The Standard DEQ2496

The Good

The DEQ features graphic and parametric EQs implemented in the digital domain. The DEQ can be used as an ADC, DAC and room correction processor.

A Problem

The features of DEQ 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 these units suffer is Intermodulation Distortion (IMD) and Multi-tone Distortion (MTD) which is not specified in the Behringer manual. IMD and MTD are test signals that represent the complex nature of real music, unlike pure test tones. The type of distortion produced is non-harmonic so it sounds un-pleasant and can cause a tiring, hard sound.

The solution - Modification

In fact, the DAC and ADC chips inside the DEQ are high-end items from AKM and Cirrus Logic. The distortion of the DEQ is created by the analog signal circuits, not the converters themselves.

Simply replacing the op-amp chips does not correct the distortion issues. To achieve the desired performance, almost every part in the analog circuits must be replaced with something better.

Upgrade circuits from BehringerMods are a self-install kit that include a 'link PCB' to connect with the existing ribbon cable to minimize install effort. However, removal of parts and soldering is still required.

The BehringerMods new upgrade circuit allows the signal converters in the DEQ to reach their full potential with low distortion and noise of all types.

Upgrade Circuit Detail

The BehringerMods upgrade circuit conveniently handles both analog input and output conditioning on a single board for the XLR Inputs and outputs. The TRS jack outputs are not upgraded.

The signal levels are set to 4V rms full-scale.

The input section is implemented using low noise LM4562 op-amps from Texas Instruments and a dedicated voltage reference to provide ADC bias. The circuit can be fed from either a single-ended or balanced input.

The output section is a floating balanced design built with Texas Instruments LM4562 op-amps. It can perform 'active ground cancelling' even when used in single-ended systems.

All electrolytic capacitors on the circuit for DC blocking and power smoothing are from respected brand Rubycon.

The Behringer DEQ when modified with this new circuit is capable of 0.001% THD, IMD and noise from analog input to output.

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