Compressor/Limiter
equalizer effectively, you need to translate your idea of
the tone you want to produce into a range of numerical
frequencies. This is simple after a little practise. Here are
a few references which are useful for starting points:
- Very low bass (the “wind” in a kick drum,
almost felt as much as heard -40Hz-80Hz.
- The low register of a male voice - 200Hz
- The low register of a female voice - 350Hz
- Lower midrange (“warmth” frequencies) -
400Hz-1KHz
- Upper midrange (“harshness”, snare drum
“bite”, “hot” sound) -2.5KHz-4KHz.
- Sibilance (“sss” sounds, cymbal “sizzle”) -
8KHz-15KHz.
Try using these starting points as a guide when
you want more or less of these types of sounds. Adjust
by ear from there. It is always a good idea to remember
that a little equalization usually works out much better
than a lot, and that there are many audio problems which
can not be solved with equalization alone.
Feedback Control
A graphic equalizer can be used to provide some
control over moderate feedback problems, but does not
have enough flexibility or resolution to handle severe situ-
ations. You will achieve the best results when you can
eliminate one or two feedback points by setting one or
two sliders for no more than a 6dB cut. Often you can
find a feedback point by boosting sliders in succession to
determine which frequency ranges contain the feedback
modes, and then cutting those ranges. Be very careful in
this process to avoid explosive feedback and possible sys-
tem and hearing damage! If you find feedback points
with many equalizer bands, remember that cutting every
band may not help (all you will do is reduce system gain).
The combination of a graphic equalizer for tone control
and a parametric equalizer (such as the Ashly PQX-571
or PQX-572) for feedback control is highly recommended.
Console Channel Equalization
Many mixing consoles provide only simple equal-
ization for individual channels. If your console has chan-
nel inserts, you can patch your graphic equalizer into a
channel that’s being used for something important and
use it to tailor the sound of this channel exactly the way
you want.
Large Room Equalization
Large rooms tend to suffer from multiple reflec-
tions with long time delays, long reverberation times, and
“ring-modes”, all of which lead to reduced intelligibility
and a generally “muddy” sound. As sound travels long
distances through the air, high frequencies are attenuated
more than low frequencies. In general, large rooms ben-
efit from some low frequency roll-off, high frequency
boost, and attenuation of ring mode frequencies. As in
the case of feedback control, a graphic equalizer can help
reduce an isolated ring-mode or two, but a tunable nar-
row-band equalizer such as a parametric is more effec-
tive here.
8.2 COMPRESSOR/LIMITER APPLICATIONS
As the functional name implies, a compressor/
limiter can be divided into two basic categories, limiting
and compressing. When used as a protective device to
prevent audio levels from overloading systems such as
tape recorders, power amplifiers, speakers, or transmit-
ters, it is generally referred to as a limiter.
It may also be used to create special effects and
unusual sounds for recording and musical performance
by deliberately reducing the dynamic range of a signal,
creating a much louder or fuller sounding signal without
increasing the loudness peaks, in which case it is referred
to as a compressor.
The Limiter As A Protective Device
The DPX-100 compressor/limiter section pro-
vides fast and accurate gain control for the prevention of
sound system overload due to unexpected transients.
Sound system distortion is usually the result of amplifi-
ers running out of power, in which case nice round wave-
forms turn into harsh sounding squared-off waveforms.
Looking at it from the perspective of the speaker dia-
phragm, this means that, whereas in normal operation the
diaphragm is required to accelerate, slow down, smoothly
change direction, and accelerate again, distorted opera-
tion requires an instant acceleration, instant stop, a change
of direction, and instant acceleration again.
Since speaker diaphragms are subject to the laws
of physics, they won’t take this kind of punishment for
long. The diaphragm may shatter, or its voice coil may
overheat. In addition to the damaged caused by sustained
overload, the speaker may also be damaged by occasional,
one-shot high level overload, for example, the sound of a
microphone falling face-first onto a hardwood floor. Even