The Standard DCX2496

The Good:

The DCX is a highly flexible digital crossover for loudspeaker builders or live sound systems. It can accept stereo analog or digital inputs and split the signal for tweeter, mid and woofer (or other configurations), sending the signals to 6 analog outputs. Parametric EQ and adjustable time delays are also possible, allowing correction of the speakers and room. The adjustable crossover slopes allow more flexibility than typical analog crossovers.

A Problem:

The features of DCX mentioned above are superb, however there is an achilles heel; the analog inputs and outputs have relatively high distortion compared to the best alternatives.

The type of distortion that is poor on these units is Intermodulation Distortion (IMD) which is not specified in the Behringer manual. IMD can cause a tiring and hard sound.

The solution - Modification

In fact, the DAC and ADC chips inside the DCX are high-end items from AKM and Cirrus Logic. Much of the music you listen to will have been recorded using these same converters, as they have been used inside audio interfaces from industry leader ProTools.

The distortion of the DCX is created by the analog signal conditioning circuits, not the converters themselves. Unfortunately, simply replacing the op-amp chips in the existing circuit does not correct the distortion issues.

To avoid replacing almost every part in the existing circuits, the solution is simply to replace the analog circuits in their entirety with something better.

Upgrade circuits available from BehringerMods are offered as a self-install kit and include a 'link PCB' that connects between the existing ribbon cable to minimize install effort. Note that removal of some parts and soldering is still required.

These new upgrade circuits allow the signal converters in the DCX to reach their full potential with low distortion and noise of all types.

Upgrade Circuit - The BehringerMods upgrade PCB conveniently handles both analog input and output conditioning on a single board for Inputs A,B and Outputs 1-6. Input C is not modified.

The signal levels are changed to 2V rms full-scale, matching well with domestic hi-fi equipment.

The input section is implemented using a fully differential op-amp from Texas Instruments (OPA1632), purpose made for driving audio ADC chips. The circuit can be fed from either a single-ended or balanced input. A dedicated voltage reference is used to provide bias for the ADC, allowing for the lowest possible noise level.

The output section is a 'floating balanced' design. It can perform 'active ground cancelling' even when used in single-ended systems.

The output circuit is built around Texas Instruments 'SoundPlus' OPA1652 op-amps allowing the full performance of the DAC chip to shine.

The circuit comes with DC blocking and power smoothing capacitors from respected brand Panasonic.

The Behringer DCX when modified with this new circuit is capable of less than 0.001% THD and IMD from analog input to output.

When used single-ended, Pin 3 must be grounded, either to Pin 1 or the connected equipment.

Learn more about the distortion types of the DEQ and DCX here: Proof of Upgrade Performance

Short FAQ here.

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