Need help designing serious bass solution for a big theater..horns vs ported or both? - AVS Forum
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post #1 of 411 Old 07-26-2014, 05:44 PM - Thread Starter
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Need help designing serious bass solution for a big theater..horns vs ported or both?

Hi everyone my name is Mike and I'm a bassaholic.... wait is that not how we start here ? lol...
Ok needless to say I've been bitten by the DIY bug, and I'll be leaning on this forum and DIY for my entire speaker package and bass solution for my dedicated theater build that's is starting up in the fall. I've learned a tremendous amount from the awesome people of this forum and for that I'm sincerely grateful! So huge thanks for that! I'm hoping for a little help once again and looking for great ideas and suggestions for a bass solution.

My theater is going to be 36' long by 25' wide with soffits on the sides starting at 8' ceiling height, and the center ceiling extending up to about 10 feet tall. Technically the ceiling is going to be stepped, and coffered but that's for another thread. This theater will be on top of a garage (new construction). The walls and the room will be properly treated, with thick treatments on the walls behind fabric frames, and bass traps in the corner. It will feature double or triple layers of DW+GG, and will be designed for a low noise floor. I don't care about bass escaping the theater though. It's going to be a big space and I'd like big output! But here comes the problem... $$$$ !!! My wife and I just had twins, and we are doing a home remodel as part of this project. My wife is out of work and we are tight on funds. I've already committed to doing my room right and not compromising so I can chase this hobby for decades in my space, even if that means I'll be sitting in folding lawn chairs to start because I can't afford theater seats yet.

Most of the time you hear people complain about size, or space... or WAF. NOT HERE! This isn't going to be some pussified WAF factor build. My screen wall will be at least 3 feet deep and I'm totally ok with designing the room around my bass solution, even if that means I need to vaneer and stain finish a 80 cubic foot sub box in the back as part of the room. NO RESTRICTIONS ON SIZE, WOOD COSTS, OR COMPLEXITY OF BUILD ! Now that I'm clear about that... we can continue.

I don't think IB or sealed subs are the right solution for me. I've been looking at ported subs vs horns or possibly integrating sealed + ported + horns, but I also understand the reasons you might not want to do that (phase issues and all that).

Ideally I'd like 10db over reference output, and I'd like some degree of ULF too. But I don't need flat to single digits, nor do I plan to make my system sound crappier by artificially boosting the bottom excessively for bragging rights on the forum to say I'm "flat to 8hz" or any of that nonsense that goes on around here. I'm most interested in actual sound quality at the LP and I full realize that 15hz is "enough" to get what I want without over-driving and stressing my amps, drivers and all that. I'm somewhat reasonable in my expectations for both SPL and ULF and realize it's a trade off between them, especially when you are limited on budget. I'm hoping to maximize value first and foremost. I don't have a strict budget, but let's just say it's like a firm $2000 in drivers so we can all stay on the same page. No limit on wood, glue, screws, build difficulty, effort or time required, or space consumed.

My initial thought before I learned about the phase issues of mixing ported with sealed with horns was this:

4 horns (high passed where appropriate)
4 ported subs tuned at 14hz
8 infinity 1260's sealed in each column base for "smoothing subs"

Each sub or bank of subs/amp would be fed an output from something like a miniDSP. I'm not super knowledgable about these yet (I'm going to buy one this week and just play around with it) but I'm generally strong at learning stuff like this.

As I started to learn more doing the research for this project I realized that mixing different types of subs might not be a good idea. So now I am wondering if I stick with the plan, and if I do how would I theoretically integrate all that ? Or should I abandon the plan and do something else?

My backup plan was to just start with 4 ported subs (think marty style) in a custom designed box. I'm fairly comfortable using WINISD to design a ported box, tune it, build it etc.. this part isn't too scary for me. Then just add on more as funds allowed over time.

The two most important things to me are: #1- VALUE. The maximization of the ratio of how much bass and the quality of that bass to the cost. and.... #2 -UPGRADE PATH. I want my solution to have a clear option to add more over time to get really excessive and stupid with it. I can't afford that now, but years from now.. who knows? I'd like my solution to have this in mind so if 5 years from now I want to add more I can.

Suggestions ?

One idea I had was to fold some monster horns under my riser. My riser probably would be 16 feet long by 23.5 feet wide, basically the entire back half of the room. I could go 10 foot walls to begin the soffit and 12 foot in center if I had to do it, if I needed a little extra riser height for something crazy. Could I fold 8 crazy horns in this space? Or 6? 4?

I'm really only interested in going this route if it can be over the top. Otherwise, it's not worth the trouble to me. I'm ok using the attic space above the room too if needed, and I can fit a horn that's 6 feet tall and 4 feet wide behind my screen wall (I could fit a couple or more actually) but my problem is designing something like that. My hornresp skills are lacking, but again I'd be willing to learn.

The design that interested me the most is the GHORN so far. But I also had an idea of tuning higher (seems like that works with horns well) and then HPF the horns to remove ULF and use a low tuned ported sub for that. I'm debating if it's better to tackle this project from that angle and worry about the miniDSP settings to mix a 14hz tuned ported subs with higher tuned horns -or- If I should just use the available space I have and I am willing to use for a horn that's just bigger and tuned lower ??

I don't have a serious preference for one kind of sub over the other but generally I've favored the sound of a horn. It just sounds better to me, clean, effortless, high efficiency, low distortion. Plus it seems like when you pound a horn you don't hear the mechanical distress because the driver is burried inside, where as with sealed or IB you do as soon as the driver protests, especially when you chase single digits loud. Ported at tune and near it always sounds great to me too, but away from tune sometimes they seem muddy to me, at least compared to that super clean bass from a horn. So I guess I favor horns slightly, and I'm a tad biased against sealed and IB because they aren't loud enough and the ULF extension doesn't translate well in real life as being impressive. It's mostly for bragging rights with a chart, which isn't at all my goal. I want to shake chair apart and scare people with a demos. I won't listen that loud, but I'd like to be able to show off when I want.

WHAT SAY YOU? Am I just crazy ?
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post #2 of 411 Old 07-26-2014, 09:05 PM
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OK to start off, what is the cubic feet of the space and how much room do you have available for sub-duty?
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post #3 of 411 Old 07-26-2014, 10:40 PM
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129db at 17hz 2 pi space.


8.0' H x 3.0' W x 4.0' D


back of the envelope concept of internals





I haven't done an exact path length calculation, but eyeballing it I guesstimate about 24 feet long, which would give a tuning of about 19hz and a low corner -3db of about 17hz.


it equates very roughly to about 4 si ht 18 large ported cabs tuned similarly on the low end and about 8 of them on the upper end.


numbers are based on the uxl 18 driver, but we may be able to find something that works that costs less, perhaps even a pair of drivers.
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post #4 of 411 Old 07-26-2014, 11:48 PM
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lilmike had noted that the alpine sws-15 worked well in a horn, I forget which one.


I modeled it up. after making a few adjustments here and there...my initial reaction was...you got to be kidding me!


the response is among the best that I have ever seen in a front loaded horn.


[EDIT: after looking at this again, my initial conclusion may have been driven as much by the sheer size of the horn and the positive effect that has on response as the driver itself.]




max spl is 'only' 127 db in the excursion limited zone at 15mm xmax, but unlike most drivers in the ultra budget category, this little guy has a damage point of 30 mm. the street price on the driver is something like $120.


mike, i think that we may have found what you are looking for!
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post #5 of 411 Old 07-27-2014, 05:32 AM - Thread Starter
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Whoah! That's what I'm talking about! Tell me more!

Tell me MOAR!

Can I see the hornresp screens, the details ..dimensions ...? That looks good so far! THANK YOU!

Also, with such a cheap driver does it make sense to double them up (drivers) since wood costs more than the driver ?

Big difference with a better driver or not ? Could I mix drivers ? (Like a few UXL and a few Alpine ? ) and then swap out the alpine at later dates as an upgrade path ?



Quote:
Originally Posted by martinq View Post
OK to start off, what is the cubic feet of the space and how much room do you have available for sub-duty?
The room is 36 feet long by 25 feet wide with about an average of 9 foot ceiling.

I'm guessing about 8000 cubic feet ?

I'd say keep each sub to a practical size of a sheet of 4x8 cubed. But I guess it could be more if it was worth it.

I'd likely design into the room, I won't have an ugly black box visable. I have about 3 feet behind my screen wall. I could corner load a pair in the back and make look like the back wall or fancy vaneer and trim. I can adjust things if necessary my room isn't being built for another 3months.

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post #6 of 411 Old 07-27-2014, 06:15 AM
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This is what a ultimate bass thread should be. Massive horns

I'm planning on doing something like you are, but I am on the opposite side of things. I am space limited. I have my bass horn already for above 40Hz, planning out the below 40Hz option. I used to use 4x ported 21s above 35Hz with 2x DTS-10s below it, I could get it integrated well on measurements but I wasn't happy with it, I like the sound of a FLH over any other design and that is what I am trying to go for. However I much preferred the DTS/21s operating over different bandwidths than them operating over the same bandwidth above 35Hz.

I would recommend that you don't overlap the operating bandwidth of different designs, dedicate each type of sub to a specific bandwidth. It does feel like you are wasting SPL but IMO it is subjectively better this way. I will also offer this, build your system/upgrade path to to be able to play 10db over the highest required SPL at the LP.

I also agree about sealed and ULF and all the chest beating and bragging around here with the graph obsession, people are entitled to their opinions and mine aligns with yours on this matter, ULF is much ado about nothing. I have never been impressed with a sealed system, they just sound and feel weak. I think the fact that notnyt changed from his 8x sealed LMS to ported and Luke from his 4x sealed LMS to THs is evidence enough for those who do not have the experience themselves.

I wish I had the kind of space you have. Will be watching this.

This thread may be of particular interest to you -

http://www.hometheatershack.com/foru...ut-please.html

All the best!
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post #7 of 411 Old 07-27-2014, 06:26 AM
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That guy did an amazing job on his theater room. Horned bass for everything below 200hz. And lots of them.
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post #8 of 411 Old 07-27-2014, 06:31 AM - Thread Starter
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Quote:
Originally Posted by Decadent_Spectre View Post
This is what a ultimate bass thread should be. Massive horns

I'm planning on doing something like you are, but I am on the opposite side of things. I am space limited. I have my bass horn already for above 40Hz, planning out the below 40Hz option. I used to use 4x ported 21s above 35Hz with 2x DTS-10s below it, I could get it integrated well on measurements but I wasn't happy with it, I like the sound of a FLH over any other design and that is what I am trying to go for. However I much preferred the DTS/21s operating over different bandwidths than them operating over the same bandwidth above 35Hz.

I would recommend that you don't overlap the operating bandwidth of different designs, dedicate each type of sub to a specific bandwidth. It does feel like you are wasting SPL but IMO it is subjectively better this way. I will also offer this, build your system/upgrade path to to be able to play 10db over the highest required SPL at the LP.

I also agree about sealed and ULF and all the chest beating and bragging around here with the graph obsession, people are entitled to their opinions and mine aligns with yours on this matter, ULF is much ado about nothing. I have never been impressed with a sealed system, they just sound and feel weak. I think the fact that notnyt changed from his 8x sealed LMS to ported and Luke from his 4x sealed LMS to THs is evidence enough for those who do not have the experience themselves.

I wish I had the kind of space you have. Will be watching this.

This thread may be of particular interest to you -

http://www.hometheatershack.com/foru...ut-please.html

All the best!



Hi, Thanks for the comments and link! I'll give that link a read; I don't go over to HTS too often myself so I appreciate that.

I've never been impressed with a sealed system either. Granted I've not listened to a 32 driver system, but I can't afford 32 drivers anyways. My issue with IB and sealed is as soon as you chase single digits and "flat" you get poor sound relative to a horn. The distortion rises, the output capability drops, the amps heat up, the driver goes into distress quicker and the when it does you can hear it (and it sounds bad). Nothing is worse than mechanical limits being heard over your bass. Even when you pound a horn you don't generally hear that stuff, and the effortlessness of it is something magical. I think IB and sealed can be great solutions for small air tight rooms or those who don't have a serious SPL requirement but in a big space and a big appetite for excessive they fall short. It's funny you mention the conversion by some of the big dogs to ported or horns because I've read the archives and those were a few of the main reasons for my line of thinking. Notnyt has offered me some advice which I took and appreciated regarding ported, which is why a ported set up like his (but with cheaper drivers and spread out around the room more) is my backup plan or option #2 .

Ported at teens (think 16hz) is a good option for me. 4 of the UXL should do some damage and I can add more for SPL. One of the things I wondered was how much does different tuning effect things. Like for example if I tuned the first 4 at 16hz, but added 4 more tuned at 14hz would that be a big deal ?

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post #9 of 411 Old 07-27-2014, 06:38 AM - Thread Starter
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Quote:
Originally Posted by chrapladm View Post
That guy did an amazing job on his theater room. Horned bass for everything below 200hz. And lots of them.
mwmkravchenko seems to be dishing a lot of good advice in that thread. I'm liking it.

"I have done quite a few horn loaded subs that should have had built in echo according to the naysayers. But the effects are very difficult to hear in the low end. Horns done well have vanishingly low distortion. In fact I have yet to have heard one that I found to be problematic in any way. "

I'm liking reading that too ^

"Last bit of advice. Your ULF sub would be better as a FLH (front loaded horn) I can always tell the sound of a tapped horn. I never really enjoy them."

Ok- So I gotta ask what exactly is the difference? (Ok I get the actual physical difference of the driver mounting and all that, but why would the sound be different?)


"For a sub you want a woofer with a much lower Qts.
It is a basic thing in that a lower Qts driver means it is a stronger driver."



Another gem of wisdom. Not sure I understand why though....

A horn is a balancing act of motor strength versus the compression wave you want to force down the horn path. The stronger the motor the better the control over the way the cone moves. A proper horn is a very hostile environment for a woofer compared to a vented box or a sealed box. There is quite a bit of pressure generated on the cone. The rear chamber should be sized in such a manner that it provides a restorative force to the driver. A balance of pressure. The very large Chambers you propose will have very little of any spring or restorative force to keep the driver in check. The front of the driver will see a high pressure whereas the back will not. A great invitation to nonlinear behavior. That's a fancy word for distortion.


Ok.. I am starting to get it.


"There should be an open space in between the driver and the opening into the horn. As in a empty space 24.5 mm deep by 1090.32 cm^2. Then off of this empty space you punch your hole into the horn and voila, you get you beginning. This beginning has to be the very start of the horn, it cannot tap it from any other point along the horn path."



Keep in mind that those graceful curves need only be approximated with angled reflectors. In a bass horn an angled reflector is actually preferred over a curve. you don't want to be reproducing midrange frequencies out of a bass horn, and the flat reflectors help to knock them down acting as a natural filter.


Remember that within a horn the air is compressed, and behaves more or less like a fluid. Smooth paths create less turbulence.
Less turbulence equals a better functioning horn.



Liking that thread so far... lots of good stuff. Learning a lot. I've yet to actually follow a noob start a horn and get schooled figuring it out. That's the secret sauce I was missing, in my attempt to understand things I think. I probably still have a lot of errors to make but I feel like I am making progress. I'm excited to see the numbers LTD02 was working with and mess around just for reason of learning. His design earlier really has me intrigued.

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post #10 of 411 Old 07-27-2014, 07:15 AM
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I agree with a lot of your comments, the direct radiating designs can't do what a horn does, precisely why I don't know. For me it isn't just the sound but a FLH has sheer brute force to it that you feel differently and that matters to me a lot. The dynamics and effortless presentation are definite trademarks of a FLH. I will note that I personally am not fond of THs after having experienced the DTS-10.

I'm not the expert on designing horns but from my understanding a TH generally has more frequency and time domain issues compared to a FLH, in turn a TH of equivalent size will be louder around tuning and will has less of a dropping response. The extra problems are caused by the driver being loaded on both sides of the cone, a FLH has a sealed rear chamber so it only uses one side of the cone.

Low Q means the motor controls the cone better, it can aid in fighting against the usually small rear chambers of a FLH where a weak motored driver would have difficulty.

Ported would be a good choice if you are looking to maximize the 15-30Hz bandwidth SPL for a given size, but the FLH would be a lot more enjoyable subjectively IMO. With enough size and enough horns you would not be giving up anything, anywhere above 15Hz, if anything you'd have among the best systems out there. The key problem in this equation is always space. If you use enough FLHs you can get the 5Hz stuff too (with EQ and if you desire of course) as the system is basically behaving like a sealed enclosure below the tune. The JTR OS LF is an excellent example of this and has been well reviewed by all who have heard it. Room gain combined with a high excursion driver in a FLH with a sealed chamber is what allows the OS LF to be effective at 5Hz, if you have enough of them it is basically behaving like a single high excursion sealed 18 at 10Hz, just like any sealed system. People just buy the S2 or DIY sealed subs because they figure that enough sealed drivers will get them the SPL they need everywhere and there's no need for the FLH, but they ignore that the FLH has different characteristics that make a big impact on the subjective sound.

I think that a lot of FLHs (as many as you can fit) using the Alpine driver John suggested would be a good way to go, the thread I linked is also doing what you want to do so you may pick up good ideas or designs from there as well. Mark is a smart guy and he does consulting for Funk Audio. He is a member on AVS and maybe he will chime in.

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post #11 of 411 Old 07-27-2014, 07:27 AM
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Mfusick,

Why don't you model, fold, and build your own horn? The tutorials are out there. Learn to use HornResp, learn to use Sketchup, and in a very short time you could actually DIY this thing. There will be folks who will pitch in when you get into a bind. I just don't like the "please design this for me" threads nearly as much as the folks who document their own designs and builds....

What LTD02 has posted above will work, ONLY in multiples, and ONLY if that is a1pi or 2pi simulation.

How can you have an unlimited budget for wood and materials, but limited otherwise? Just curious...

Ask someone who has actually measured the Alpine 15" for proper T/S specs (lilmike would be the first person I ask, or search the archives for an alpine horn build), plug them into HornResp, and post up what you get....You can get some pretty good advice then.

JSS
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post #12 of 411 Old 07-27-2014, 07:29 AM - Thread Starter
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Quote:
Originally Posted by Decadent_Spectre View Post
I agree with a lot of your comments, the direct radiating designs can't do what a horn does, precisely why I don't know. For me it isn't just the sound but a FLH has sheer brute force to it that you feel differently and that matters to me a lot. The dynamics and effortless presentation are definite trademarks of a FLH. I will note that I personally am not fond of THs after having experienced the DTS-10.

I'm not the expert on designing horns but from my understanding a TH generally has more frequency and time domain issues compared to a FLH, in turn a TH of equivalent size will be louder around tuning and will has less of a dropping response. The extra problems are caused by the driver being loaded on both sides of the cone, a FLH has a sealed rear chamber so it only uses one side of the cone.

Low Q means the motor controls the cone better, it can aid in fighting against the usually small rear chambers of a FLH where a weak motored driver would have difficulty.

Ported would be a good choice if you are looking to maximize the 15-30Hz bandwidth SPL for a given size, but the FLH would be a lot more enjoyable subjectively IMO. With enough size and enough horns you would not be giving up anything, anywhere above 15Hz, if anything you'd have among the best systems out there. The key problem in this equation is always space. If you use enough FLHs you can get the 5Hz stuff too (with EQ and if you desire of course) as the system is basically behaving like a sealed enclosure below the tune. The JTR OS LF is an excellent example of this and has been well reviewed by all who have heard it. Room gain combined with a high excursion driver in a FLH with a sealed chamber is what allows the OS LF to be effective at 5Hz, if you have enough of them it is basically behaving like a single high excursion sealed 18 at 10Hz, just like any sealed system. People just buy the S2 or DIY sealed subs because they figure that enough sealed drivers will get them the SPL they need everywhere and there's no need for the FLH, but they ignore that the FLH has different characteristics that make a big impact on the subjective sound.

I think that a lot of FLHs (as many as you can fit) using the Alpine driver John suggested would be a good way to go, the thread I linked is also doing what you want to do so you may pick up good ideas or designs from there as well. Mark is a smart guy and he does consulting for Funk Audio. He is a member on AVS and maybe he will chime in.
I did PM him a quick link here.... I certainly would not mind some input from him

Another quote of his:
"The other great thing with proper horns is the low overall impedance peak that you get. Much easier load on the amplifier. Compared to a vented or sealed enclosure. Ther's a reason why horns rule.

You know other than really low distortion, almost unlimited dynamic range, punch, etc."


I've kind of always felt this way ever since I heard my first horn, but I never really understood why. Reading more and more it's staring to make sense.

The magic ingredient is execution and with horns there's a lot of room for error there, where as sealed subs any coward can build one. It's certainly not a "safe" way to travel to the kingdom of bass, but if you make it you are rewarded heavily upon arrival.

On another note from that thread,

Whoah! Another idea... I could use smaller cheaper drivers like the infinity 1260 in my columns for smoothing subs but fold them inside the column. (instead of sealed) Like Tsolm (I think that's his name here) did with a tall but not too folded design for those.

GENIUS!


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post #13 of 411 Old 07-27-2014, 07:47 AM - Thread Starter
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Quote:
Originally Posted by maxmercy View Post
Mfusick,

Why don't you model, fold, and build your own horn? The tutorials are out there. Learn to use HornResp, learn to use Sketchup, and in a very short time you could actually DIY this thing. There will be folks who will pitch in when you get into a bind. I just don't like the "please design this for me" threads nearly as much as the folks who document their own designs and builds....

What LTD02 has posted above will work, ONLY in multiples, and ONLY if that is a1pi or 2pi simulation.

How can you have an unlimited budget for wood and materials, but limited otherwise? Just curious...

Ask someone who has actually measured the Alpine 15" for proper T/S specs (lilmike would be the first person I ask, or search the archives for an alpine horn build), plug them into HornResp, and post up what you get....You can get some pretty good advice then.

JSS

Hey Max ! Thanks for dropping in and your feedback! Your are so right about most of everything you said.

First, I agree with the "design this for me" attitude. Trust me I am a DIY at heart. That is why the thread title said "need help designing" and not "design for me" I very much want to learn myself, tweak myself, and understand what is going on. But this is new to me and I'm by no means ready to venture at it solo.

Truth be told I've not yet put quite enough time in to learning and understanding this stuff, messing around with HORNRESP and all that. I'm currently "in progress" doing that. Hopefully everyone will bear with me as I venture down my learning curve and provide me assistance when I need it. That's exactly what I am looking for!

One of the reason why I asked LTD02 for a bit more info was I wanted to start with what he was working with and mess around, reverse engineer, and just plain LEARN. I'm not sure you can start a thread asking for a "serious" bass solution and consider folding 8 or more bass horns and building them yourself without some level of DIY commitment I'm committed and I've got time to learn and perfect. Like I said I am only interested in going down this more difficult and space consuming road if it could be AMAZING and over the top. I'm not at all interested in "average" I'd rather just design up 4 ported cabs for some UXL18's and call it a day. (when did 4 UXL ported at 16hz become average ? lol! )

$2000 in drivers seemed like my upper limit. I don't have unlimited funds in wood, but since I am doing an entire home remodel during this project and the my theater space is 35 feet long and 25 feet wide I can sneak 10 extra sheet of ply and 20 tubes of PL premium past my wife a lot easier than I can sneak a tractor trailer delivery full of subwoofers past her ! Plus this is an investment into my theater space and my personal hobby that will pay dividends for years and years. That's value, even if it costs me $1000 in materials and a couple months of time building it all out.

My budget is probably a bit under the top class around here, but my commitment and passion is top tier. I'm hoping that with some creativity and personal commitment and effort/skill/luck I can reach the golden kingdom of unobtanium bass without just writing a check. Keep in mind I might not always be poor, or have a wife out of work with kids so again the upgrade path is important to me too. This isn't a fly by night hobby for me. I'm generally not scared either. Imagine if you could remove every obstacle from bass solulution design that pops up except the cost of gear, how far can you push the envelope ? That's my goal! My entire theater is being designed and constructed with "VALUE MAXIMUS" in mind, in fact that's probably the leading name for my build so far. I want big theater experience on a small budget.

EDIT: I did PM lilMike but he's also busy doing a remodel

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Idiot moment: Would folding a horn with (2) 24" SI subwoofers be idiotic? Or awesome ?
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Help is on the way.
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Quote:
Originally Posted by Mfusick View Post
Idiot moment: Would folding a horn with (2) 24" SI subwoofers be idiotic? Or awesome ?
I think the ratio of motor-strength to piston area is too far outside optimal.

Take a good look at the 4-ohm LAB15 special on ebay. I think I'd grab a dozen or so if I was in the US.
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Quote:
Originally Posted by martinq View Post
I think the ratio of motor-strength to piston area is too far outside optimal.

Take a good look at the 4-ohm LAB15 special on ebay. I think I'd grab a dozen or so if I was in the US.
Eminence driver sale
There seems tons of available drivers in these ranges that might work (like the Alpine LTD02 suggested) but I'm still learning what to look for in a driver.

With drivers like THIS I could easily fold up 8 horns in my riser, even more behind screen wall or back etc... There is strength in numbers with bass drivers so 8+ could get scary !

My struggle is balancing and integrating things. I can do a loud horn, but give up ULF. I can do a ULF chasing build but give up SPL. Or I could do both (either up front or in 2 phases) but integrating them seems cumbersome. Not sure what to do

Needless to say.. I am devouring all this info provided. It's all appreciated. Keep it coming!

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Quote:
Originally Posted by Mfusick View Post
Idiot moment: Would folding a horn with (2) 24" SI subwoofers be idiotic? Or awesome ?
~250cuft each 500cuft total; I have toyed with it...138dB from 14Hz on up, but natural horn+large Le driver rolloff starting around 80-90Hz (no free lunch in audio). You start running into problems with very large folded horns. Once a fold segment gets longer than 5 feet, without PROPER 45 deg reflectors (only 90deg or less bends apply once segments get this large, unless you are willing to give up a lot of cu footage to reflectors), you get cancellations under 120Hz. Proper 45 degree reflectors take up more cu footage, and can make folding a nightmare, with lots of unused space in the cab. A proper 45 degree reflector means that the entire wavefront 'sees' the reflector, not just the 'outer half'. Bruce Edgar talked about this in an article titled "The Monolith Horn".

http://volvotreter.de/downloads/Edgar-Monolith-Horn.pdf

Look at all the other articles on this page, good stuff.

Too bad Bruce Edgar didn't have HornResp or Sketchup at the time....

Once you get proper T/S parameters for the Alpine, plug into hornresp and see what you get. The Loudspeaker Wizard tool in HornResp is very useful. Look at the old tutorial for an OD horn, and post up what you come up with. I would use a compression ratio of 2.5 or less. The lower in freq you want to go, or the larger the driver, the lower the comp ratio should be, as a rule of thumb.

JSS
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post #19 of 411 Old 07-27-2014, 09:11 AM
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Quote:
Originally Posted by martinq View Post
I think the ratio of motor-strength to piston area is too far outside optimal.

Take a good look at the 4-ohm LAB15 special on ebay. I think I'd grab a dozen or so if I was in the US.
Eminence driver sale
Make sure you get the T/S params before purchasing, as this was a one-off run.

JSS
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post #20 of 411 Old 07-27-2014, 09:26 AM - Thread Starter
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OK, thanks !

I am starting to get it. Hopefully someone can really walk me through it right here and it should fully sink in. Let's take a look at two modest similarly priced drivers (nothing too crazy)

INFINITY 1260 @ $63
SPECS:
http://dk.infinitysystems.com/tl_fil...260W_PI_EN.pdf

and,

DAYTON 12" PRO WOOFER @ $65

Is there something notably different between one or the other that makes it better or worse suited for use in a front loaded horn ?
If so what is it ?

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Back of the napkin calcs using Lab15 posted T/S (not this batch, but the normal ones):

Eight Lab15s in ~35cuft horns with 4000W of power total = 143dB from 19Hz on up at Xmax, rolloff below, but doesn't reach Xlim, even without highpass. That's enough for the largest of cinema auditoriums out there, a full 115dB at over 25m away. If this doesn't break things in a neighbor's house, nothing will.

But again, tradeoffs. Limited clean ULF (10Hz is 120dB, but 6mm past Xmax). But great extension into the midbass, natural rolloff around 150Hz.


Tradeoffs, tradeoffs....

The Lab15 would be a great driver to outfit a cinema with, both to augment the LF in the mains as well as to provide LFE. It doesn't like a tune below 20Hz in a horn, though (with published factory T/S specs).


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post #22 of 411 Old 07-27-2014, 09:43 AM
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The Infinity 1260 works well in a slim THT. Lots of SPL down to ~22Hz, maybe a tad below depending on the room.

JSS
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post #23 of 411 Old 07-27-2014, 09:48 AM - Thread Starter
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THT is ?

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post #24 of 411 Old 07-27-2014, 10:03 AM
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the response posted in #4 uses 2 alpine sws15 drivers.


they are about as cheap as drivers get, but have 15mm xmax, 30mm xdamage, one way, and like I mentioned are only ~$120 ea.
the surprising thing is that they actually work in a horn...and VERY well it would appear.
compression ratio is that horn is about 4:1. my understanding of that driver is that it has a pretty robust surround and cone too, so it may actually survive horn loading.
the model is for 2 pi space (which is like measuring out in a field), so you should get some room loading/boundary gain, but even if not, it is still awesome.
that horn is 4'x8'x3'. it could be redone using more wood into two horns that are 4'x'8'x1.5'.
max spl in the excursion limited region is ~127db at 15mm. the uxl driver shows about 131.5db at 34mm in the same region.
two horns give +6db btw, at least in some theory.
given the way that you described your budget scenario, it would make more sense to double up the dual sws15 horn vs. moving up to the uxl driver.
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post #25 of 411 Old 07-27-2014, 10:06 AM
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"THT is ?"

not what you want. bfm front loaded horn with a driver minimum excursion point of around 28-30hz. that is 8-10hz higher tuning that what you want, at least.


...


the lab 15 driver is a great driver, has about the same excursion as the sws15, and costs about twice as much.


how would it be better than the sws15?
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that is 1 watt in 2 pi space. to keep comparisons comparable, if anybody else posts a response graph, please change the voltage to reflect 1 watt. in this case the drivers re is 1.8 and hornresp is configured for 3 in parallel, so voltage is set at 0.77 volts. it doesn't matter how they are configured series or parallel, just ensure that responses posted are for 1 watt. otherwise it will all just be confusing.

max spl is similar to the dual sws15 configuration, 127db.*


* note that the infinity specs understate xmax, as the spec is for voice coil overhang only. adding 1/3 of the gap high to the coil overhang gives about 16mm xmax.
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the Dayton 12" with 5mm xmax is completely out of the question. it may work, but will have something like 9db less max spl in the excursion limited zone as these other configurations.

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post #28 of 411 Old 07-27-2014, 10:59 AM
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So, I got invited to the party, but I've got no real time to play along at the moment.

Fundamentally? If you have the space and the budget, you can get the bass you want a bunch of different ways. It's all in what you want when you're done.

Horns (either tapped or front-loaded)? For an honest 125 dB at the seats without sounding strained, I'd start with 4 in that space, each loaded with a capable driver or a pair of decent drivers. The original pair of LilWreckers at full throttle in about half of your planned space was certainly an experience.

Ported? I'd start with a minimum of 8 elite drivers, 16 lesser ones. NotNyt has capably demonstrated this path.

Sealed? With the same number of drivers, things will be pretty much the same as ported, after EQ, but it depends on the SPL you want at your desired low corner, because you will run out of excursion and power handling sooner. NotNyt has "been there and done that", and upgraded.

Total cabinet volume will be similar for the horn and ported options, sealed will be less total volume, but will roll off sooner.

Power? Depends on the type and number of drivers, but the horns will likely require less total power (or you did it all wrong and wasted a LOT of plywood and time).

Tapped vs Front-loaded? Look at where the first excursion peak falls below the -3 dB point. I prefer tapped horns for low tunes in a home theater setting, they're a bit more forgiving, as the low corner is an excursion minima, not an excursion maxima.

As far as "hearing" a difference? Not going to argue that, there is no point. Personally, I find the sound (and distortion characteristics) of my front-loaded horns more objectionable when compared to my tapped horn designs operating in a similar bandwidth, but my ears don't matter in your room.

To each their own. Your ears, your room, your perception as to what it should sound like when you're done.

My ears, my room, and my goals? My theater is a LOT smaller (~12 X ~17) than what you're working with. Though my plans may change as I learn of new driver options, I'm currently planning on using two large, low-tuned tapped horns, each loaded with a pair of beefy 15s and fed a couple of kilowatts. No, they're not designed yet. It will be a while, as my theater currently looks like this (and the rest of the house isn't much further along...).

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Last edited by lilmike; 07-27-2014 at 11:05 AM. Reason: typos and clarification
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post #29 of 411 Old 07-27-2014, 11:15 AM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post
the response posted in #4 uses 2 alpine sws15 drivers.


they are about as cheap as drivers get, but have 15mm xmax, 30mm xdamage, one way, and like I mentioned are only ~$120 ea.
the surprising thing is that they actually work in a horn...and VERY well it would appear.
compression ratio is that horn is about 4:1. my understanding of that driver is that it has a pretty robust surround and cone too, so it may actually survive horn loading.
the model is for 2 pi space (which is like measuring out in a field), so you should get some room loading/boundary gain, but even if not, it is still awesome.
that horn is 4'x8'x3'. it could be redone using more wood into two horns that are 4'x'8'x1.5'.
max spl in the excursion limited region is ~127db at 15mm. the uxl driver shows about 131.5db at 34mm in the same region.
two horns give +6db btw, at least in some theory.
given the way that you described your budget scenario, it would make more sense to double up the dual sws15 horn vs. moving up to the uxl driver.

So what changes would need to accommodate dual drivers per horn cabinet ?

I like idea of splitting the depth for under riser but doubling it behind screen

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post #30 of 411 Old 07-27-2014, 11:35 AM
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"So what changes would need to accommodate dual drivers per horn cabinet ?"


for a dual driver cab (at least in this one where there is ample space) the drivers just go side-by-side. so no changes are required.


if splitting the cabs in two, it would be best to keep their mouths co-located.

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