The Standard DEQ2496
The Good:
The
DEQ is sold by Behringer as a processor for mastering studios. It
features graphic and parametric EQs implemented in the digital domain.
To enable analog connections, it contains both an ADC and a DAC.
Through a microphone (ECM8000) the DEQ can measure the response of a
speaker / room combination and correct it to the desired target
response. In the 20Hz - 300Hz range this is ideal for improving uneven
resonant bass.
Input connections: 1 pair XLR analog, 1 AES/EBU digital and 1 Toslink
Optical. Outputs connections: 1 pair Main XLR analog, 1 pair Aux TRS
analog, 1 AES/EBU digital and 1 Toslink Optical.
A Problem:
The features of DEQ 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 solution - Modification
In
fact, the DAC and ADC chips inside the DEQ 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
DEQ is created by the analog signal conditioning circuits, not the
converters themselves. Unfortunatly, simply replacing the op-amp chips in the
exisiting circuit does not correct the distortion issues. The solution is to replace the analog
circuits in their entirety with new circuit designs.
Upgrade circuits
availible from BehringerMods are offered as a self-install kit or with
installation provided by BehringerMods for those less confident at soldering.
These new upgrade
circuits allow the signal converters in the DEQ to
reach their full potential with low
distortion and noise of all kinds.
Upgrade Circuit - The
BehringerMods upgrade PCB conviniently handles both
analog input and output conditioning on a single
board. The DEQ kit also includes a 'link PCB' which
reduces the soldering nesicary to install the upgrade.
The input section is implimented using a fully
differential op-amp from Texas Instruments (LME49724),
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 designed to emulate the
behaviour of a transformer coupled circuit, enabling
it to provide active noise cancellation whether
connnected single-ended or balanced. The design is
built around Texas Instruments 'SoundPlus' OPA1652
op-amps allowing the full performance of the DAC chip
to be heard.
The circuit comes with through-hole mounted DC
blocking and power smoothing capacitors from arguably
the most respected brand Panasonic.
The Behringer DEQ when
modified with this new circuit is capable of less than
0.0005% THD and IMD from analog input to output.
The input and output signal
level for 0dBFS digital is 3.5V RMS. The signal elvel switch
on the rear of the DEQ will be ineffecitive after upgrade.
Learn more about
the distortion types of the DEQ and DCX here:
Proof of Upgrade Performance
Short FAQ here.
Pricing can be found in the the Online Shop
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