Applications; Tools; Setting The Input And Output Levels; Correcting Problems - Behringer SUPER-X PRO CX2310 User Manual

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SUPER-X PRO CX2310 User Manual

3. Applications

You will need some tools to help set up the SUPER-X PRO to its optimal
configuration. To set up the crossover frequency you need to know which
frequency range a loudspeaker stack covers, over which range the sound
energy is linearly transmitted, and where reductions or increases in the
frequency response occur. In addition, every room has different size and quality
characteristics. These strongly influence the sound response, since resonances
and reflections in the different frequency ranges can also lead to reductions
or increases in the sound picture. You will need suitable equipment in order
to be able to recognize and compensate for these features.

3.1 Tools

You will need a high-grade microphone for making measurements.
This should have a frequency response that should be as linear as possible
(e.g. the BEHRINGER measurement microphone ECM8000) and at least linear
over the range from 90 Hz and 15 kHz. Place the microphone about 5 m. in front
of the speaker system and between the diaphragms of the two frequency bands
you wish to measure. When using a measuring microphone to set the levels for
the individual frequency bands and the crossover frequencies, you should only
operate one loudspeaker stack. For optimal settings you will usually need
to reposition the microphone between two successive measurements.
When used in combination with a measuring microphone and a generator
producing pink noise via an input into the P.A. mixing console, an analyzer
will show the sound energy distribution over the individual frequency bands
(usually in 1/3 of an octave). The BEHRINGER ULTRA-CURVE PRO DSP8024
equalizer/analyzer is the ideal tool for this application.
When listening to the overall sound of your system, you should walk around
in the audience area and try to detect resonance frequencies or cancellations.
The sound should be optimized for the position where most of the audience
will be gathered, without however neglecting other areas. This often means
that the system must be operated in mono. Whenever you use technical aids
such as analyzers, measuring microphones, etc., you should check the desired
results with your own ears.
◊
BEHRINGER accepts no responsibility for any damage or destruction
of loudspeakers arising from improper or incorrect use of the
SUPER-X PRO and in particular from actions which are in contravention
with the clearly stated procedures given in this manual.

3.2 Setting the input and output levels

Both inputs offer a gain or loss of up to 12 dB. Normally, the output level on the
mixing console and the input sensitivity of the amplifiers are identical, i.e. 0 dB
at the mixing console corresponds with 0 dB at the amplifiers. This means that
there is full control over the amplifiers. In this case the SUPER-X PRO should
have no effect on the system level and all input and output level settings should
be set at 0 dB. Where e.g. a home recording or disco console is being used with
an operating level of -10 dBV but the amplifiers need +4 dBu for complete
control, then an additional gain of 12 dB must be provided between them.
In this case the INPUT control of the SUPER-X PRO should be set to the maximum.
The output levels of the single bands can be raised/lowered by as much as 6 dB.
To achieve a linear frequency response in the system, all output levels should
be adjusted with the help of an analyzer. To check the crossover frequencies and
levels, mute all outputs except for one, and play back pink noise over the system
at an appropriate volume level. When you now switch on the adjacent band,
the level measured around the crossover frequency should go up by 3 dB.
Repeat this process for all crossover frequencies.

3.3 Correcting problems

Check the entire frequency response of the system. Rooms have quite
an impact on the frequency response of speaker systems, due to resonance and
various reflections, so you cannot expect to achieve a linear frequency response
right from the start. To achieve this, you need an equalizer such as the
ULTRA-CURVE PRO DSP8024 or the ULTRA-GRAPH GEQ3102. Look for drop-outs
around the crossover frequencies! If the frequency response is very irregular,
then it can make sense to grade adjust it using the frequency crossover,
before using an equalizer (EQ). The errors in the crossover frequency must then
be as far as possible corrected using the EQ.
If the loudspeaker diaphragms in a multi-way system are not exactly aligned
along a vertical axis, the varying distances between the sound source and
the listener result in phase errors and cancellations (also known as the
"comb filter effect"). Particularly in the higher frequencies it is important,
due to the shorter wavelengths, to position the diaphragms above each other
and not next to each other. The various types of construction used in individual
systems (horns, bass reflex cabinets etc.) still give rise to run time differences,
even where the front sides of all systems are aligned vertically above each other.
In this case a run time correction must be made by electronic means. This can
be done by using a delay function. Run time differences can be compensated
by delaying the frequency bands over a range of milliseconds. This helps avoid
loss of sound quality, particularly in the high tone ranges.
◊
Runtime correction is not the same as phase correction. If a speaker
system has the same run times then it also has the same phases
(unless the polarity of a cable has been reversed). However the
opposite is not necessarily true.

3.4 Setting the crossover frequencies

The frequency range from which the crossover frequencies can be selected,
can be one of two ranges—from 44 to 930 Hz and from 440 Hz to 9.3 kHz.
To set the crossover frequencies, please first read the manufacturers'
specifications for the individual loudspeaker components. To use the capacity
of your system at its best you should set up the crossover frequencies in
accordance with the frequency diagrams on the individual loudspeaker boxes.
Further, the crossovers should not lie on peaks or drop-outs. Look for a range
with the flattest possible curve. If folded bass horns are being used, then the
length of the horn path must also be taken into account, since the run time
displacements arising from differing long paths can also have a negative effect
on the frequency development (see chapter 3.3).
◊
Never operate loudspeakers or horn drivers below the limiting
frequency specified by the manufacturer!

3.5 SUBWOOFER output

To achieve a very loud and deep bass playback the SUPER-X PRO has an additional
mono subwoofer output for 2-way and 3-way operation. In this sense the
CX2310 is a stereo 2-way + mono 1-way or mono 4-way frequency crossover.
The subwoofer signal is mono, since people cannot sense the location of lower
frequencies. Another reason is that combining all bass signals into a single signal
produces an excellent effect. This is because two bass speaker boxes combined
together produce 3 dB more sound pressure than if they were separated from
each other by a small distance. The increased pressure is due to the speakers
producing a single wave front. With four loudspeaker boxes the increase is 6 dB.
The reason here is the spherical shape of the expanding low-frequency sound
waves. Bass boxes which are separate from each other can mutually disrupt each
other where their sound waves meet (what happens here can be easily imagined
if you throw two stones into water—first separately and then stuck together).