DEQ2496 amazing! Personal review

Discussion in 'AV Receivers' started by JamesDB, Mar 19, 2004.

  1. JamesDB

    JamesDB Stunt Coordinator

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    Well, after a long wait the Behringer DEQ2496 is in the house and hooked up. I thought I’d share some of my experience with this EQ. I purchased it with the ecm8000 RTA mic.
    I am currently using it to EQ out my sub and correct for any standing waves and other reflection problems I had been experiencing.

    Although I have used various higher end pro RTA/EQ systems, I just could not justify the cost of purchasing one for my home. I had been eyeing the DBX Driverack PA for a while but still felt that it was a bit expensive and didn't do the 96kHz minimum sampling rate I was looking for. I think the noise floor is a bit better than the Behringer, but I soon learned that in my home it would make no difference.

    Setup

    Hooked up to Denon 3803 RCA out into XLR in DEQ2496
    DEQ2496 to Mackie HRS120 sub via XLR

    I live in a rather quiet cul-de-sac and hooked up the mic for initial RTA readings. The noise floor of this device was around -100 -- -95 dB which can be see on the RTA screen. Additionally there was also noise being picked up by the mic in the -95 -- -85 range from things like a truck idling down at the end of my street, a bird chirping etc. (Funny, a lot of this was in the very low bands or high bands). Very sensitive mic indeed. This made me feel nice though that I did not get something far more expensive since a quieter device would not have seen true benefits in my house.

    After dialing in a pink noise level that was close to my listening range I started the GEQ RTA between 20 and 100Hz. It worked rather well because on reruns I keep getting the same results. There are 8 bands available between that range in mono. I copied them manually over to the PEQ where I adjusted the Q a bit to smooth out the curve. Given that I have only two parallel walls in my listening room I was surprised at how bumpy my curve was.

    Then I added a hard limiter with a strong attack which would protect my sub from hitting max excursion when getting hammer by the hot track. I noticed this only cuts in only at ear bleeding levels on my HRS120 sub (I still have a ear ache from trying to find where it was ahhahah).

    Putting on Matrix Reloaded car chase scene, and Titan AE as reference the resulting sound was absolutely sterile. So flat that there just wasn’t that pizzaz one looks for. So I spent some time playing some music and movies until I was happy with the adjusted curve to my ears. I just basically softened the amount of correction by a few dB in certain areas.

    Experience

    I am quite shocked at how good my sub is sounding. One thing that I have been trying to achieve in my home audio is that punch you feel in the chest when listening to a live concert through a good house PA. The DEQ2496 is making this happen with zeal! Through the entire care chase scene for Reloaded my couch was shaking, the pictures rattling and my house creaking. In fact the creaking was so bad that I had to back the sub off a bit in the really low Hz. In Music I finally feel like someone is knocking on my chest.

    The Next Step

    The next step is to move my PEQ curve over to DEQ which will also compensate for actual volume I am currently running
    I will also dynamically feedback destroy the room peaks while watching content to find the specific locations of any standing waves and then notch those out

    Pros

    Nice built quality for something so cheap
    Very quiet device really at the range of most people’s hearing (-90dB)
    61 band GEQ and 10 PEQs are great… but 10 DEQs is even better!
    Gives reproducible results in Auto-EQ
    Helps identify any high Hz or 60 AC Hz whining
    Has a great hard limiter
    Has a compressor/expander if its ever needed
    Can store different curves for use with different movies (I think this is a great feature)
    Allows me to monitor exactly how my sub is acting during playback
    At 96kHz sampling rate it should be fine for main speakers with anything less than DVD-A or SACD.
    Can RTA at the same time while while running other EQ's
    Much less fatiguing on my ears at high levels


    Cons

    Wish it would be available in –10dBV. And software would change levels on graphs along with this. But truth be told while watching a movie at 70-85dB listening position its running hot enough.
    Cannot autocopy GEQ over to PEQ
    Wish it could GEQ RTA down to 1/60 octave
    Difficult to update software through midi connection

    One question

    Is it normal that in the Matrix Reloaded car chase scene my couch is rumpling almost the whole time? Am I running my sub too hot? Was this what was intended by the authors?
    Anyone else have some comments about this device? I personally recommend it highly.

    James

    PS: My wife came home and her first comment: It sounds better than the theater… Wait till she watches Reloaded J
     
  2. Wayne A. Pflughaupt

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    Great review, James!

    I have to wonder why you chose the 2496 over the Feedback Destroyer. With it and a test disc of sine wave tones you could have accomplished the same thing for probably less than half the price – except the limiter, which doesn’t seem you don’t really need.

    I will admit though, that manually plotting sine waves on graph paper or an Excel program doesn’t have anything near the coolness factor of using an RTA. [​IMG]

    Is the compressor engaged? It would tend to push up the volume of lower levels signals.

    Regards,
    Wayne A. Pflughaupt
     
  3. Dennis XYZ

    Dennis XYZ Stunt Coordinator

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    Yep, you should use pink noise with an RTA. White noise has equal energy at each frequency. RTA and pink noise have a logarithmic energy distribution - each octave, or fraction of an octave, contains equal energy.

    PS - good call buying the DEQ. The RTA alone makes it worth the extra money over the BFD, not to mention all the other goodies you get for 'free.'

    PPS - there's a switch on the back to set 'consumer' voltage levels.
     
  4. JamesDB

    JamesDB Stunt Coordinator

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    Well maybe I am wrong on calling it white noise although at least in my work in pro sound we call it that. It definately did not use sin waves going up the scale slowly but the same fuzzy stuff that comes out of the Denon 3803 when leveling the channels. The RTA adjusted the sliders all at once. One advantage of this was that I could run the sub at higher volumes without stressing my coils as a sin wave would. This will also help me when moving over to the DEQ when I will have do dial in the parametric curves at different volume ranges.

    One thing that I found really interesting is that when you set the Denon to 80Hz crossover, the sub is still getting some signal even at the 160Hz range. You really have to set it to 40Hz in order to have 80Hz as the top signal moving through.

    The RTA is actually doing 1/6 octave (61 bars for 20-20kHz) alhough this doesn't seem to be adjustable on the GEQ at that level when auto-EQed(min 1/3octave discretion). Maybe I can Auto-EQ it and have it automatically put the data in the PEQ where definately it will be at least 1/6 octave discretion. I may be wrong in this and will try to confirm it more in the coming week. However I do know that if you use the Feedback Destroyer, with the mic you can find the standing waves at 1/60th octave. I will also experiment with this next week.

    One thing I wanted to say again is that this thing is really very quiet. I notice that it was even "complaining" about the denon, especially before the amp was warmed up. The Denon seems to put out some 14k-20kHz whine while colder in the -80- -70 level. Also at 96kHz sampling rate it is really very clean... you don't get that flanging sound you get at the lower rates. Now if it sampled at 192kHz like DVD-A it would be near perfect.

    What remains to be seen if how it will hold up in Cali heat on the long run. I know the DBX boxes then to do a bit better in that regard.

    As far as the switch is concerned, although it does lower the voltage input, I have not actually seen the software change on how low the level of the limiter, etc... can be set. Also it doesn't change the %100 peak level on the graphs on the LCD which it should. So what happens is that it still looks on the graphs like the signal being received is not as hot as it should be.

    James
     
  5. Wayne A. Pflughaupt

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    This is a pro audio unit. It’s supposed to be able to play all day outside in the blazing California sun and not skip a beat.

    Oh wait, we’re talking Behringer, aren’t we? [​IMG]

    Still, I can’t imagine that it would ever give any problems in an indoor environment. After all, home equipment like receivers are pretty light-duty compared to even budget pro audio gear, and they do just fine indoors.

    Regards,
    Wayne A. Pflughaupt
     
  6. Chu Gai

    Chu Gai Lead Actor

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    Do you think that part of the problem with disillusionment comes from the use of an equalizer, which deals with frequency domain issues, to erroneously correct problems in a room that exist in the time domain Wayne?
    Nice review James and those Behringer products are pretty nice and priced fairly well IMHO.
     
  7. JamesDB

    JamesDB Stunt Coordinator

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    I don't know Chu if I can say that EQing flat even with TEF correction ever made me happy. Of course I've never tried TEF in the home setting and maybe it would be different (given that the walls are much closer), my only experience with it is when calibrating very large arrays for contracts we did. Truth is that when I did do Time, Energy, Frequency, Reflection, Decay, Reverberation Time, 3D arrival etc. corrections for some live mid sized concerts years ago somehow it still didn't sound alive. We'd always go with some house curve to add color. I really believe, (and this is a personal opinion), that people have certain frequencies that they are internally more attuned to, and if missing somehow the music doesn't move them.

    Now I do know that Time and Energy decay based calibration is even more significant in the first 100ft from the stage, or in small rooms so you may be right especially when using 5.1 or 7.1 aimed in multiple directions.

    But I am interested in Wayne's opinion too since I am much less educated in home theater and I suspect that just as in medicine, you cannot treat a child like a small adult... very different rules apply in many cases.

    Well, I took a leap of faith with the Behringer and would say I am greatly pleased. I would not consider it truely pro class, the processing power is just not fast enough for immediate feedback reduction and truely transparent DEQ. It does not have software that is flexible enough in my opinion nor computer controlability. But at $300 I was surprised at just how good it is in terms of the actual lack of degradation in sound quality... of course if I were using Lexicon maybe I would not see it that way. And once I dialed in my own ear correction I was really much happier with the output than without it in the mix. In fact I would now consider it (or maybe the DBX) an essential buy.

    James
     
  8. JamesDB

    JamesDB Stunt Coordinator

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    Oh, I did want to mention that one pretty good indicator of a time delay problem is if the RTA indicates more than 6dB difference between 2 adjacent 1/3 octave readings.

    J
     
  9. BruceD

    BruceD Screenwriter

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    James,

    IIRC, acoustic models are mathematically different for acoustic spaces below 10k ft3 than for those used in large rooms like concert halls.

    So the methodologies used to tune large concert halls don't necessarily apply to our small HT rooms.

    But, I agree with you on the "essential" need for parametric EQ for the sub in most HTs.
     
  10. JamesDB

    JamesDB Stunt Coordinator

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    So the aside from using TEF or Smaart, are there other simpler methodologies or devices that are available for making corrections in the Time and Energy fields for HT? The more I think about it, this may be an even more complex problem in 7.1 in a home sized room than on large scale. I did hear that the DCX2964 had some limited time based correction available for the transducers.

    BTW, I did note a few things yesterday while going though the DBX Driverack PA online info. For one is cannot RTA realtime which the DEQ could. You have to move up to the 260 for that which is more expensive. The sampling rate is also a bit lower which was the main reason I chose the DEQ. As far a noise is concerned I am not sure. I've only seen it compared to the DCX which is analogue. Of course the PA does have some additional cool features but of less use to me in this case.

    James
     
  11. Chu Gai

    Chu Gai Lead Actor

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    I didn't say time delay rather time domain and along those lines, allow me to expand more upon what I meant and the question I posed to Wayne.
    Now don't think that I devalue the use of an equalizer or an RTA but I don't think that either of the two are the only approaches for dealing with room problems. In fact, they can be the wrong approach to certain problems and they ought to be supplemented or else one will get, as Wayne has said here and elsewhere, a room that measures flat and sounds terrible.

    An RTA is a time averaging device and given that the majority of room problems have to do with time domain issues, if one removes the information that's shorter than the combination of what the bandpass filter width is and the averaging that follows, then important information is lost and scrambled.

    Using the graphic equalizer in conjuction with the RTA to its utmost will give a scenario where the steady state transfer of the room is smooth (well relatively so) but gives the listener the false impression that room problems have been corrected. Were one to examine the RT60 times (Reverberation time necessary for the signal to decay to 60 dB below whatever its initial value was) we'd find it to be a mess with respect to frequency.

    Consider the following scenario.
    Assume you've got a speaker with a perfectly flat FR and you place it in your room. Now you sit down and listen to the speaker. The first thing that hits your ears is the direct sound of the speaker. At this point, there is no effect from the room. Now let us say that this room has a particular resonance at some given frequency. That resonance will affect what you hear since the sound wave from the speaker has to travel to wherever that resonance was formed thereby exciting it. This delayed reverberation then travels to your ear where you perceive it but after the direct sound.

    Let's say there was a peak of something like 10 or 15 dB at a particular frequency. You take your equalizer and notch out that much. So what happens? Well the direct sound is now notched out by that amount creating a 10 or 15 dB hole. That's what reaches your ears first. Then comes the reverberated sound. All looks well but as Wayne has mentioned, we've got a flat response and the sound sucks.

    In a general conclusion, if there's a problem with one's room, it makes more sense to fix the room and not try to correct it with an equalizer. Why ruin the characteristics of the speaker by creating holes in the FR with an equalizer? Alternatives such as the use of decent mics with sound cards and impulses might yield valuable information that can be used to correct the room with the use of two or three strategically placed bass traps and/or other sound treatment approaches.
     
  12. BruceD

    BruceD Screenwriter

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    Chu,

    One of the many reasons I prefer the MLS-based signal approach used by ETF5 with it's Energey Time Curves, Impulse Response Curves, RT60 calculation, and 3D frequency waterfall charts instead of an RTA.

    Can't say I've ever heard a room that improved enough with that small number of bass traps to make it worthwhile, and they are a challenge for the WAF. Parametric EQ can really help those rooms with bass peaks that simply drown out surrounding bass frequencies, probably >90% of most HT rooms.
     
  13. Chu Gai

    Chu Gai Lead Actor

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    The WAF is always a daunting problem and while I understand what you're getting at with the EQ, the issues that are a direct result of the room still exist, no?
     
  14. JamesDB

    JamesDB Stunt Coordinator

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    Hi Chu,

    I love reading your posts. I did understand what you were talking about because RT60 is something I wrestled with every day in my old career. Although I am an adamant supporter of trying to fix a room the reverberation decay rate... which is what I've actually been talking about when referring to when talking about Time and Energy. T & E is not that simple to fix by correcting the room though. The quagmire lies in the fact that for effective room correction one would have to not only have a good understanding of each of the frequency decays, but also how each of those frequencies is interacting with the materials in the room.
    I think correcting a room to evenly decay each frequency is an impossibility (short of anechoic which really doesn't meet the requirements for normal listening) because there are no materials of that nature available. Additionally plotting the interactions between the emissions of the 6 or 8 speakers and how the interact is difficult at best. Another thing is that reverberation decay rates are what we hear as depth in the music.. how far the subject is from another, back or front. Equalizing all the rates out might take away some of that field especially if it was not introduced using a reverb device.

    Ultimately what might be needed is a device that could understand the decay rates and produce a destructive wave to speed up slow decaying frequencies at each speaker node but of course only if it is not supposed to be in the music. Of course this assumes that the frequencies are bouncing back in some sort of cyclical fashion where the correction signal would not have to "catch up to it". Hmmm… maybe its witchcraft [​IMG]

    Sigh.. I wish my Denon had TEF built into it hahaha.
     
  15. BruceD

    BruceD Screenwriter

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    Yes, they still exist, but with EQ their destructive influence on many other bass frequencies is reduced, ultimately resulting in a sound quality that is improved (i.e. the masking effect of boomy bass --modal peaks-- is reduced).
     
  16. Chu Gai

    Chu Gai Lead Actor

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    I didn't want to make it come across like I was bashing you or your purchase, rather I wanted to bring something additional to the table. As Bruce made mention of, it likely will take more than two or three traps to take care of a problem fully but fully might be an overzealous and expensive approach. I like to find solutions or approaches that are especially cost effective. However, there might be enough of a taming and maybe that's the point some parametric approach might have it's greater utility without as much of a penalty. I'm rather a fan of Behringer products and enjoy that they're discounted well.

    Personally, I don't want a totally dead room and I agree that to fully correct a room might just take forever. Some of the approaches though seem to play better in rooms that are specifically dedicated and even basements that've been turned into HT setups. Somewhere in the house apart from the 1/2 bath there must be a place where a man can call it his castle (apologies to the ladies [​IMG])
    What are your thoughts on this link?
    http://koti.welho.com/msalone5/audio/
     
  17. JamesDB

    JamesDB Stunt Coordinator

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    Hey Chu,

    I've never seen you bash anyone, especially not for gear they bought or use (well maybe aside from voodoo powered speaker wires [​IMG] where I agree with you!) Certainly, I agree with you on the limitations of EQing and additionally appreciate the dialogue on this subject.

    Tell you the truth that article is what made me leave the industry for programming because of my perfectionistic analness. At least there I now have a bit more measure of control over how it acts... although not always ie. threads.

    I like the article, although I've never used that particular software before (I am now very curious about it especially the CARA which seems so simple to interpret). Are you familiar with the TEF analyser? One ongoing frustration I have, and I am nowhere close to correcting it with my cash level is that I cannot seem to optimize the sound for multiple seats. Sure on seat is still decent right now, but all the seats?... dang this is what heaven will be. 4 dimensional accoustical correction.

    My wife has been buying paintings for the wall, so that seems to be helping some. But I wish I could build an addon to my house with no parallel walls and gobs of accoustical treatment. I would like seating no closer to the back or side walls than 30% of the room length to improve center channel intelligability. Also 4 subs placed front, back, leftside/rightside to give a flatter curve etc.etc... A room just for HT, is that too much to ask for? [​IMG]

    But I was wondering. Do you (or anyone else please chime in) know of some good software available for finding the best placement for speakers? I was looking for something where maybe it could take a few measurements at different seating positions for maybe a few speaker positions and then it would extrapolate out a good placement without me having to go through umpteen combinations. If it would allow me to set up say 4 mics in the different places on my couches, and then real time show me the decay rates as well as frequency curves while I move the speakers around that would be so useful.
    Regards,
    J
     
  18. JamesDB

    JamesDB Stunt Coordinator

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    BTW, How good is CARA? Has anyone tried it?
     
  19. Chu Gai

    Chu Gai Lead Actor

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    I think that to correct for all seats or stand a good chance of doing so, you're going to have to get into room treatments as any software based approach could only give a nearly optimum solution for only one point in space. I haven't tried the CARA and that link was one that I had laying around my favorites area that I'd forgotten about.
    I'd say you might need a second job to pay for all those things James or at least some investment tips from Martha and Hillary [​IMG]
    That's damned nice of your wife to be taking a positive interest with the paintings. Have you also considered something more substantial like either carpet hangings, larger acoustic panels that can have something decorative over them, or even bookcases at the reflection points?
     
  20. BruceD

    BruceD Screenwriter

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    Chu,

    Has the guy in the article you provided the link for ever updated his measurements with something better than 1/3 octave steps?

    I find that 1/3 octave measurement steps are just too coarse for finding bass modal peaks, a minimum of 1/6 octave or even 1/12 octave measurement steps is preferred.
     

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