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post #181 of 219 Old 12-30-2013, 09:42 AM
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Replacing the horn mid and SEOS-12 with a SEOS-24 and BMS coax would also do nicely.

Mike
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post #182 of 219 Old 12-30-2013, 09:48 AM
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Quote:
Originally Posted by tuxedocivic View Post

I agree with Coctostan on your FR. And using the filter slope to manage some of the response. I prefer using the knee of the slope to control response rather than stuffing it with a high order filter and using PEQ to crank everything into place. Don't have a reason why. Just do.

Yep, that was just Scott's preliminary setup. Crossover design is far more nuanced than just filtering to get flat response. I could set a DSP 10 signficantly different ways to achieve the same on-axis response and they will all sound rather different. The biggest difference is in the off-axis behavior usually and that can vary significantly based upon the slopes used. Steeper slopes are more likely to make a mess of off-axis response. If the drivers can handle the bandwidth, I generally get better results with shallower slopes. Of course each design presents different challenges and you have to use the right approach and tool for the job.

Here is a model of the on-axis response of the midhorn with delta 10:



You can see the rising response and how the dips align with Scott's response.

This is why I'm a broken record when people mention using a DSP as an easy way to design a loudspeaker. It is an easy way to get up and running relative to passive components and there are countless benefits, but it doesn't eliminate the fact that techniques used to optimize the DSP crossover are still needed. I've "fixed" a few designs where the person simply "turned knobs" (or nowadays clicked the mouse) to get a flat on-axis response. The speaker measured the same on-axis but sounded far better.
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post #183 of 219 Old 12-30-2013, 10:01 AM
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Stan and Tux,

I believe what you say is true about off-axis response and steep slopes in the crossover region, but I don't understand why. Is there a discussion or reference you can point me to that covers this in greater detail.

Thanks in advance,
Mike
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post #184 of 219 Old 12-30-2013, 10:28 AM - Thread Starter
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Lol. Guys. Let's not get ahead of ourselves. I never said this is a finished ... whatever. I haven't even left the dealer's lot yet with these. biggrin.gif

THE WORK HAS YET TO BEGIN!!!

I need to be able to make proper measurements I can trust, first. wink.gif

And just a quick response to Coctostan's thoughts on people and DSP.... hey, that's not me. I'm taking all the proper steps. I'm not just some yahoo with big speakahs! tongue.gif And actually I think my posted response so far only confirms that I have taken all the correct steps to get a proper response. All that on the first try. Gee, I guess I'm just lucky. rolleyes.gif

This is an advanced class with and advanced professor...lol, me. All the Speaker 101 stuff can take a bench seat in my classroom. tongue.gifbiggrin.gif

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post #185 of 219 Old 12-30-2013, 10:51 AM
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I probably should have worded my post better. I know you weren't doing the DSP as a quick fix. Is there anything quick about this project? smile.gif Many people are attracted to DSP though because they assume it does the heavy lifting for them and that is not true...assuming you have lofty goals. I assume the goals are lofty when someone wants to combine uber-woofer with uber-horn that nobody else has designed for. It is a little bit like the guys who build $10k motors with $3k turbos and refuse to spend $1k to have it properly tuned.

When you get those measurements I think it would be interesting to see what different DCX settings people come up with. There is no single right answer, but there are lots of wrong answers.
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post #186 of 219 Old 12-30-2013, 10:57 AM - Thread Starter
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Quote:
Originally Posted by coctostan View Post

I probably should have worded my post better. I know you weren't doing the DSP as a quick fix. Is there anything quick about this project? smile.gif Many people are attracted to DSP though because they assume it does the heavy lifting for them and that is not true...assuming you have lofty goals. I assume the goals are lofty when someone wants to combine uber-woofer with uber-horn that nobody else has designed for. It is a little bit like the guys who build $10k motors with $3k turbos and refuse to spend $1k to have it properly tuned.

When you get those measurements I think it would be interesting to see what different DCX settings people come up with. There is no single right answer, but there are lots of wrong answers.

Well said, my friend and sorry if my post came off as sarcastic or aggressive towards you. It most certainly was not or meant to be. I sent you a nice PM. wink.gif

I don't see too much of this around here but I know what you mean. I never intended to use the digital gear as a crutch but more because I felt it was a very powerful tool that granted me nearly endless flexibility and configuration possibilities. Mind boggling!!! biggrin.gif


No, I don't want to give the wrong impression. I DO very much intend to concentrate on getting everything just right and set up as well as possible. Thankfully though I've got the rest of my life to do it. I'm just enjoying what I have now. It took a long time to get to this point and I just want to have some fun. smile.gif

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post #187 of 219 Old 12-30-2013, 11:04 AM
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Quote:
Originally Posted by mhutchins View Post

Stan and Tux,

I believe what you say is true about off-axis response and steep slopes in the crossover region, but I don't understand why. Is there a discussion or reference you can point me to that covers this in greater detail.

Thanks in advance,
Mike

When the slopes are shallow, there's more blend between the drivers over a wider band width. So if the drivers behave differently, it'll be blended. Simple as that really.
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post #188 of 219 Old 12-30-2013, 11:13 AM - Thread Starter
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Just some fun facts of this project since you guys are interested.

I did try using all 24dB/oct L-R filters on the get-go (using pretty much the same xover frequencies I am now) and got much worse looking FR measurements than I did with what I have now which is mostly 12dB/oct Butterworth filters. The next key was using some small delay on certain components and that snapped things into focus real well. I still very much need to tweak.... ALL of that. tongue.gif

I'm having fun though! smile.gif Changing settings is a breeze. Keeping up with all the settings across three channels and three devices though. Oye! tongue.gif

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post #189 of 219 Old 12-30-2013, 11:15 AM
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Quote:
Originally Posted by tuxedocivic View Post

When the slopes are shallow, there's more blend between the drivers over a wider band width. So if the drivers behave differently, it'll be blended. Simple as that really.

But why should that differ between on-axis and off-axis?

Part of the choice for a crossover point is to find not only a good blend between drivers but to avoid where the drivers start to misbehave at the extremes of their frequency response. If you have several octaves of good behavior / smooth frequency response, certainly a shallow crossover can work. But what if you don't have that luxury? Does the off-axis response tend to become more ragged sooner than the on-axis response for most drivers?

Is part of the issue related to the phase response of higher-order crossovers?
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post #190 of 219 Old 12-30-2013, 11:52 AM - Thread Starter
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Quote:
Originally Posted by dominguez1 View Post

Sick Scott, just sick response! congrats!

Noticed you didn't chart to 5hz, does your signal chain start to rolloff at 10?

I do believe it continues below 10hz. You know it just defaults to showing a range to 10hz and you have to click to arrow at the bottom and when I took the screenshot I guess I hadn't done that yet. I usually do that first thing.

In the future I will try and keep these things consistent but right now I'm just throwing out the best stuff I can get. Plus I want to keep the discussion fresh. smile.gif

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post #191 of 219 Old 12-30-2013, 11:57 AM
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Fresh? This should do it


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post #192 of 219 Old 12-30-2013, 12:38 PM - Thread Starter
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Lol! tongue.gif

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post #193 of 219 Old 12-30-2013, 02:29 PM
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Quote:
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... Thankfully though I've got the rest of my life to do it. I'm just enjoying what I have now. It took a long time to get to this point and I just want to have some fun. smile.gif

Very cool, have fun ... this is the fun stuff.

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post #194 of 219 Old 12-30-2013, 02:34 PM
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Mhutchins, even though you have the right idea, its never that simple. This is something I used to argue with Penngray about. He used steep slopes. There's pros and cons to both.

Woofers in particular tend to beam more and more rapidly, unlike a well designed waveguide that is fairly controlled. So having shallow slopes can help there. Also, if there's a response anomaly, sometimes they can be opposite and complimentary.
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post #195 of 219 Old 12-30-2013, 07:43 PM
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Very nice, find a dancing partner and go to town.
ps. thanks for the advice on the three tempests , they sound great.
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post #196 of 219 Old 12-30-2013, 11:51 PM
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Thanks, Tux!

Scott, this is an awesome project you've got here. Thanks for letting me continue my education while drooling at the pictures you've posted.

Mike
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post #197 of 219 Old 12-31-2013, 07:27 AM
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"Here is a model of the on-axis response of the midhorn with delta 10."

until scott posts a sweep of his, here is a measurement by wayne




http://audioroundtable.com/forum/index.php?t=msg&th=16581#msg_num_4

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post #198 of 219 Old 12-31-2013, 08:26 AM
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Fresh? This should do it


Beast my lawyer will be in contact, my retinas were burnt by that photo!

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post #199 of 219 Old 12-31-2013, 09:19 AM
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Quote:
Originally Posted by mhutchins View Post

But why should that differ between on-axis and off-axis?

Part of the choice for a crossover point is to find not only a good blend between drivers but to avoid where the drivers start to misbehave at the extremes of their frequency response. If you have several octaves of good behavior / smooth frequency response, certainly a shallow crossover can work. But what if you don't have that luxury? Does the off-axis response tend to become more ragged sooner than the on-axis response for most drivers?

Is part of the issue related to the phase response of higher-order crossovers?

Crossover design, like most technical design is an exercise in compromises. Even choosing the drivers is a part of the overall design. In the simplest sense, a loudspeaker filter is used to limit each driver to its appropriate on-axis usable range. More refined designs, account for the off-axis response and steeper filter slopes can negatively (and sometimes positively) affect the off-axis response. Experience and an understanding the fundamental concepts of speaker design helps to come up with a refined design. This will become more apparent when Scott is able to post some complete measurements and we can post some design examples.

Focusing all design energy, especially at the crossover design phase, on attenuating breakup is misguided. First, choose drivers that can be operated more easily within their limits. Driver selection is part of the design process. Second, you are generally presented with the following design choice:

1. Breakup that is down by 30db on-axis and a smooth off-axis response at crossover with a shallow slope

or

2. Breakup that is down by 60db on-axis and an abrupt off-axis response at crossover with a steeper slope

My research and experience always push me towards the first choice. I view that as the fundamental crossover design quandry at the crossover stage. Of course, the best way to make that design quandry manageable is to choose drivers, horns, physical layout, baffle shape, etc that allow for positive compromises. Scott could have chosen to go straight from the 4 2226's to the SEOS12 and that would have necessitated steep filters to deal with null issues, but the speaker would be a mess. Steep filters tend to be a blunt tool used to cover up poor choices in the physical design phase. Shallow slopes are a luxury that is sometimes afforded by good choices in driver selection. Obviously there is a balance to be had like with any design.

Also of note, there is sometimes confusion between the electrical and acoustic response slopes. The electrical transfer function slope might only need to be first order to achieve a 4th order acoustic slope in some cases. The acoustic slope is ultimately the target and that is missed by many people, especially when using DSP active crossovers because it is easy to just set "LR4@1khz" but in this case that would result in something like a 6th or 7th order slope when combined with the natural roll off of the midhorn. If there was severe breakup at 1.1khz and you wanted response up to 1khz you might need a slope that steep, but I can guarantee you the off-axis response will be a mess and that will adversely affect the subjective result. Brickwall electrical filters are fool's gold in HiFi (there might be other arenas where it is useful of course).
Quote:
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"Here is a model of the on-axis response of the midhorn with delta 10."

until scott posts a sweep of his, here is a measurement by wayne




http://audioroundtable.com/forum/index.php?t=msg&th=16581#msg_num_4

That seems to peak less than the on-axis simulation from HornResp. HR is not as complete when simulating higher frequencies (not a flaw, just not in its scope).

Looking at that response, what I would do with a DSP is notch out the breakup from 1.8khz to about 4khz with a PEQ. Then apply a LPF filter of an appropriate Q and slope to approximate a textbook slope centered around 1.4khz (maybe just a 6db LPF to get a nice LR2 acoustic response...sims would provide that answer). That should allow for a corresponding textbook acoustic alope from the SEOS12 in that same area. That goal would be to balance the need for excursion control on the DNA360, cleaning up the Delta 10 breakup and very smoothly transitioning directivity from the midhorn to the SEOS horn. Disclaimer: I'm eyeballing this so don't take the specific numbers to mean anything.
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post #200 of 219 Old 12-31-2013, 10:51 AM
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Thanks, Stan.

Lots more to learn...smile.gif
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post #201 of 219 Old 12-31-2013, 01:35 PM
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Thanks, Stan.

Lots more to learn...smile.gif

No problem. We all have lots to learn and that is a big part of the fun.
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post #202 of 219 Old 06-15-2014, 01:30 PM
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Any updates on this epic system?


Any additional measuring or subjective elements to share?

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post #203 of 219 Old 06-16-2014, 12:30 PM
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post #204 of 219 Old 06-17-2014, 04:38 AM
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Coctostan, you mentioned about had Scott gone with the quad 2226's straight to the Seos-12's with no mid-horn, that he would have to use steep filters in order to avoid the null.

Can you explain to me how & why this null would have occurred?

I am going to try my hand at setting up a active crossover using my Behringer iNuke1000dsp's that will be powering, EQ'ing, and crossing over my Seos-15 * DNA-360 + duel JBL-2226.

I have only limited crossover design knowledge and almost no experience. If anyone would like to help me setup these three active speakers by perhaps emailing &/or text messaging measurements back & forth I would be so greatful!

Feel free to PM if you can offer any assistance!
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post #205 of 219 Old 06-17-2014, 12:56 PM
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Woah
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post #206 of 219 Old 06-20-2014, 03:12 AM
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Marty, are you looking to run the 2226s vertically like a TMM or horizontally? Either way, my measurements of dual 15's should help: Outdoor GP measurement of dual TD15M

The thing to remember is these SEOS wgs are meant to have a smooth directivity hand-off to the next driver. This works with the SEOS12 by crossing to a direct radiator of similar dimension at around 1.1-1.2khz (the wl at 1125hz is about 12" long) because the beamwidth of each device are about the same at this region. With a horizontal 15" layout like I show in my thread you've basically got a 36" radiator which is beaming like crazy at 1khz. A vertical 15" setup would work, at least in the horizontal plane, because the width is similar to the SEOS.

The other thing to remember is that when you have 2 sound sources separated by a distance when they are within 1/4wl of the highest freq of interest they will sum coherently. At 1/2wl and beyond you get destructive summation and get notches in the response. So at 1khz we have a wl of about 13". 13/4=3.25". Obviously with a 15" direct radiator we can't get that close to the wg but you can fudge here depending on the vertical listening window you want.

With my horizontal 15" setup, you can see how ugly the response is at 1khz off axis. You could optimize this for 1 position in space, but that's not practical nor would it be good practice. If you are doing a vertical 15" stack my results should give you an idea of the vertical polar response of the woofers. You can see this isn't very smooth, with a narrowing of directivity around 400hz (beaming) and then some strange behavior around 800hz where the pattern is really wide. This may or may not work to tame floor and ceiling reflections.

IMO, you best bet is to use the 2226s vertically, only add two more channels of amplification and dsp to roll the bottom woofer off around 2-300hz. When designed correctly, this will give you smooth directivity from the top 15" to the wg as it's intended, and a little more midbass dynamics and possibly a better in room response in this region than with one 15" by itself. You could also look into Parham's approach of flanking woofers, by having the lower woofer near the floor and a bit to the side and behind your main speaker to smooth the midbass response. This is kinda what I'm going for. I wouldn't (and don't) use either vertical or horizontal setup all the way up to 1khz+. More like 3-400hz max.
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post #207 of 219 Old 06-20-2014, 04:45 PM
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Quote:
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Marty, are you looking to run the 2226s vertically like a TMM or horizontally? Either way, my measurements of dual 15's should help: Outdoor GP measurement of dual TD15M

The thing to remember is these SEOS wgs are meant to have a smooth directivity hand-off to the next driver. This works with the SEOS12 by crossing to a direct radiator of similar dimension at around 1.1-1.2khz (the wl at 1125hz is about 12" long) because the beamwidth of each device are about the same at this region. With a horizontal 15" layout like I show in my thread you've basically got a 36" radiator which is beaming like crazy at 1khz. A vertical 15" setup would work, at least in the horizontal plane, because the width is similar to the SEOS.

The other thing to remember is that when you have 2 sound sources separated by a distance when they are within 1/4wl of the highest freq of interest they will sum coherently. At 1/2wl and beyond you get destructive summation and get notches in the response. So at 1khz we have a wl of about 13". 13/4=3.25". Obviously with a 15" direct radiator we can't get that close to the wg but you can fudge here depending on the vertical listening window you want.

With my horizontal 15" setup, you can see how ugly the response is at 1khz off axis. You could optimize this for 1 position in space, but that's not practical nor would it be good practice. If you are doing a vertical 15" stack my results should give you an idea of the vertical polar response of the woofers. You can see this isn't very smooth, with a narrowing of directivity around 400hz (beaming) and then some strange behavior around 800hz where the pattern is really wide. This may or may not work to tame floor and ceiling reflections.

IMO, you best bet is to use the 2226s vertically, only add two more channels of amplification and dsp to roll the bottom woofer off around 2-300hz. When designed correctly, this will give you smooth directivity from the top 15" to the wg as it's intended, and a little more midbass dynamics and possibly a better in room response in this region than with one 15" by itself. You could also look into Parham's approach of flanking woofers, by having the lower woofer near the floor and a bit to the side and behind your main speaker to smooth the midbass response. This is kinda what I'm going for. I wouldn't (and don't) use either vertical or horizontal setup all the way up to 1khz+. More like 3-400hz max.
So what do you suggest I do in order to get to optimal response from the 2226's to the Seos-15+DNA-360 combo? Would this be a good candidate for a mid-range driver? I assumed that the Seos-15 and DNA-360 combo could be crossed as low as 900hz or possible even 850hz to the 2226. (Oh and please note that I have scaled back to one single 2226 per tower).
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post #208 of 219 Old 06-20-2014, 11:24 PM
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marty, all the designs offer different sets of tradeoffs, which is why you (and many others) have had such a difficult time trying to identify "the best". the two way 2226/seos15/dna360 is a good combo if you get a good crossover network on it. 3-way complicates things quite a bit, so you may end up worse off even if somewhere in the combination there is some greater potential.

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post #209 of 219 Old 06-20-2014, 11:28 PM
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the two-way horn/15" concept is going on 80 years now.


just as good now:


http://www.jblpro.com/www/products/r...erence-monitor


as it was then:


http://www.audioheritage.org/html/pr...mco/iconic.htm

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post #210 of 219 Old 06-20-2014, 11:59 PM
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Quote:
Originally Posted by Martycool007 View Post
So what do you suggest I do in order to get to optimal response from the 2226's to the Seos-15+DNA-360 combo? Would this be a good candidate for a mid-range driver? I assumed that the Seos-15 and DNA-360 combo could be crossed as low as 900hz or possible even 850hz to the 2226. (Oh and please note that I have scaled back to one single 2226 per tower).
The SEOS 15 may barely get you there for directivity but I've read many times that various CDs sound strained at 800hz with the user opting to move it up into the mid-900's. Above that the 2226 is beaming.

Post 13:
1 inch CD Comparison (SEOS18)

Post 32 comments on the 4550 at 800hz which you have mentioned before as a usable point for the BMS:
http://www.diyaudio.com/forums/multi...c-de250-4.html

Size limitations that I'm limited to aside, I still wouldn't go this 15" route. I would go 12" with the SEOS 15 and settle into 1000hz or the SEOS12 at 1150hz for a less strained presentation from the CD.

Are you doing this for SPL? If not, you can get a much cleaner sound by not pushing the CD so low and getting a mid driver that cleanly plays higher in freq
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