Digital Room Correction with the Behringer Ultracurve Pro DEQ2496

Digital Room Correction with the Behringer Ultracurve Pro DEQ2496

September 1, in Hi-Fi Systems Reviews

Listening rooms are a problem; at least my listening rooms have always been a problem. A number of years ago I visited an audio shop where I was invited into a listening room that held components each costing the price of my car. The listening session that followed has always stayed with me. It was the first time I heard the various instruments within my favorite recordings floating individually in space, in fine detail and free of any hint of harshness in the frequency range. While each component that made up the system might arguably have been considered best in its class, I believe the sound I was hearing was due mostly to the listening room itself, which was at least twice the size of any room in my house, heavily damped, with all sorts of odd looking tubes and panels in various places along the walls and corners.

As much as I would like to, I do not have the luxury of dedicating one room of my house solely to the act of listening to music. Instead, I’ve had to fit my stereo systems into rooms that are lived in, and the extent of room treatment has been limited to speakers that are well placed but out of the way, a thick carpet, semiplush furniture and bookshelves. I had always considered the sound I heard that day years ago to be a distant and unaffordable goal.

The vision in my mind’s ear hasn’t changed. That vision consists of a full range sound, a broad soundstage when called for; an engaging and lively sound full of low level detail but free of upper midrange glare. Recently, a couple of changes in the manner in which I approach audio has allowed my goal to become much more of an affordable reality. One of the components that have allowed me to get at such a sound is the Behringer Ultracurve Pro DEQ2496.

Behringer Ultracurve Pro DEQ2496 front

Behringer DEQ2496 review

The DEQ2496 is not a component that one would normally find in a home stereo system. The manual describes it as an “ultra highprecision digital 24 bit / 96 kHz EQ / RTA mastering processor”, and its roots lie firmly in the live sound arena. I like to describe the DEQ2496 as a $299.00 component that can maximize the performance of an audio system by alleviating some of the problems that naturally arise when speakers interact with a room.

The DEQ2496 is primarily an equalizer, but its equalization occurs in the digital arena via the use of digital signal processing, and hence is free from the signal degrading properties that were common to many analog equalization systems. The DEQ2496 has a broad array of features, but of particular interest to owners of a home audio system are the unit’s excellent and transparent equalization capabilities, as well as its ability to be used as an external digital to analog converter (DAC).

Behringer DEQ2496

Why use equalization? One reason is bass response. The wavelength size of a low bass note is quite large. Sound waves will be reinforced or nulled in different areas of a room depending upon room reflection and absorption, causing peaks at some frequencies and dips at other frequencies. Frequency peaks can be powerful enough to mask the sound of other nearby frequencies. For example, at the listening position in my room, I have a large peak centered at 35 Hz that is about ten decibels above average, and another near 120 Hz. Room peaks and dips occur at all frequencies, but as the frequency rises the affects tend to be less pronounced. At lower frequencies, the peaks and dips are stable across larger areas of the room, but at higher frequencies the peaks and dips can be radically different at a distance of a few inches.

Behringer Ultracurve Pro DEQ2496 back

For this reason, equalization is generally recommended for bass frequencies as the effects can be positive over a relatively large listening area. Equalization is not usually recommended for higher frequencies as a cut or boost to even out the response at the listening position could cause a worse problem only a foot to the left or right. However, if you find that your speakers are a little bright or forward sounding, equalization can still be effectively used in the midrange and treble by applying minor cuts across a wider range of frequencies, as apposed to the more specific equalization used for evening out the room response at low frequencies.

Behringer Ultracurve Pro DEQ2496

Before diving into details regarding the equalization capabilities of the DEQ, I will pass along information regarding the unit’s DAC. The DEQ2496 will accept sampling frequencies up to 96kHz with word lengths up to 24 bits. The unit has two digital inputs: a transformer balanced XLR input that will accept an AES/EBU or S/PDIF signal, and a toslink optical input. The DEQ2496 also has digital outputs of the same type if one wishes only to use the unit as an equalizer in the digital domain. It is worth mentioning that the DEQ2496 also features analog inputs that feed an analog to digital converter, so applying digital equalization to an analog source is possible. All analog inputs and outputs are balanced XLR connections, so XLR to RCA adapters are needed to use the unit with the single ended RCA inputs and outputs common to most consumer audio equipment. In judging the unit as a DAC, I bypassed all of the equalization functionality of the DEQ2496 and compared the sound directly to the internal DAC of my Marantz SA-8260 SACD player. The Behringer has a gain offset function that allows level adjustment in half decibel steps, so I could easily match output levels to that of the CD player. I fully expected the Marantz, at three times the cost, to trounce the sound of the three hundred dollar Behringer, but the sound of the two units was remarkably similar playing redbook CDs. I would give a nod to the Marantz as having a slightly smoother sound with increased soundstage depth, specifically in the midrange and upper frequencies, although the sound of the DAC in the Behringer was in no manner objectionable. With the equalizers bypassed, the Behringer had a very slight tizziness to the upper frequencies in direct comparison to the Marantz, but with the equalizers switched in and properly adjusted, I would much rather use the Behringer as a DAC than the Marantz. In testing the unit as a DAC, I tried both the toslink input fed directly from the toslink output on the CD player, and the XLR input fed from the coax output on the CD player with an RCA to XLR adapter at the input of the Behringer. I preferred the sound of the toslink connector. The XLR input had more glare in the upper frequencies. This might be due to the toslink connection keeping the two units electrically separated, or the less than ideal use of adapters when connecting to the XLR input. Interestingly, when I fed the digital outputs of the Behringer to another external DAC which had a proper AES/EBU balanced connection, I preferred the sound of it over the toslink feed.

Where the Behringer really shines is in its use as a digital equalizer, particularly its room correction capabilities. The DEQ2496 has three equalizer modes: parametric, graphical, and dynamic. There is even a forth mode which employs extremely narrow notch filters meant to effectively deal with feedback in a live sound situation. The unit can employ all of the equalization modes at once if so desired, although I have only used the graphical and parametric modes.

The DEQ2496 has built in real time analysis (RTA) features that can aid you in identifying problems in the room response of your speakers. The unit has a pink noise generator and a 61 band real time analyzer which, when used together with the Behringer ECM8000 measurement microphone, can give you a good picture of frequency response problems at the listening position. The unit has an autoEQ routine, which will automatically adjust the graphical equalizer to any target curve you desire, although I have achieved the most natural sounding results by only using the parametric equalizer to dial out peaks in the room frequency response.

A parametric equalizer is an equalizer that allows you dial into a specific frequency, apply a boost or cut, and specify the width of the affected frequencies around the chosen center frequency. The parametric EQ built into the DEQ2496 allows up to ten bands of adjustment per channel. Each band has an adjustable center frequency of 1/60 octave per step between 20Hz and 20kHz, an effective width of 1/10 octave to 10 octaves, with a 15db cut or boost adjustable in half decibel increments.

Using the parametric EQ only to flatten out frequency response peaks, I was able to quickly eliminate 12-decibel humps of various widths around 36Hz, 119Hz and 164Hz from the left channel. I applied similar but customized peak removals to the right channel since each channel can be adjusted separately if desired. The DEQ2496 has the ability to save all settings to memory and assign names to the various memory settings. The memory settings allow a convenient manner to rapidly compare the sound of various settings.

It is hard to imagine the type of effect the removal of peaks can have on system performance if you haven’t enjoyed the luxury of hearing a well equalized room. Bass response, even though less loud, becomes seemingly deeper and more detailed when rogue frequencies are not stomping all over the rest of the spectrum. If your speakers are too forward sounding, a small cut between one and three kHz can pull the soundstage back a bit and reduce the upper midrange glare that can cause listener fatigue on hot recordings. The reduction of frequency peaks allows an increased perception of low level detail and allows the listener to hear individual tonal colors more easily. Instrument separation within the soundstage becomes more pronounced, and stereo width and soundstage depth increases due to the cleaner frequency response.

To get a feel for the sound of what a smoother frequency response offers, I listened to some of my current favorites both with the DEQ2496 in the system and out, switching between the two via the selector switch on my preamp. Lately I have been smitten with Jacqueline du Pré’s wonderful cello work in Elgar’s Cello Concerto (Sony Classical). The cello stands out nicely in the front of the soundstage in this recording. With DEQ in the system, the orchestra resolves from a semiamorphous background into individual instruments. In particular, the double bass takes on more tone and depth, and the tympani resolves itself to an initial strike and subsequent decay instead of a general “whump”. At the same time, the cello comes further out to the front of the soundstage, with more delicacy and detail during soft bowing and more bite in crescendos.

My present pet sing-along-pop-song is Guster’s “Satellite” from the recently released “Ganging Up on the Sun” (Reprise). With the DEQ in the system, the opening acoustic guitar chords jangle freely and lightly. The bass guitar finger slides are filled with tone. Without the DEQ, the guitar is weighed down, and the rhythm seems a bit sluggish. I would like to give a more detailed comparison of this recording, but when I put the DEQ back in I began singing and was lost to my task.

One of my long standing favorite compositions is the title track of Pat Metheny’s “First Circle”. The composer beautifully mixes acoustic guitar, piano, vocals, a variety of percussive instruments and bass guitar into a very dynamic arrangement made of alternating odd time-signatures that never bores no matter how often I hear it. Without the DEQ, the bass line wanders upon notes that play much louder than others, burying some of the lighter tones in the mix. With the DEQ, the bass is deep and present, but not overpowering. Lyle Mays beautiful piano solo begins delicately with soft presence, picking up dynamics and pace with the accompanying ride cymbals, resolving into an explosive crash of the china cymbal and a walloping of the floor toms on the opposite side of the stage. When listening with the Marantz directly feeding the preamp, it was easy to remember to switch the equalizer back in. When listening through the DEQ2496, my primary goal of comparing the sound with and without the unit was often forgotten.

Some people might balk at the idea placing the inexpensive DEQ2496 into system made of much more expensive components. Would the three hundred dollar components adversely affect a system made up of three thousand dollar components? To answer this question, I brought the DEQ2496 to friend’s house and we placed it into the system between a transport and separate DAC. After measuring the room response and applying some to limit peaks, it was clear that the room correction capabilities of the DEQ2496 offered substantial improvements to an already very good system when used in the digital domain. How could a three hundred dollar piece of equipment offer improvements to a fifteen-plus thousand dollar system? The answer lies in the fact that a room must be treated as a very important component of the system, and the Behringer gives you the ability to do just that.

Boosting dips in the room response is generally frowned upon for the following reasons. Equalizing a boost at the listening position can cause a severe boost in another area of the room. Achieving a six decibel boost in level requires a doubling of power, making both the amplifier and the speakers work harder. If you listen to music in one general area of your room, have amplifier power to spare and don’t listen to music at volume levels which tax your speakers, then equalizing out a dip in the low frequencies may be something to try. With the Behringer, you can apply a 15 db boost as well as a 15 db cut to any chosen frequency. It is important to remember that using the Behringer to boost frequencies will require an associated offset to the overall digital level so that the unit doesn’t clip. Fortunately, the DEQ2496 has excellent metering capabilities that can advise you of the occurrence of a clip, and it is a simple matter to reduce the overall level of the equalizer.

All in all, the Behringer DEQ2496 has provided the most effective performance per dollar ratio of any individual component I’ve had in my system, but unfortunately, there are some drawbacks to the unit. The DEQ2496 has no feet to rest upon. The rack mount handles are removable if desired, and feet such as Vibrapods could easily be substituted. The unit has a great many features, most of which will not be used in a home audio setting. Thus, it takes a while to become comfortable with the user interface, and repeat readings of the rather minimalist manual are generally required to use the features most effectively. As mentioned earlier, the unit only employs balanced XLR connections for the analog inputs and outputs, so some type of adapter must be used if your preamp or integrated amp includes only single ended inputs. Quality control may also be suspect. The first unit I purchased was unusable out of the box. I had no trouble returning it for a working unit, and have since enjoyed excellent performance.

At a list price that is less than many brands of interconnects, the Behringer Ultracurve Pro DEQ2496 brings a great level of effectiveness for a very small cost. There are a number of audiophile caliber digital equalization systems on the market, but all others I am aware of cost thousands, not hundreds, of dollars. The improvement that can be wrought from a smattering of judiciously applied subtractive equalization can be equivalent to what would cost thousands of dollars if applied to the more traditional components of an audio system.

Associated Equipment:

  • Behringer ECM8000 measurement microphone
  • Marantz SA8260 SACD player
  • Transcendent Sound Grounded Grid preamplifier
  • B&K ST-202 Plus amplifier
  • Ellis Audio 1801b speakers
  • Analysis Plus Oval 9 speaker cables
  • Silver Audio Silver Bullets 4.0 interconnect cables Mogami Gold balanced XLR interconnect cables Signal Cable Magic Power Digital Reference power cord.

Additional info about Behringer DEQ2496

external link: http://www.behringer.com/EN/Products/DEQ2496.aspx

from affordableaudio

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3 comments

  1. Daniel Fagen February 15, at 5:57 pm

    Hello,

    I am quite interested in this unit.Due to the fact my present two channel high end set up is in a very challeging room for acoustics.I get overwhelming bass that is not tight, and mid bass. that interrupts the treble range that becomes and bit too hot.I would like to be able to achieve a flatter response without disrupting the quality of sound my system can produce.Overall I would just like my sound a bit more neutral.But my other problem is that my gear is more or less set up for single ended input and outputs.And so are my interconnects.

    Any input would be highly welcomed.

    Thanks,

    Dan.

    reply
  2. Stephen Mollner May 28, at 1:36 pm

    Could not agree more! What a terrific device to enhance the sound of any system. I have the good fortune to own the Sanders Sound System 10D (with two Magtech amplifiers) that uses the companion Behringer DCX2496 digital crossover. Of course, I connect them digitally and the sound has gone from great to beyond amazing!

    reply
  3. Stefano November 10, at 10:09 pm

    First of all a well done for this article because explain exactly how this machine should be used to achieve the best results. First time I’ve used it was ten years ago upon suggestion of a friend of mine and it has always stayed in my setup. The way to use it o is exactly as you say to reduce excessive peaks in the low range freqs. Maybe if you use it in conjunction with the REW software will give more precision in identifying the peaks
    Lately I’ve purchased an OpenDrc with acouratedrc but I kept the low freqs corrected mostly by the behringer and added the minidsp in the chain all using digital connections just to take advantage of the fir filter that helped improved the soundstage on the up mid and high frequencies. This gives me the advantage of the accuracy of a fir filter together with the flexibility of a rta peq and geq
    A really Great piece of equipment !!

    reply

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