Room EQ with Behringer DEQ2496 and 4333's

[kevf]

I'm playing with my newly acquired toy, the Behringer Ultracurve Pro DEQ2496, and trying to EQ my listening room (24"x30" basement).

Initially, I measured a huge peak of 15db on my left channel around 16kHz. This is with the speakers toe'ed in to the listening position.

I tried moving the speakers around and it quickly became obvious that even a few inches movement of speaker make huge (and I mean HUGE) differences on the RTA. Getting rid of the toe in seems to have flattened the above mentioned peak somewhat.

So it looks like I have some work ahead trying different speaker placements.

In the meantime, I have a couple of questions:
1. I've built "cab extensions" that the 4333's sit on so that the 2405 is now at ear level. I'm now second guessing this move as I have a feeling the peak mentioned above is exaggerated (if not caused) by having the HF at ear level. Are the 4333's meant to sit that high?

2.The DEQ2496 has an Auto EQ feature where it calculates the EQ required to flatten the room. It sends pink noise to BOTH channels and then it EQ the LEFT. Then it sends pink noise, again to BOTH channel and EQ the right. I'm not certain this makes sense as I would think its better to send pink noise through LEFT only when it EQ the LEFT (and pink noise to RIGHT only when it EQ the right). What is the proper procedure to EQ a room?

Thanks guys
Kevin

BTW, my problem was first mentioned in this thread, but I didn't want to highjack that thread anymore
http://audioheritage.org/vbulletin/s...ead.php?t=6666

[Robh3606]

Hello, Kevin

1. I've built "cab extensions" that the 4333's sit on so that the 2405 is now at ear level. I'm now second guessing this move as I have a feeling the peak mentioned above is exaggerated (if not caused) by having the HF at ear level. Are the 4333's meant to sit that high?

I did the same things on my 4344 clones to get the 2405 up at ear level. The 2405 has a very narrow verticle patern above 15k so you need to have them up there. It also helps to get those 15's up off the floor a bit. The bottom line is what works best overall. If you have issues with the lowend from being up then you have to decide which works best for you in your room. With me up on short stands work well on both ends so it's a no brainer.

"I'm not certain this makes sense as I would think its better to send pink noise through LEFT only when it EQ the LEFT (and pink noise to RIGHT only when it EQ the right). What is the proper procedure to EQ a room?'

Get a test disk like the Delos HT disk that has the requiste L/R bands and run in RTA mode to see what you get. I run left and right, check the match betweeen the speakers through the midrange + say 200Hz up to say 8K and then look at the overall balance with both channels. That's what I do and It has worked well. Watch any boost in the auto EQ. I use cut only EQ's. Remember 6dB Equals 4X the power and reduces your headroom accordingly.

Rob

[Zilch]

As context, my UltraCurve firmware is V1.2B.

I raised the AutoEQ issue when I first started using it. Just tried it again to confirm:

DEQ2496 has two operating modes, "Stereo Link" and "Dual Mono" selected via the "Utility" menu. In "Stereo Link," left and right channels are handled simultaneously, including AutoEQ. Only one GEQ curve is generated, and that is applied to both channels. You've got to be very careful about the placement and aiming of the microphone to get a good result; phase cancellations from the two speakers playing simultaneously will mess it up.

Just watch the RTA while you move the mic slightly playing pink noise. You must find the "sweet spot" between the acoustic centers for it to work well, and having the mic centered some distance (e.g., the listening position) in front of the speakers makes the task easier. I assume you know how to turn the pink noise on and set its level from the I/O menu. Took me a while to find that.

In "Dual Mono" mode, as you describe, separate GEQ curves are generated for Left vs. Right channels. You choose which one AEQ is working on from page 2 when you're setting up each run. You have to turn off the other channel manually. I do it by unplugging the opposite output cable on the back of the unit.

I just tried it again allowing both channels to play during the process. As logic would dictate, it generates bogus results results that way. I've been meaning to track this down with Behringer, but never found the time to do it. For a while, I thought it was smart enough to know what noise was being sent to each channel at any point in time, and used that to sort out the data. It certainly didn't work that way here tonight.

For this, I also find the "sweet spot" with both channels playing and then leave the mic stationary while AEQ does its thing on each individually. It can take as long as 10 minutes for each AEQ process to go to completion in the "slow" mode. I start it on "fast" and switch it sucessively to "mid" and "slow" as the process progresses. Then, I get out of the sound field for the duration, watching for the "action" to stop on page 3 before hitting "Done." Afterwards, you can edit the two curves in GEQ.

For me, it's primarily a research tool. I've got a bunch of different curves for different setups saved in the memory. I forget what they're for soon after saving them. Seems no two setups are ever the same here....

[Mike Caldwell]

Hello
In the end I would your ears to make the final EQ adjustments. No microphone and simple RTA is ever going to "hear" the same as your ears do, there are simply too many variables involved in the process. You have two ears/microphones built into the sides of your head spaced apart by about 6 inches or so. The time difference of a sound arriving at one ear and the other is what gives the ability to hear depth and width or the imaging of sound and the precived frequency response. One single microphone simply can not do all of that. There are a few high end measurement systems using multiple mics that can do a fairly close job of telling us what our ears are hearing. Many times in the pro sound world someone will set their system up using SMART or similar product and them do the final tweak by ear and saying test 1 2 into a microphone.
Like was mentioned before if using the auto EQ watch out for excessive boost being applied in it's attempt to get a perfectly flat response, primalry in the low end if it tries to make a speaker flat to 20hz that is only able to go down to 45hz (or what ever frequency) with out blowing up!

My thoughts
Mike Caldwell

[kevf]

"You have to turn off the other channel manually. I do it by unplugging the opposite output cable on the back of the unit."

I just find it very odd that I have resort to unplugging one channel manually when EQ'ing the other channel. I did email Behringer and they told me that its not a bug, and that's how its suppose to work - pink noise will be generated for BOTH channels while the unit EQ one channel. Being new at this, I thought maybe someone in the group will confirm whether this is the standard procedure. From the responses so far, it doesn't sound like it.

As far as "trusting my ears", yes, I plan to eventually fine tune it by ear and not trust the AutoEQ completely. But with different recordings/time of day/mood/bad memory etc, I find it really hard to "trust my ears" a lot of times!! What I'm finding is that this unit is a great help in identifying problem areas. And its a lot of fun to play with all those functions .

Kevin

[boputnam]

You have to turn off the other channel manually. I do it by unplugging the opposite output cable on the back of the unit.

Some days, you just gotta LOVE Zilch!! Took the words right outa my fingers.

I do the same thing at FOH - although there is no Behringer gear anywhere within sharpshooter distance.

Just fade out one channel, point the mic, adjust. Repeat for other side.

[speakerdave]

Not that I really know anything about it, but it seems to me pink noise in two channels is better because the speakers are never played singly. Both speakers create the sound field in the room, and the interactions between the speakers are part of it as are the individual characteristics of the speakers and their locations. Pink noise in one speaker at a time will correct one speaker in the room. Using the two speaker method the first correction is probably over-correction, but it includes a mirror image of the anomalies of the other speaker and its position so that when that is corrected the room modes of both speakers in the whole sound field are addressed. In each subsequent change of channels the process is refined.

David

[stevem]

As far as "trusting my ears", yes, I plan to eventually fine tune it by ear and not trust the AutoEQ completely. But with different recordings/time of day/mood/bad memory etc, I find it really hard to "trust my ears" a lot of times!! What I'm finding is that this unit is a great help in identifying problem areas. And its a lot of fun to play with all those functions .

Kevin

I get the best results when both the measurements and my ears tend to agree, so I always look for a correlation between the two.

[boputnam]

...it seems to me pink noise in two channels is better because the speakers are never played singly. Both speakers create the sound field in the room, and the interactions between the speakers are part of it as are the individual characteristics of the speakers and their locations.

True. But each individual channel / speaker cabinet / stack will likely be positioned in a quasi unique position creating it's own unique acoustical reaction with the room / setting - particularly if one is tucked into a corner and the other is not.

I merely reported "industry convention" wherein each channel is operated singly and it's unique room affects analyzed. That is the point of having a two-channel EQ. Once each side is done, adjusting to "taste" is NOP.

Regardless, do it however floats your boat!

[Robh3606]

"I get the best results when both the measurements and my ears tend to agree, so I always look for a correlation between the two."

Hello Steve

Great point you use both and they should agree.

Hello Speakerdave

"Not that I really know anything about it, but it seems to me pink noise in two channels is better because the speakers are never played singly. Both speakers create the sound field in the room, and the interactions between the speakers are part of it as are the individual characteristics of the speakers and their locations."

You really need to do both. You look at each on its own. Get them dialed in and compare the individual curves to match them as best you can. Then look at the summed curve with both. You need to "see" what each speaker is doing as well as the summed response. Without looking at each individual you have peaks or nulls unique to each that need adjustments that are unique for each channel. My speakers are not symetrical in my room so they require different curves to flatten them out.

The ear may be the final tool but you can spend weeks chassing your tail without measurement equipment. It saves you lots of time and typically there is good corelation between what you measure and what you hear as Steve pointed out. There is also a large window that sounds good. Without measurement equipment you can spend lots of time doing set-ups by ear and still not get it right where it all comes together. When you do get it "right" you will know it. The balance will be great, you won't be running for the EQ with every recording, your imaging will be good and you will just find yourself listening to the music not the speakers.

Rob

[Mike Caldwell]

I do the same thing at FOH - although there is no Behringer gear anywhere within sharpshooter distance.

I like to keep Behringer gear at such a distance that a GPS guided cruise missile would not be able to hit it, that way there is no chance of contamination or cross breeding with the rest of my equipment!

Mike Caldwell

[boputnam]

I like to keep Behringer gear at such a distance that a GPS guided cruise missile would not be able to hit it, that way there is no chance of contamination or cross breeding with the rest of my equipment!

Me too. And I tried a few just to make sure there was no value to be found.

[johnaec]

While maybe not top-of-the-line, it seems like most of Behringer's problems stem from reliability issues. They may hold up somewhat better in a home environment. I'm using DBX stuff myself, ('no experience with Behringer, other than what I've read in sound forums, etc...).

John

[Mike Caldwell]

When mixing a friends band on their PA it sounded better when the Behringer comp that was inserted on the vocal sub group was pulled! Normally I like a little compression on the vocals but in this case it was better without, the Behringer sucked the life out of vocal the instant it started doing any amount of compression. He has now since upgraded to a Drawmer comp. Reliability is a big concern with any of the "B" equipment. The sound quality or lack of is there, get past the blink lights and the wiz bang features and listen close and then remove the unit from the signal path, not just hitting the bypass switch but hardwire past the unit. Hitting bypass in most cases still leaves a fair amout of active components in the signal path. The lack of reliablity and sound quality comes from using the absolute cheapest components available. Many of the Behringer products are design rip offs of quality equipment and they have the law suites to prove it.
Every time you pass signal through a piece of equipment it gets degraded reguardless of the quality of the equipment, good well designed equipment has far less degragation than a piece of well.... not so good equipment. The degragation adds up with every pass through a piece of processing equipment.

Mike Caldwell

[boputnam]

1) it sounded better when the Behringer comp that was inserted on the vocal sub group was pulled!
2) the Behringer sucked the life out of (the) vocal the instant it started doing any amount of compression.
3) The lack of reliablity and sound quality comes from using the absolute cheapest components available. Many of the Behringer products are design rip offs of quality equipment and they have the law suits to prove it.
4) Every time you pass signal through a piece of equipment it gets degraded regaurdless of the quality of the equipment... The degragation adds up with every pass through a piece of processing equipment.

It's ALL about the filters, man. If one really listens, you will know. My wifey - and a few other friends - who claim to "not know anything" about pro audio, can hear the difference. They maybe cannot describe what they hear, but they know what works and what grates. They know, Behringer sucks.