Otto's IB ~~ Coming Together (w/ pics)

**crackyflipside** · **10-25-06, 02:08 PM**

How does the 2500 amp handle for you?

BTW, we would love to see some REW graphs, Otto!

**Otto** · **10-25-06, 03:19 PM**

Hey guys,

First, thanks for the comments on the kid -- she is our sweetheart!

As to the amp -- no problems there. I've never had it clip or seem to have any troubles whatsoever. When I first got the IB together, I was cranking pure tones through it (from maybe 10 Hz to 60 Hz). No clipping, no clanking. The drivers were moving strongly. I did not turn things up to max by any stretch (niether at the preamp nor at the amp), and I still had more to go in the amp and the drivers as far as I could tell. The bass I was getting at that time was way more than enough.

Same goes for the M5 18s. No troubles. They're a great price, even with shipping.

I can post some REW graphs, but I haven't been totally happy with the results yet. It stinks to not be ablet to use the BFD at < 20 Hz, as I can see some humps down there. I'm also dubious about the accuracy of the RS SPL meter at < 20 Hz. I did some REW/BFD setup and I've been living with it they way it came out, which isn't bad.

My wife will be out with the girls the next two nights, so I'll plan on making some graphs and post them later this week.

Chris, IIRC, you are on AVS talking about doing a 4x18 M5 IB. I don't think you will be disappointed in the performance of the drivers or the abundance of the bass. And once you BFD it, it's great! The IB sound is different, and I will have to agree with any comments that have described is as "just there" and "less boxy" or "less boomy". It's just smooth and everywhere. I'm still tweaking on it, but so far, I love it. Plus, the WAF and stealth factor is sweet!

**mrogowski** · **10-25-06, 04:15 PM**

If any of you guys outgrow your Behringer amp, might I suggest a unit I just ordered:

http://www.crest-performance.com/pre...ion/view/id/20

The 3.0 is simply a monster. I had to have it!

The 2.0 would probably fit the bill nicely. I was quoted ~$850CA for it - that was before the haggling. You folks south of 49 would probably get it cheaper.

Just an idea...

Best,
Mark

**Exocer** · **10-25-06, 06:57 PM**

Yeah, I'd have to agree Otto. Roughly $100 shipped per 18" driver is a great deal.

mrogowski, nice amps indeed. I like the idea of the variable low-cut filter (CPX 3.0 model only?) too bad its lowest setting is 20hz

**mrogowski** · **10-25-06, 08:28 PM**

I agree. The high pass filter would be useless for what you guys are doing, but the low pass sub crossover is a nice add-on for those who don't have one yet.

For sheer mustle, power and driver control, the Crest is *very* hard to beat - for the price.

Best,
Mark

**Otto** · **10-26-06, 10:41 PM**

OK. Its "girls' night out" tonight, which means I was able to do a little more tweaking with the REW/BFD combo.

Here is the initial, unfiltered response of the IB alone:

unfiltered.jpg

Here's a first pass (well, OK, maybe second or third pass...) at a flat response. I think it's looks pretty good. I could probably pay more attention from 60 to 80 Hz. I certainly wish that the BFD could process < 20 Hz...

filteredflatnohousecurve.jpg

Here's a pass at a house curve that is up 8 dB at 32 Hz and 0 dB at 60 Hz. Not bad. Same complaint re: < 20 Hz.

filteredwithhousecurve.jpg

Fortunately, my daughter seems to sleep through everything, and my wife is out, so I was able to turn it up a little.

As far as maximums, I was easily able to hit 120 dB at ~ 2 ft from the opening of the IB. It was pretty loud. I honestly would not be surprised if a window broke, or if the drwall cracked, etc. Seriously. I would have to agree with Ayreonaut in that it's "scary". As far as I could tell, I still had more amp to go, and the drivers were nowhere near xmax. I guess I could have turned it up louder still?!?! There is no way you would ever need that amount of bass during any movie or musical experience. In order for the rest of the frequency spectrum to be in line with that level of bass, the overall SPLs would be painful.

"Darla tapping" in Finding Nemo, the "asteroid chase" in Attack Of The Clones and, of course, the "lightning" and "first pods" scenes in War Of The Worlds were all very present and tactile without being too in-your-face (unless you want them to be). I can definitely "feel it." It's much more capable than my previous subs, even when using an M&K 2x12 and one 12" in each of my DefTechs. Of course, there's just a lot more sub with the IB. More dislacement, more power and, apparently, way more headroom. I've definitely bottomed-out my M&K on stuff like WOTW, and it was nowhere near this level of output (of course).

As far as mucic goes, I've just, as I've been typing this, been listening to Steely Dan's "Peg", Sting's "Lazarus Heart" and "Island of Souls", a few Diana Krall tracks, Dido's "Thank You", a couple Tool tracks, and Gorillaz "Dare" (should that be something like "Gorillaz's"?). Everything is sounding great. It's necessary to adjust bass level from CD to CD, but once you get it to your liking, it's nice.

So... overall, I'm very pleased with this "mostly final" product (there are still some cleanup type things to do, still no grille, etc.). I've never really had any nice subs (e.g., SVS, Velodyne, etc.). My previous was an M&K. It was OK for a small room, but just couldn't cut it in this one. I think that I would have to pay many thousands of dollars to get to these quantities and qualities of bass. Don't get me wrong, I'm certainly not knocking any sub manufacturer. From what I've seen, the new, intentional sub companies are making great subs. As we all know, DIY's bang for the buck is part of the attraction of DIY.

Anyway, rather than sitting here any longer tonight, I'm actually gonna use this thing.

Have a good night!

**kramskoi** · **10-27-06, 12:34 AM**

Quote:

Otto wrote:

OK. Its "girls' night out" tonight, which means I was able to do a little more tweaking with the REW/BFD combo.

Here is the initial, unfiltered response of the IB alone:

Attachment 1010

Here's a first pass (well, OK, maybe second or third pass...) at a flat response. I think it's looks pretty good. I could probably pay more attention from 60 to 80 Hz. I certainly wish that the BFD could process < 20 Hz...

Attachment 1011

Here's a pass at a house curve that is up 8 dB at 32 Hz and 0 dB at 60 Hz. Not bad. Same complaint re: < 20 Hz.

Attachment 1012

Fortunately, my daughter seems to sleep through everything, and my wife is out, so I was able to turn it up a little.

As far as maximums, I was easily able to hit 120 dB at ~ 2 ft from the opening of the IB. It was pretty loud. I honestly would not be surprised if a window broke, or if the drwall cracked, etc. Seriously. I would have to agree with Ayreonaut in that it's "scary". As far as I could tell, I still had more amp to go, and the drivers were nowhere near xmax. I guess I could have turned it up louder still?!?! There is no way you would ever need that amount of bass during any movie or musical experience. In order for the rest of the frequency spectrum to be in line with that level of bass, the overall SPLs would be painful.

"Darla tapping" in Finding Nemo, the "asteroid chase" in Attack Of The Clones and, of course, the "lightning" and "first pods" scenes in War Of The Worlds were all very present and tactile without being too in-your-face (unless you want them to be). I can definitely "feel it." It's much more capable than my previous subs, even when using an M&K 2x12 and one 12" in each of my DefTechs. Of course, there's just a lot more sub with the IB. More dislacement, more power and, apparently, way more headroom. I've definitely bottomed-out my M&K on stuff like WOTW, and it was nowhere near this level of output (of course).

As far as mucic goes, I've just, as I've been typing this, been listening to Steely Dan's "Peg", Sting's "Lazarus Heart" and "Island of Souls", a few Diana Krall tracks, Dido's "Thank You", a couple Tool tracks, and Gorillaz "Dare" (should that be something like "Gorillaz's"?). Everything is sounding great. It's necessary to adjust bass level from CD to CD, but once you get it to your liking, it's nice.

So... overall, I'm very pleased with this "mostly final" product (there are still some cleanup type things to do, still no grille, etc.). I've never really had any nice subs (e.g., SVS, Velodyne, etc.). My previous was an M&K. It was OK for a small room, but just couldn't cut it in this one. I think that I would have to pay many thousands of dollars to get to these quantities and qualities of bass. Don't get me wrong, I'm certainly not knocking any sub manufacturer. From what I've seen, the new, intentional sub companies are making great subs. As we all know, DIY's bang for the buck is part of the attraction of DIY.

Anyway, rather than sitting here any longer tonight, I'm actually gonna use this thing.

Have a good night!

what behringer model are you using? The dsp1124 won't allow you to boost the bottom end because the filter widths are'nt wide enough (2 octaves iirc). Any of the 2496 models will allow up to 10 octave filter widths...this is what you will need to affect the lower frequencies...it looks like from the rat shack sweep, you are down a significant amount (~16 dB) at 12 Hz...this a steep roll off from 15 Hz and i'm not sure how much a 2496 could flatten it, with 20 Hz being the lowest center...you could set the filters wide but you can only shelve up the response you already have...it's definitely doable though and you would notice the difference of course...you'll still have that steep roll off though...

**Chrisbee** · **10-27-06, 01:14 AM**

Quote:

kramskoi wrote:

what behringer model are you using? The dsp1124 won't allow you to boost the bottom end because the filter widths are'nt wide enough (2 octaves iirc). Any of the 2496 models will allow up to 10 octave filter widths...this is what you will need to affect the lower frequencies...it looks like from the rat shack sweep, you are down a significant amount (~16 dB) at 12 Hz...this a steep roll off from 15 Hz and i'm not sure how much a 2496 could flatten it, with 20 Hz being the lowest center...you could set the filters wide but you can only shelve up the response you already have...it's definitely doable though and you would notice the difference of course...you'll still have that steep roll off though...

I'm afraid you are mistaken about the 1124P.

I have a wide +16 dB BFD boost filter @ 20Hz on my IB.

My REW curves show that this works well at least as low as 10Hz and probably beyond that point. (if I could measure it!)

Click my signature for the comparison graphs.

**Otto** · **10-27-06, 07:39 AM**

Quote:

kramskoi wrote:

what behringer model are you using?

Hi there,

I'm using the 1124. I played around with that a little, putting a wide filter at 20 Hz. It seemed to have some impact at < 20 Hz, but I didn't follow through with it too much. I may revisit that. Yeah, the steep roll off may or may not be treatable in the end. I'm also a bit dubious about the RS SPL meter to measure that low. I am using the latest correction numbers, but I would prefer to have a mic.

Thanks!

**Otto** · **10-27-06, 07:42 AM**

Quote:

Chrisbee wrote:

I'm afraid you are mistaken about the 1124P.

I have a wide +16 dB BFD boost filter @ 20Hz on my IB.

My REW curves show that this works well at least as low as 10Hz and probably beyond that point. (if I could measure it!)

Click my signature for the comparison graphs.

Hi Chris,

I had a look at your graphs. Looks good! I think I'm gonna go back and try one at 20 Hz on mine.

**Chrisbee** · **10-27-06, 08:25 AM**

Quote:

Otto wrote:

Hi Chris,

I had a look at your graphs. Looks good! I think I'm gonna go back and try one at 20 Hz on mine.

If you do boost at 20Hz you will need to bring the new response hump above 20Hz down to the target curve with some spaced negative filters. Or you really won't gain anything. The upper bass will just swamp the lower frequencies which you are trying to expose more clearly. Watch your driver excursion very carefully. It doubles and doubles again with falling frequency even at the same output level.

I would creep up very slowly on a suitable filter boost rather than crank in a load of extra dBs @ 20Hz and hope for the best. Suddenly hitting the end stops could be costly! You need to be certain that the next blockbuster won't suddenly find your driver's limits! Lots of headroom allows you to relax and enjoy the film instead of sitting there worrying. The 25-60Hz area is where the audible bass energy in films is situated. Anything lower is just an enjoyable bonus in physical sensation and the most difficult to obtain in large quantities.

**mrogowski** · **10-27-06, 12:05 PM**

If memory serves, the DCX2496 has a subsonic filter being applied starting at 20Hz and is not configurable. IOW, you cannot turn it off. I'd double check the other Behringer units to see if the same thing is being applied to them as well.

Best,
Mark

**kramskoi** · **10-27-06, 02:52 PM**

Quote:

Chrisbee wrote:

If you do boost at 20Hz you will need to bring the new response hump above 20Hz down to the target curve with some spaced negative filters. Or you really won't gain anything. The upper bass will just swamp the lower frequencies which you are trying to expose more clearly. Watch your driver excursion very carefully. It doubles and doubles again with falling frequency even at the same output level.

I would creep up very slowly on a suitable filter boost rather than crank in a load of extra dBs @ 20Hz and hope for the best. Suddenly hitting the end stops could be costly! You need to be certain that the next blockbuster won't suddenly find your driver's limits! Lots of headroom allows you to relax and enjoy the film instead of sitting there worrying. The 25-60Hz area is where the audible bass energy in films is situated. Anything lower is just an enjoyable bonus in physical sensation and the most difficult to obtain in large quantities.

okay Chris...you are correct as far as IB is concerned...we are coming from two different applications...16 dB of boost at 20 Hz would not be possible with most sealed subwoofers and i would be concerned for your setup with this much boosting down low (without an airspring)...That said, your IB system seems very capable as you've noted...i was only stating that you have more flexibility with one of the 2496 units because the max filter width on the dsp1124 is 2 octaves (120 on the jogwheel)...i just could'nt use it with my 2x15...i needed wider filter widths (up to 10 octaves)...with these widths you only need two shelving filters to shape the response/ Q curve "and" keep group delay as low as possible...

**Otto** · **10-28-06, 10:27 AM**

I had a chance to play with boosting at 20 Hz to clean up the dip at 15 and below. Filters at 20 Hz definitely affect < 20 Hz. I also cranked up my levels so that they were above my target, and I could easily reduce them with the BFD. I can definitely tell the difference in WOTW and such. No clipping on the BFD output, no clipping on the amp, no bottoming on the drivers. Apparently lots of headroom!

filteredwithboostat20hz..jpg

**crackyflipside** · **10-28-06, 12:06 PM**

Those graphs look awesome and give me something to look forward too!

**SteveCallas** · **10-28-06, 12:18 PM**

Looks pretty good - I think subsonic issues are a result of the driver's being used - they don't seem to be the most efficient down low with the high Fs, high Bl, and relatively low xmax. For the cost though, you can't really complain.

**jagman** · **10-28-06, 01:50 PM**

Man... those plots do look good. If I add more than 3dB boost at 20 Hz (BW/60=120) the upper bass get way too hot and it happens reqardless of how much I cut the 50-90Hz range. It's very frustrating. I've cut to the point on REW that it's 15-20dB below the curve and the in room response is still 15-20 dBs hotter than I want it. It's really strange. The in room response is the same whether I cut the upper bass or not... always 15-20 dBs hot.

**brucek** · **10-28-06, 03:49 PM**

Quote:

If I add more than 3dB boost at 20 Hz (BW/60=120) the upper bass get way too hot and it happens reqardless of how much I cut the 50-90Hz range.

I have to think that you are entering something incorrectly. The effect of the filter you propose doesn't really have much of an effect. It could easily be overcome by other filters.

Sometimes in the areas above the crossover, it's the mains influence that counteracts any attempt to lower the level at that frequency with the sub/BFD.

Below is a graph of a standard target of 80Hz overlayed with the same target combined with a 20Hz +3dB filter with a bandwidth of 120/60...

What is it you're actually attempting to do?

filters20.jpg

brucek

**jagman** · **10-28-06, 04:34 PM**

All I'm trying to do is supplement the lower frequencies (with caution). When doing it more than 3dB (which isn't much), the 50-80Hz range gets a major boost that cannot be overcome by additional negative filters. In theory, I should be able to alter the filters so the new plot is the same as my music plot from 40Hz and up, but for an unknown reason, putting those cuts in doesn't make a difference. Not only that, but if I cut 10-15dB below the target curve, the actual in room measurements stay at the boosted level. It doesn't make any sense, but that's what I'm measuring. The test tones haven't changed. The REW plot shape without filters hasn't changed. The microphone location hasn't changed. The only thing that has changed is the boost at 20 Hz. I've literally spent about 6 hours trying get the right filter combination to get this to work, but nothing is panning out. In fact, the wife's even ****** at me because I'm not doing the dishes, folding the laundry, etc. She says I'm obsessed. She just doesn't understand

. WRT the interaction between the mains and the sub, they integrate beautifully with my music curve, just not after boosting the lower frequencies despite the plot above 50z looking identical on REW.

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