Behringer Stereo System CX3400 Manuel D’Utilisation

SUPER-X PRO CX3400 User Manual

Problems will be encountered only with unconventional setups (e.g. when the 

woofers are placed underneath the stage, while the midrange/tweeter systems 

are flown above it) or when long woofer horns are used. The latter are the subject 

of the following discussion.
First, measure the horn length. In the case of folded woofer horns this is anything 

but easy. Use a design drawing or open the cabinet (usually, a flap or cabinet side 

wall can be opened easily, for instance, to replace a defective speaker).
We use a horn length of 1 m as an example. It will make no sense to delay the 

signal, because the woofer signal arrives with a 3-ms delay at the “mouth” 

of the horn. So, you cannot achieve a correct runtime, unless you would 

delay the runtime of the remaining systems in the stack. The pulse response 

(the main reason for runtime correction), however, is mainly determined by the 

mid and tweeter ranges. What you can – and should – achieve though is phase 

coincidence at the crossover frequency. Which is exactly what the SUPER-X PRO 

gives you: free adjustability of the crossover frequency.
Calculate the frequency whose wavelength corresponds to twice the horn length. 

At this frequency the output signal will be reversed by 180° in phase when it 

comes out from the horn.
The frequency can be calculated as follows:

Use the known values (speed of sound in m/s; horn length in m) to calculate 

the frequency:

Now, using a crossover frequency of 171.5 Hz and reversing the polarity 

of the woofer output will result in an approximate phase correction, 

which can be fine-adjusted by applying some delay or shifting the 

crossover frequency a bit.

General remarks on runtime correction
Only one speaker stack each should be measured and corrected. Begin with the 

highest crossover frequency and work your way downward.

When the speaker offset is greater than 68.6 cm you can only move the speaker 

cabinets. Runtime correction is not the same as the signal delay applied to offset 

groups of speakers. Here, the entire signal must be delayed by a much greater 

amount (a suitable delay circuit is included, for example, in the BEHRINGER 

ULTRA-CURVE DSP8024).

Limiting the signal in the crossover network is the last resort to protect the 

system against overloading. Otherwise, improper handling by the user could lead 

to serious damage in several drivers.
Each frequency requires its own limiter/compressor control times. The higher the 

frequency, the shorter the control times. In the SUPER-X PRO, the control times 

for the single bands have been determined after long listening tests, in order to 

achieve inaudible gain adaptation instead of hard limiting.
The limiter threshold can be set from -6 dB to OFF and acts on all six limiters at 

the same time. Still, each limiter band works independently, with the LIM-LEDs 

lighting up as soon as the associated limiter is activated.
Please note that the limiters in the SUPER-X PRO are no “hard ratio” limiters, i.e. 

signal peaks can surpass the adjusted threshold by as much as 6 dB. Please make 

sure that your system provides enough headroom.

3.6.1  Limiter setup
On condition that you are using power amps and speakers that are compatible 

in terms of power rating, you should drive your amps under full load (i.e. 0 dB). 

Use pink noise from your analyzer as a sound source, turn the limiter THRESHOLD 

control to maximum and press the LIMITER button. Then, gradually cut back the 

threshold until just a few LIM-LEDs start flashing. Now, the entire system gain is 

limited to 0 dB.

To produce a very loud and deep bass response, the lowest band should be 

summed in a mono signal, while the remaining bands remain in stereo 

(the human ear cannot locate the source of low frequencies). By combining all 

woofer cabinets in one single cluster (the closer, the better) you can optimize 

their efficiency. Two woofer cabinets positioned next to each other produce an 

SPL that is 3 dB higher than that of two cabinets placed at a certain distance. 

Four cabinet give you as much as 6 dB, because low-frequency sound waves 

feature a spherical dispersion pattern. When the cabinets are positioned 

separately, the sound waves they radiate interfere with each other, 

while cabinets placed next to each other create one common wave front 

(compare two stones that are thrown into the water, either separately 

or together).
In stereo mode, the SUPER-X PRO can be switched to mono bass mode using the 

LOW SUM button.
When the LOW SUM button is pressed, the low-frequency signal portions 

in the left and right channels are summed up. The output signal is routed 

to the Low output of channel 1, from where it can be used to drive, for instance, 

a subwoofer cabinet.

When a driver radiates into open space via a horn, its efficiency increases. 

Over the past few years, so-called constant-directivity horns have gained 

widespread popularity, as they offer the advantage of producing a very 

regular dispersion pattern over their frequency range; however, the higher 

the frequency, the lower their efficiency. To make up for this drawback, 

the SUPER-X PRO includes a switchable pre-EQ for CD horns that ensures a flat 

frequency response even before equalization is applied. This pre-EQ raises the 

signal gain by 3 dB at 3.5 kHz, which then increases by 6 dB/oct. up to 22.5 kHz.