Behringer CX3400 manual Application

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3.5.2 Basics of electronic runtime correction

It is important to know how the dimensions of time and space are connected with each other, e.g. by using a tape measure and a pocket calculator.

Example: a delay of 2 ms corresponds to a distance of 68.6 cm; when you measure an offset of 30 cm you

can calculate the necessary delay as follows: 2 ms x 30 / 68.6 = 0.87 ms.

If it is impossible to measure the offset with an accuracy of at least 1 cm, you can perform the runtime correction with the help of a measuring microphone and tunable sine generator, using the SUPER-X PRO’s feature of variably adjustable crossover frequencies. More on this below.

The speed of sound is 343 m/s or 34.3 cm/ms approximately (hence, 2 ms of delay correspond to a virtual speaker offset of 68.6 cm). Frequency is measured in oscillations per second (1/s); the unit of measurement is Hertz (Hz).

For example, when you adjust a crossover frequency of 3 kHz between the horn and midrange systems, the wavelength l is calculated as follows: l = c / f (c = speed of sound; f = frequency). So, the wavelength at

3 kHz is:

34,3 cm/ms

=

34300 cm/s

= 11,43 cm

3000 1/s

 

3000 1/s

 

With a virtual distance of 68.6 cm, the control range of the potentiometer will provide at least six positions that ensure phase coincidence. Perhaps none of these positions will correct the runtime differences completely, for example, if the offset between the drivers is greater than 68.6 cm.

Is that important? It is, because only a system whose runtime differences have been corrected will be capable of:

1.reproducing pulse peaks correctly.

2.maintaining phase coincidence when the signal frequency moves away from the crossover frequency.

3.5.3 Runtime correction in a P.A. system using the SUPER-X PRO Midrange/high midrange/tweeter range

Before you perform the following steps to correct both runtime and phase, you should measure the offset between the drivers in cm and move the cabinets (or delay their bands), until you think they are aligned correctly. This will save you a lot of time later on. Now, do the fine adjustment as follows:

Using an analyzer

sUse pink noise as your sound source and connect the measuring microphone to the measuring input of the analyzer.

sAdjust the bands below/above the crossover frequency so that each one alone produces a 0 dB reading at the crossover frequency; mute the remaining bands. If both bands together produce a +3 dB reading, they can be considered in phase.

sNow, raise the crossover frequency by a factor of 1.5 and perform the same steps as above. Here, too, the analyzer should read +3 dB.

sFinally, check your setting by raising the crossover frequency by a factor of 1.4.

sHere, too, you can temporarily reverse the phase of one of the bands and check the sound for cancellations.

If no runtime correction is achieved

s Check whether the distance between the two drivers is or could be greater than 68.6 cm. If so, try to correct it by moving the speaker cabinets.

sIf this still doesn’t solve the problem, one of the bands could be reversed in polarity. Experiment with the front-panel PHASE INVERT button.

Sub-woofer/woofer/midrange

It is often claimed that phase or runtime correction below 150 Hz is unnecessary, because the sound waves feature a spherical dispersion pattern at such low frequencies. We disagree with this view.

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3. APPLICATION

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Contents PRO Hanns-Martin-Schleyer-Straße Behringer International GmbHWillich Safety Instructions Detailed Safety InstructionsSUPER-XPRO Foreword Table of Contents Introduction Design ConceptMulti-way speaker systems SUPER-X PRO the high-end frequency crossoverBefore you begin Control elementsDesign Concept Active control elements on the rear panel of the SUPER-X PRO MID Output connector. Output for the Mid band signal Design Concept Design Concept Setting the input levels Setting the output levelsApplication ToolsSetting the crossover frequencies Runtime CorrectionApplication Limiters of the SUPER-X PRO Installation LOW SUM functionCD Horn function Rack mountingMains connection Audio connectionsSpecifications XLRSpecifications Warranty § 1 Warranty Card
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CX3400 specifications

The Behringer CX3400 is a versatile and highly regarded crossover that has become a staple in professional audio setups. This unit is designed to ensure optimal sound quality by efficiently distributing frequencies to appropriate loudspeakers, making it an essential component in sound reinforcement systems, PA setups, and live performances.

One of the standout features of the CX3400 is its three-way or four-way crossover topology, which allows the user to manage sound frequencies with precision. It’s equipped with independent adjustable output controls for each of its outputs, enabling users to tailor the audio experience to fit the specific requirements of any venue or application. The ability to adjust the crossover frequency range from 50 Hz to 6 kHz makes it suitable for various configurations, whether for subwoofers or high-frequency drivers.

Another significant aspect of the CX3400 is its built-in low-pass and high-pass filters. This functionality ensures that low frequencies are directed to subwoofers while high frequencies are sent to tweeters, thus maximizing the efficiency and clarity of each speaker in the system. The filters operate at a steep 24 dB per octave slope, which aids in maintaining the integrity of sound reproduction and minimizes overlap that can lead to distortion.

In terms of technology, the CX3400 features independent audio signal processing capabilities, allowing for more refined control over the audio output. The unit includes a high-quality 24-bit A/D converter and a 24-bit D/A converter, which significantly contribute to the overall audio fidelity and dynamic range. The CX3400 also features balanced XLR inputs and outputs, ensuring that the audio signal is transmitted with minimal interference and noise.

The build quality of the Behringer CX3400 is also noteworthy. It’s designed to withstand the rigors of live performance environments, with a durable chassis that ensures reliability. The user interface is straightforward, with clear, intuitive controls that make it easy to set the desired parameters quickly.

In summary, the Behringer CX3400 crossover is a powerful tool for audio professionals, offering precise frequency distribution, advanced filtering technologies, and solid construction. Its combination of versatility, performance, and user-friendly design makes it an excellent choice for those looking to enhance their sound systems, whether in live settings or recorded applications. The CX3400 continues to be a trusted device for audio engineers, ensuring that every musical element reaches its full potential.
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