Thoughts on using the Behringer DEQ2496 for room correction

[Mike Anderson]

I've been experimenting with this a fair amount, and I think I finally have it down. I have to say, it is making a huge difference in my sound, and for the better. I really like this thing now that I've learned how to use it.

However, the manual sucks. At some point, I'm going to type out step by step instructions, but here are some general tips for now. Note that this is just what I do; other people with different components, rooms, tastes, etc. may find something else works better.

First, here's my setup: I'm taking a digital signal out of the optical Toslink output from my Squeezebox (essentially equivalent to a CD transport), and running it into the Behringer's optical input. I then take the digital Toslink optical out from the Behringer, and run it into the digital optical input of a Benchmark DAC1. I take the balanced XLR analog outs from the DAC1 and run it into my amp (Pathos Logos driving Magnepan 1.6qr speakers). So all the processing is done in the digital domain.

1) I plugged the ECM8000 microphone into the RTA input, and place the microphone right where my head would be in the normal listening spot. I measured the distances from the tip of the mic to each of the speakers to make sure the mic was equidistant. The mic was pointed straight ahead to the spot directly between the speakers.

2) This is crucial: I put the Behringer in dual mono mode, NOT stereo link; this lets you EQ each speaker independently. When I first got the thing, I didn't do this, and was getting some pretty crazy results. To do this, press the Utility button, scroll down to Channel Mode and change it to Dual Mono. Don't forget to press the B button to accept the change.

3) Now hit the I/O button. Make sure on page 1 (called "Select Input") that the input is set on "Main In." I think this is the only way to EQ each speaker independently. I initially thought this had to be set to Pink Noise, but in fact you'll get pink noise automatically when you go into Auto EQ mode.

4) Still in I/O mode, on Page 2 (called "Aux/Dig. Out"), select GEQ-PEQ. This will make sure the EQ'd sound is coming out of the Behringer.

5) On Page 3 ("Select RTA Input"), select RTA/Mic.

6) Now press the GEQ button. Flatten the curve, putting all frequencies on 0db. Make sure you do this for both channels, pressing the A button to switch between them.

7) Make sure you've got the proper input sensitivity and phantom power for the microphone you're using. If you're using the ECM8000, I think the default settings should have it covered.

8) Turn up your amp volume fairly loud, and warn your wife that a jet plane is about to land in the living room. Make sure nobody is walking around, or otherwise making noise.

9) Hit the RTA button, and cycle through so that the Auto EQ label shows up next to the B button. Adjust the Max and Range levels so that you'll get a good window on the frequency read out. You want something narrow enough so that you can easily see differences between the frequency levels, but wide enough so that you can see all the peaks.

10) Start the AutoEQ process. Note that you'll have to do this twice, once for each speaker. The pink noise should only be coming out of one speaker at a time. If for some reason noise is coming out of both, you need to change what you're doing.

I like to have "Room Correction" on, which "tilts" the target frequency spectrum from flat to slightly weighted in favor of the low freqs. Just sounds better to me.

I also didn't do any automatic correction below 100Hz. Instead, I manually adjusted them later, after the AutoEQ had flattened everything else.

I also put the noise level at about -1db, so as to avoid clipping. Keep an eye on the level meter and make sure there's no red flashing. If there is, lower the noise level; if there isn't, raise the noise level until there is, then back off slightly.

Note that during the AutoEQ process you can toggle between pages to compare the RTA readout with the adjustments the Behringer is automatically making to the GEQ. You can also switch between "Fast", "Med" and "Slow" to determine how fast it reacts. I like to start it at Fast, then change it to Med after a minute, then to Slow for a minute or so.

I set the Delta Max and Span to their maximum values, and didn't have any problems. Others may have to narrow these parameters, e.g. if you've got a big problem with your room or setup somehow.

At some point, after a few minutes, it should get to the point where the ongoing adjustments are fairly modest, and you can stop the AutoEQ then. Again, note that you have to do this twice, once for each speaker.

After you've run the AutoEQ, go back to the I/O page and change the input to Pink Noise. Noise should be coming out of BOTH speakers now. Then go back to the RTA, and look at the spectrum. You may notice -- as I did -- that it is no longer flat, now that you have both speakers going. I had a dip right around 12khz. I went back into GEQ, and adjusted the EQ (for each channel -- so you have to switch between Left and Right, making the same changes in each), then toggled back to the RTA, back and forth, until it was fairly flat.

Next, I manually adjusted the GEQ below 100Hz to get something fairly flat. (My speakers roll off below 40Hz, so naturally I didn't try to fix that range.) Note that again, you have to use the GEQ on both channels.

Finally, change the input back into your music input, and do some listening. Season to taste; I generally like a little more bass than you get out of a perfectly flat response.

That's it! Practice and experiment with the thing, and eventually it will have your setup sounding *very* sweet. The improvement is quite dramatic, in my case.

It's definitely a good way to spend a few hundred bucks. Compared to switching out interconnects, tubes, etc, where the differences are subtle at best, this is a REALLY noticeable difference. You can hit a button to bypass it all if you like, and compare it to the unprocessed signal. BIG difference.

[Mike Anderson]

Here's a shot of the DEQ correction for the right channel:



Here's the correction for the left channel -- it's quite different than the right channel in the bass frequencies, but ended up being identical in the high frequencies:



And here's the RTA at work (on music, not pink noise):

[Feanor]

I've been experimenting with this a fair amount, and I think I finally have it down. I have to say, it is making a huge difference in my sound, and for the better. I really like this thing now that I've learned how to use it.
....

It's definitely a good way to spend a few hundred bucks. Compared to switching out interconnects, tubes, etc, where the differences are subtle at best, this is a REALLY noticeable difference. You can hit a button to bypass it all if you like, and compare it to the unprocessed signal. BIG difference.

Since I plan to get this Behringer unit one of these days you suggestions and observations are highly relevant to me.

It's not surprising to me -- at least -- to hear you say that this equalization makes for a really big improvement versus a lot of equipment swapping and other tweaks that do less but cost a lot more. I take it from you lack of comment that you hear no significant downside to the Behringer: loss of resolution, air, dynamics, whatever?

Purists can appalled if they like, but one wonders how many billions of dollars audio enthusiasts might have be saved collectively if high quality equalization were tried instead of speaker upgrading or swapping

[Mike Anderson]

I can't detect any loss of dynamics, resolution, or degradation of any sort. If there is any, it is very, very minor, and my ears cannot detect it.

I don't claim to have "golden ears" though, in fact I have a fair amount of tinnitus in one ear that has caused nonnegligible loss of hearing in the high frequency range.

Also keep in mind that I'm using it entirely in the digital domain, and hence doing no AD or DA conversion. I can't speak to what the results of that might be.

[Feanor]

I can't detect any loss of dynamics, resolution, or degradation of any sort. If there is any, it is very, very minor, and my ears cannot detect it.

I don't claim to have "golden ears" though, in fact I have a fair amount of tinnitus in one ear that has caused nonneglible loss of hearing in the high frequency range.

Also keep in mind that I'm using it entirely in the digital domain, and hence doing no AD or DA conversion. I can't speak to what the results of that might be.

I'm over 60 and can't hear anything above 10kHz, plus I have a bit of tinnitus in both ears too.

Thanks again: a pretty good endorsement for the DEQ2496!

[Mike Anderson]

A couple more points:

After you've run the AutoEQ, go back to the I/O page and change the input to Pink Noise. Noise should be coming out of BOTH speakers now. Then go back to the RTA, and look at the spectrum. You may notice -- as I did -- that it is no longer flat, now that you have both speakers going. I had a dip right around 12khz. I went back into GEQ, and adjusted the EQ (for each channel -- so you have to switch between Left and Right, making the same changes in each), then toggled back to the RTA, back and forth, until it was fairly flat.

At this point you should be running the RTA in "Average" mode, which averages out the peaks over time. You should reset it each time you change the GEQ, cycling through from fast to mid to slow and back to average to get a new reading.

Also, one other thing that's very important: After you've set the EQ, you need to make sure your output signal isn't clipping, because you may be adding a substantial amount of gain to the signal.

So go to the Meter page, and switch Source to Output. While you're playing music that you know has a very loud signal, check the outside meters to see if they're clipping at all. (You probably want to leave this on for a long period of time, so that you end up capturing the hottest peaks you can.)

If you're clipping, go to the Utility menu, and set Gain offset to -5db or thereabouts. Then go back to the Meter page and monitor it again for a while. Go back and forth until you are fairly sure you're not clipping, while not taking too much off your signal.

For my EQ, I find -5db to be about perfect. I can play several hours of hot signal, and get peaks at around -0.1db below clipping. Ideally, this is where you want it, assuming you don't have to lower it even more to accommodate your preamp inputs.

I've got my setup sounding really, really good now.

Of course it's a bit of a pain, since I'm still working with speaker arrangement, and you have to reset the thing every time you move the speakers, requiring a good 10 min blast of loud pink noise -- but I'm definitely getting it dialed in.

It's true that it doesn't sound perfect everywhere in the room, but right in the listening spot, it's totally sweet!

[Feanor]

A couple more points:
...
Also, one other thing that's very important: After you've set the EQ, you need to make sure your output signal isn't clipping, because you may be adding a substantial amount of gain to the signal.
...
I've got my setup sounding really, really good now.

Of course it's a bit of a pain, since I'm still working with speaker arrangement, and you have to reset the thing every time you move the speakers, requiring a good 10 min blast of loud pink noise -- but I'm definitely getting it dialed in.
...

Thanks for these additional comments.

I doubt that anything could ever produce perfect balance everywhere in the room -- early reflections are bound to differ at different listening location. But that's not reason not to use the equalizer.

For my own use of a much less precise equalizer, I believe it is one of the most useful and cost effective ways to improve your sound.

[rneiva]

Mike, thank you for your post. I must confess that I bought my DEQ last week and and went through the same painfull process. The manual stinks. I am an electronics engineer and I've speciallized in Digital Signal Processing which is what DEQ is all about. Even though I have a deep technicall backgroung in this field, one must read several times the, let's call it, manual in order to start to grasp how to do things. After reading your post I will follow it because you are somewhat ahead in the process.

Behringer should do an addenda (and I would even pay for it) on how to do a Room Correction, how to improve your system etc.

I have a doubt. I have the DEQ inserted between the pre and the power. My CEC CD reader has an AES digital output which I fed to the digital AES input. I it was loud, very loud and I could not find a way to control de volume of the signal fed to the power. Is this possible ?

Thank you and regards

[E-Stat]

Purists can appalled if they like, but one wonders how many billions of dollars audio enthusiasts might have be saved collectively if high quality equalization were tried instead of speaker upgrading or swapping

As Mike mentioned, this unit works solely in the digital domain. The vast majority of equalizers, however, use conventional op amp based analog gain stages that add their own distortion components. I use a Behringer third octave EQ (analog) between the LFE output of my HT receiver and the powered subs to flatten the low end response. Works great for that purpose.

EQ can only fix frequency errors. No collection of any EQs on the planet digital or otherwise can magically transform the performance of my Advent or Polk speakers into that of the electrostats.

rw

[rneiva]

I understand that all the processing is in the digital domain. Even so, one can control the volume in this domain. Shift right is -3 db. And the DEQ has a DAC so I was wondering if there was any way to control the volume output so I could insert the signal directly from the CD reader with going through the pre.

[PeeBee]

I have experimented with this piece of equipment, but ultimately it lost the transparency for me, I'm no purist, I bought it new with mic and sold months later at a loss, it definately is worth a listen, but will not suit every system, my room doesn't need much correction anyway, but i lost transparency and dynamics, yeah could be made to have bigger soundstage etc, and sound was different to my normal, but was different, NOT better, be careful when you hear differences in kit, as often they are just that, all to often folks get caught up and discover a different sound, assume it,s better, only to later on realise they are unhappy with change, and then blame something else.

I know of one or two who did find the deq made their system sound better for them, and at £250ukp it's cheaper than a lot of cables, and does so much more, glad it's working for ya dood.

[PeeBee]

I understand that all the processing is in the digital domain. Even so, one can control the volume in this domain. Shift right is -3 db. And the DEQ has a DAC so I was wondering if there was any way to control the volume output so I could insert the signal directly from the CD reader with going through the pre.

IIRC you can't do this, at least not easily, and not with same control or finesse as a pre, it makes a good cheap dac for TV box, dvd players etc, although it has 3 inputs you'd need to use a different connection for each device, XLR analogue, optical and aes/ebu xlr digital.

[vlada]

Mike,
can you tell us something about soundstaging properties of DEQ2496 and its settings ? If I understand the matter correctly, these "targeting curves" that you apply to freq response essentially re-arrange the 3D staging characteristics, e.g. - when you lower the "presence range" (2-5 Khz) slightly, you get somewhat more depth of stage, and vice cersa ?
I believe that Tact (Lyngdorf) room correction systems do something essentially similar...?

[Mike Anderson]

I haven't noticed any big change in soundstage or transparency, but then I haven't systematically analyzed it either.

[Mike Anderson]

IIRC you can't do this, at least not easily, and not with same control or finesse as a pre,

I think you can do it, but you're right, it's not really designed for that. You can change the output volume, but you're going to have to take an awful lot off the top if you're not going through a preamp.

If I have a hot signal, I'll take off about 5db to avoid clipping (because the EQ tends to boost the signal), and I don't notice any dramatic difference in sound quality when I do it -- but I wouldn't want to take off 40db all the time.

Hypothetically it could work OK, but it isn't a very graceful solution.

[PeeBee]

I haven't noticed any big change in soundstage or transparency, but then I haven't systematically analyzed it either.

Transparency was biggest change, Transients had less impact, decay was not so prominent, all for me, loss of bass impact too (wifey noticed this first) when running with deq in system but switched out, there was no difference in transparency, than when it was on and EQ'ing, and in this case the EQ was better, however disconnected the difference was quite marked, the CDP on it's own was much more coherent, much more transparent, in whole more real, I gave this kit 3 weeks in my system, used it as a dac for another couple of weeks, and then sold it on, I'm not knocking it, it's worth a try, but I reckon thers a level where it does more harm than good, and the sound it produces is different, maybe more to your taste, but is not necessarily better?

[Mike Anderson]

^^^ Were you using the Behringer entirely in the digital domain?

I feed a digital signal into the DEQ, process it, and take a digital signal out. No conversion to analog.

If you're using it partly as a DAC, I can see how your results would be different.

My DAC is a Benchmark DAC1, which is undoubtedly of much higher quality than the Behringer's.

[PeeBee]

Yeah mike, I was using it as a dac too no seperate dac for me, and the dac in my cdp is connected via I2S bus rather than the norm, I'm not knocking it a fine bit of kit, and as a dac it's certainly a lot better than a lot of "hifi" dacs, and it costs realtively little, and has all the adjustment built in too.

[Hipper]

Thanks, Mike for the guidance. I've followed it to the letter but after pressing 'StartAuto EQ' and the ambient noise is measured, the Pink noise is not loud enough for the Behringer's satisfaction (and it is very loud to my ears) so the Auto EQ stops.

What appears to be happening is that the ambient noise recorded by the Behringer is too loud. The level meter to the left of the spectrum on page 2 of the AEQ menu reaches half to three quarters high during ambient noise measurements. I've also noticed that when there is no sound from the speakers, and the microphone (the ECM 8000) is on with the RTA spectrum showing, there is noise below 100Hz, which increases with each frequency decrease (i.e. 20Hz is louder than 25 Hz etc.). When the microphone is disconnected the readings die away.

Any idea what is going on here? Could it be a fault with the microphone or connecting cable perhaps?

I should add that my set up has the Behringer 2496 connected between my CD Transport and DAC using XLR cables.

Michael.

[Mike Anderson]

^^^ The pink noise should be quite loud -- loud enough to drown out the ambient noise by far.

There's a way to increase the level of the noise. Try this: Press the I/O button, and turn the big knob until "Pink Noise" is highlighted. On the lower-right-hand side of the screen, you'll see "Noise-Gain". Turn the small, lower knob on the right up until it gets to 0.0 dB or thereabouts. Then go re-try the Auto-EQ. That should do it.

I should have put that into my instructions above, now that I think about it. The thing is, once that parameter is set, you forget about it, so I forgot to include it after several iterations of cycling through the process.

[Hipper]

Thanks Mike. I knew about the noise gain though! In fact it can also be controlled from pages 2 and 3 of Auto EQ.

The Pink Noise really is loud. Literally painfully loud. I can't bare it. The only time I got any Auto EQ response was when I placed the mic about one foot from a speaker.

What I don't understand is, what is this ambient noise the mic is picking up? I have double glazing; the door is closed; I can't hear much sound. I accept there will be some low rumble from traffic (I live about 20 metres from a busy road) but it doesn't intrude on my listening. Furthermore, the ambient noise picked up by the mic seems to be 100Hz and below, and these frequencies are ones I'm not measuring, following the guidance in the Behringer manual.

[Mike Anderson]

What kind of micrphone are you using?

You may have to adjust the sensitivity level of the mic. I'm not at home at the moment, will have a look later this evening.

[Mike Anderson]

Hipper,

Check Section 3.11 on p.16 of your manual:

"Select MIC LEVEL as input sensitivity on RTA/MIC. If you are using a condenser mic, you need to acitivate phantom power (MIC LEVE + 15 V).

On RTA/MIC MIC LEVEL, adjust the sensitivity of the mic you are connecting. If you are using the Behringer ECM3000, this value is -37 dBV/Pa."

Let me know if this works, otherwise we can check something else.

[Hipper]

ECM 8000. Mic set up correctly according to the manual: phantom power +15V and sensitivity -37 dBV/Pa.

In fact I was wondering if I should tamper with the sensitivity setting to see what that does. The spec for the mic says 'sensitivity -60dB'.

It also occurred to me to try to see what the ambient noise readings are in the early morning (0200 say) when the traffic is almost non existent.

[Mike Anderson]

Are you holding the mic with your hand? If so, the sound of your hand rubbing against the mic could be causing extra low frequency noise.

I suppose it's possible there's a problem with your mic or the cord too.

Other than that, I'm out of ideas.