# Using the DEQ2496 for a sub-peak limiter?



## Drudge (Sep 1, 2008)

My subwoofer tends to make a lot of ruckus on certain bass demanding scenes in movies and I have been using the sub-peak limiter function on my processor to prevent the sub from making the stained noises.I'm going to be jumping into blu-ray soon and I'm going to be using the analog outputs of the player through the analog bypass of the processor and the limiter is bypassed,so I want to see if I can use the limiter function in the Behringer DEQ to perform the same function.

Does anyone know how you would set the attack and release controls on it to an equivalent of the sub-peak limiter in the processor?If I don't set the values properly I know that I can cause a pumping effect or not limit the bass quickly enough.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Yes, if the DEQ has a limiter, it can perform the same function as your processor. Isn't there instructions on how to use it in the DEQ manual? If not check dbx's website and look up a manual for one of their compressor/limiters. That should tell you what you need to know.

Regards,
Wayne


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## Andysu (May 8, 2008)

Well I only have one DCX2496 for the LCR fronts. I can unplug say the centre channel and use the LFE.1 on the DCX2496 and run a battery of tests to find a suitable setting.

Not right now its 05:55am maybe later in the day.

Do you have any films in mind?

Also my AVR has bass peak manager part of the THX circuitry that is sometimes used. At present its set in bypass mode the LFE.1 plays fine just as long its not been played at silly +db over the top levels where it drowns out the bass on LCRS.:hsd:

There is way of improving the softer LFE.1 moments while relaxing the louder moments.


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## Drudge (Sep 1, 2008)

The manual isn't very specific.I've read up on compressor/limiters and it seems that it depends on the quality of the units and the specific settings used,but no real specifics that I can find.:scratch:

The movie I was using to set my THX sub-peak limiter with was the submarine pass by seen in K-19 The Widow Maker.It starts at chapter 5, time 37:00 minutes,that's were my sub just starts to give up the ghost.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Drudge said:


> The manual isn't very specific.I've read up on compressor/limiters and it seems that it depends on the quality of the units and the specific settings used,but no real specifics that I can find.:scratch:


That's because compressors/limiters can be used for all sorts of things, from "shoring up" low-level signals to "fattening up" guitars or drums for the purposes of recording, etc. What you're looking for is settings pertaining to preventing clipping or speaker damage in a sound system


These manuals might be helpful to give a better understanding of how the controls work:

ftp://ftp.dbxpro.com/pub/PDFs/Manuals/English/dbx166XLManualA2.pdf
http://www.ashly.com/Resources/Documents/Manual/clx52-manual-n.pdf

Pg. 8 of the dbx manual gives some settings that might be a good start.

I’m no expert with limiters, but based on the basic controls found on the face of the Ashly (see the picture in its manual), which are more common for compressors than what dbx uses, I’d suggest first paying attention to the compressor’s gain control, which adjusts the signals coming into the compressor. Your incoming signals, coming from a home theater receiver, are going to be much lower than what’s typical in a pro sound system. If the compressor doesn’t register a healthy signal level, then it will not kick in. So increase the gain until you get a healthy reading on the input meter.

The Threshold setting determines at what point gain reduction begins. If you aren’t able to get a hot enough signal via a compressor-specific gain control, then you can probably compensate for that with a severe threshold setting - i.e., force the point where gain reduction begins down so far that it “reaches” low signals.

Not entirely sure how to set the Ratio control, but you’ll set the Release control by ear. Basically, if it’s too severe you’ll be able to tell that limiting is still occurring after the peak signal has passed. I.e., it’ll be “holding” and squashing lower-level signals that are present immediately after the peak signal hits. Audibly speaking, it sounds like a “lingering” effect.

A good way to get your adjustments in place is to use a pink noise signal, and run up your receiver’s volume up to the point that your sub starts making rude noises, then back down a smidge and start adjustments from there. That should be your 0 dB input level reference. (You might want to disconnect your other speakers during this exercise.)

Ultimately, you want settings that get you something like this, using the compressor’s metering as a guideline: When the input level meter hits 0 dB (which you should have calibrated as the threshold point where limiting begins), the gain reduction meter should be lighting 2-4 dB. As you drive the input meter to readings above 0 dB with your receiver’s volume control, the gain reduction meter readings should also increase, but perceived volume levels should remain constant. 

An example of a bad limiter setting would be if the gain reduction meter showed significant reduction occurring before your input meter hit 0 dB. Or, if the input meter surpasses 0 dB before gain reduction starts.

Once you get everything set, the limiting will work when the signal reaches that threshold, no matter what your receiver’s volume setting is. IOW, if a bass-heavy scene from a movie drives the signal up to that point, even though your main receiver volume is lower than what it was during your set-up procedure, the limiting will kick in.

Hope this helps.

Regards,
Wayne


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## Andysu (May 8, 2008)

http://www.hometheatershack.com/forums/home-audio-subwoofers/13610-subwoofer-protection.html


Drudge said:


> There are jackhammer vibrating sounds on occasion as well it all depends on the movie.Some bass scenes like the Star Wars Episode II beginning flyover scene really bring all the those types of sounds out to were to sub sounds like it's going to melt down.On other movies the bass kicks you in the chest and all is fine on others the bass doesn't seem that intense and it makes the flub,flub,womp,rattle.


Okay so now I know what film to look at and run some tests with it. Star Wars Episode II and the scene I know it far too well now having played that scene…I really lost count well over 20 and 30 times.

Why didn’t you say you had, x3 Behringer DEQ2496, I assumed you only had one?

I’m waiting for the sound system amps to all warm up then I’m going to run test with a slight difference.


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## Andysu (May 8, 2008)

Okay now playing again for the untold time!!!! 

I’ve patched the LFE.1 (onto the single DCX2496 that I use for LCR) using the centre channel input or (channel B) “But that’s not important right now. Is my dog scraps gonna make it though chapter 3 I’m scared mister” LOL

Okay what I have seen so far compared to U-571 that I monitored last night in the same fashion and the mix level on that was within a ±10db difference even on the hard impacting depth charging moments!

What I can see here on Star Wars episode II Attack of the clones” with side-view-flyby region 2 DVD 2m.25s is around an extra +10db on the mix or a really lousy supervision of the transfer from (digital master tape) or some Muppet turning the LFE.1 up +10db far too high?

I’m trying…Doing my best to solve or find a remedy. I had to turn the LFE.1 down on my AVR to -10db. AVR is running at 0db, please don’t try this with yours, you’ll destroy the loudspeakers!


Anyway on the DCX2496 inputs for 
A left front -30db
B LFE.1 -20db
C right front -30db

Now the (above) is with the LFE.1 on the AVR at -10db and that looks like a normal playback level.

Anyway this is just the basic part of the test that I’m running, it gets funky later on!

During the sudden abrupt “fabricated” explosion levels were around 

A left front -30db
B LFE.1 -20db
C right front -30db

Anyway going to set-up spectrumlab now should be interesting.

You know rumour has it that Jar, Jar was going to on the space ship that got blown to smithereens!:rofl2:


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## Andysu (May 8, 2008)

Okay before I start jumping ahead of myself I turned on the audio limiter on 
Channel B and set the LFE.1 back to 0db on the AVR master volume is also 0db.

The flyby same scene as the spaceship passes over the screen at 2m.25s region 2 DVD. The level on the limiter display showed roughly -7db. Ouch too near! 

The explosion was just tickling underneath -6db.

On the inputs 
A left front -30db
B LFE.1 -5db (AVR LFE.1 0db AVR master volume 0db)
C right front -30db

I’ve applied a -10db on the audio limiter that is suppressing some of the aggressive peak level. 

Okay now I’ve applied the THX bass management peak level at -10db and its holding the level…

On the inputs 
A left front -30db
B LFE.1 -20db (AVR LFE.1 0db AVR master volume 0db with THX management peak -10db)
C right front -30db

I need to run some frequency waterfalls to see what damage has been down to the frequency level what frequency has the overall peak level that is taking the level so high!


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## Andysu (May 8, 2008)

Okay note the LFE.1 only frequency waterfall note the bright blinding red spots, kinder looks like Jupiter.

Anyway I’m having my dinner right now! While still taking my time to do this for you! 

The level you see is what is been taken and recorded directly to the pc from the AVR at 0db volume LFE.1 0db.

Anyway I’ll add the audio THX limiter after I have finished my meal…

The top waterfall is the spaceship opening and its landing.

The bottom waterfall is the destruction of the spaceship…or KABOOM!:rofl::hsd:


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## Andysu (May 8, 2008)

Okay now I’ve applied -10db THX bass management limiter and you can see there is a significant drop in level.

I’ve neglected to show the individual levels of LCR. I do have other things that I’d like to do today or what is left of my early evening, so I hope you fully appreciate the time I‘m giving here.









The top waterfall is the spaceship opening and its landing.

The bottom waterfall is the destruction of the spaceship…or kaboom!


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## Andysu (May 8, 2008)

Note: all levels are still at 0db on the AVR main master volume and 0db on the LFE.1 with THX limited turned OFF

Okay now passing the LFE.1 output to direct input on the DCX2496 and the first waterfall that is on the bottom (spaceship kaboom!) marked at 0db the second one above it -10db on the DCX2496 audio limiter and then the third one at the top of the page -17db.


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## Andysu (May 8, 2008)

Okay tested the spaceship haboom again. You really need to get amps that have barograph display read-out and set the levels up a bit more accurately most AVR with internal amps are sheer waste of time with me.









Anyway I’ve applied a 501m/s release time and a 20m/s.


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## Drudge (Sep 1, 2008)

I may have to get a line level converter to get the levels right.I'm planning on getting a Audyssey Pro stand alone unit soon to simplify things and replace 2 of the DEQ's.With the Audyssey in the system I don't think I can push the processor levels up high enough to get the levels I'm getting now to drive the DEQ's to their higher bit levels.I also want to keep a single DEQ for it's great spl meter function as well as for the purpose of using it as a sub-peak limiter.

Thanks Wayne,I'll read more into it.

The Star Wars Episode II dvd just destroys my sub in the opening ship pass by and landing scenes.It's bass is recorded so hot that to watch it I had to reduce the LFE mix level control to -4db so the sub wouldn't bottom out!:doh:


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## Andysu (May 8, 2008)

Drudge said:


> The Star Wars Episode II dvd just destroys my sub in the opening ship pass by and landing scenes.It's bass is recorded so hot that to watch it I had to reduce the LFE mix level control to -4db so the sub wouldn't bottom out!:doh:


Well its due to over playing the level or not having gut instinct to deal with the issue at hand, but that’s why the forum is here to relay the issues and hope that someone can find a viable solution without costing silly amounts of money.

In the meantime I’ll just place a note inside the DVD cover reduce LFE.1 track only -10db. I take it you are using the LFE.1 as a single discrete track and not shoving the THX 80Hz rest of the low end on top of it.

Use second sub to handle the LCRS lows if the LCRS can’t handle it!

Also set levels accordantly for the LCRS should be the same amp and levels EQ timber balance with pink noise cycling from the AVR should sound the same if not with in tiny db fraction.

The LFE.1 set the amp so its within the same level as the rest of the amps or adjust the differences in dip peaks and the (null issue) until the amp behaves in normal functioning level it should be playing with near clip level.

Also depends on you’re floor surface! Mine is concrete type. This helps reduce (buzz rattling vibration sounds cursed by the sub at different frequencies at different SPL db levels). 

The sofa or seat may only vibrate or tickle with certain frequencies at different SPL db levels.

Some of the best THX cinemas one propose made around late 80’s was UCI High Wycombe outside London, rumour is it was “voted best 5th THX cinema in the world”, an old buddy told me, this many years ago, who lived in Buckinghamshire.

The lows ion the cinema was just WICKED and would easily put most home cinema in the dust even if it still had its THX licence, the cinema I believe removed the THX crossover around late to early 2000? Politics I guess. Shame because it was really hard in the stomach and chest even standing at the back of the cinema my clothing was flexing due to the mild lows on Arachnophobia Dolby/SR.

Well at least we have REW to show us the good the bad and the ugly side of the lows and how they should be presented.

Oh, and the THX Broadway trailer almost chocked me to death! It was that deep! I give it 5! :hsd::hsd::hsd::hsd::hsd:


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## Drudge (Sep 1, 2008)

It's mixed with the bass from the mains through the bass management.The LFE mix level is separate control on my processor,but I don't like to use it because it alters the bass mix.I don't have a second sub to use and can't fund another purchase for one right now.If I had second sub I'd probably get the extra headroom to handle everything without a problem though.At least at my listening level.


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## Andysu (May 8, 2008)

Drudge said:


> It's mixed with the bass from the mains through the bass management.The LFE mix level is separate control on my processor,but I don't like to use it because it alters the bass mix.I don't have a second sub to use and can't fund another purchase for one right now.If I had second sub I'd probably get the extra headroom to handle everything without a problem though.At least at my listening level.


I’d say a second one will cut around this issue for you. I guess you want another sub of the same make and model it’s an M&K is it not. I saw you’re signature.

I guess that model would be hard to come by now, maybe a few on eBay going on the cheap, hopeful still intact! 

Having a large best single sub in the world won’t solve the issue as you should know.

Maybe if our rooms where all universal in size and shape the issue might be somewhat different, but its not that ideal is it. The room is the killer sub bass it adds room boom nulls and the nulls is enough to make most climb the walls.:gah:

Anyway try turning off the THX crossover. I don’t even use mine anymore it’s all patched though the DCX2496 that is crossed over at 71Hz at present or any crossover I choice to float my boat high and almighty. LOL

If I use second DCX2496 I’ll send the LCRS into single line input from the audio mixer use the crossover filter and audio limiter for a little bit of extra experimentation.

Use the other input for the LFE.1 and use the outputs in sensible way. Or use one DCX2496 for three subs and send the LCR information to them. Use the audio limiter if necessary. 

In fact all my fronts have audio limiter turned ON just in case. The surrounds I’d just have to wait like you, till I have the funds for another DCX2496.

Mind you I wouldn’t mind several DEQ2496 but the cost in the UK is around £200.00 plus. The DCX2496 is well under £200.00 pounds.

I’m going to re-plug all my leads back up now and run a few scenes from Star Wars episode II. I’ve only got the LRS playing at the moment with the LFE.1 feeding into the pc.

That Watto has lot of flies buzzing around him, wow he must smell real bad!:rofl2:


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## Drudge (Sep 1, 2008)

I have a full 5.1 Mackie setup with the now dicontinued HRS120 sub which has a +10dB switch on the back so I can use that when I use the analog outputs on the players to compensate for the 10dB that they don't add in there bass management schemes.I don't use the DCX which has crossover functions,the DEQ is more a EQ,compresssor,delay processor with no crossover function.

Besides with the Audyssey it will be doing all the EQ.


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## Andysu (May 8, 2008)

Drudge said:


> I have a full 5.1 Mackie setup with the now dicontinued HRS120 sub which has a +10dB switch on the back so I can use that when I use the analog outputs on the players to compensate for the 10dB that they don't add in there bass management schemes.I don't use the DCX which has crossover functions,the DEQ is more a EQ,compresssor,delay processor with no crossover function.
> 
> Besides with the Audyssey it will be doing all the EQ.


Maybe an SRSMyVolume I’m thinking strongly about getting the analogue models for the LCRS/LFE.1, this shouldn’t bust the piggybank like it would with Audyssey on most AVR that seem overpriced! 

If the auto volume can control the frequencies level, then I, see no reason why this shouldn’t work and a little beyond…

SRS analogue levelling adaptor 
http://www.srslabs.comcomersus_suppo...-100 Referer: 

http://www.srslabs.com/store/files/S...S Manual.pdf

http://www.srslabs.com/store/files/M...ptor FAQ.pdf

MyVolume Volume Leveling Adaptor
http://www.srslabs.comcomersus_suppo...-100 Referer: 

http://www.srslabs.com/store/files/M...serManual_.pdf

Youtube videos

How To Install the SRS MyVolume Adaptor


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## Wayne A. Pflughaupt (Apr 13, 2006)

Drudge said:


> I may have to get a line level converter to get the levels right.
> I don't think I can push the processor levels up high enough to get the levels I'm getting now to drive the DEQ's to their higher bit levels.


A common misconception. 24-bit processors work fine with consumer signal levels. It’s only for the equalizer's limiting function that level might be an issue, and that’s only because that’s the nature of limiters, analog or digital.: I.e., they don’t limit low-level signals.

Regards,
Wayne


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