OT content deleted, as a reminder, please read and follow the Forums rules if you have forgotten them.Had a quick look. Ignoring the commercial source, the distances are enormous and the variations in sound seem pretty tepid (even if the variations in colour are truly eye catching)... if you have a close look at the db scale and read the piece critically.
Once again, wannabee-engineerng fallacy of letting your eye do the hearing.
B.
Rog Morale and Void Acoustics are not "wannbe engineers". They both have customers that use arrays and this article is meant to help them wisely choose how to best accomplish that.
The distances range from 1 meter spacing to about 24 meter spacing, so pretty close to the distances we have been talking about in this discussion. And those eye catching color variations are very audible. It's not just a colorful blip on a screeen you have to read the text as well. Quotes like this can't be denied. This quote appears right before figure 47 and 48 at the bottom of page nine -
SPL deviations of up to 8 dB would be evident by taking one step forwards or backwards around a lobe.
This is exactly what I have been saying, it's very audible.
You can bury you head in the sand and try to ignore the full technicolor images and the associated text that clearly says it's a huge problem but every time you say it I'm going to be right behind you with the proof that says you are wrong.
The distances range from 1 meter spacing to about 24 meter spacing, so pretty close to the distances we have been talking about in this discussion. And those eye catching color variations are very audible. It's not just a colorful blip on a screeen you have to read the text as well. Quotes like this can't be denied. This quote appears right before figure 47 and 48 at the bottom of page nine -
SPL deviations of up to 8 dB would be evident by taking one step forwards or backwards around a lobe.
This is exactly what I have been saying, it's very audible.
You can bury you head in the sand and try to ignore the full technicolor images and the associated text that clearly says it's a huge problem but every time you say it I'm going to be right behind you with the proof that says you are wrong.
Some of the widely-spaced array examples in the 'Practical Guide to Bass Arrays' are pretty damming to say the least. Not only have you been saying it all along, but you've clearly been right all along. . . I would’ve been very disappointed had I built my bass horns 60 feet apart, and killed my sound field through severe comb filtering. . . .
So after reading up on this subject a bit more, my bass horns should be side-by-side (in-line, horns on parallel axis), and specifically NOT towed in. . . I might even benefit from delaying the outer horns a few milliseconds from the inner – which has the pseudo-effect of positioning my horns on a convex wall – and specifically NOT a concave wall. This makes complete sense to me, as the narrow angle-of-inclination will encourage expansion of the sound field – in a constructive fashion.
Establishing a focal point for my bass horns was a really bad recommendation (almost deceitful) – shame on you weltersys. . . And shame on me for thinking you were actually trying to help . . . Not cool.
What I would really love to do is find out what software Rog was using and sim your plans (almost) exactly. As I've mentioned many times the Direct software can't simulate the intense beaming of your large horn (although we can make some educated inferences about the effect).
According to Rog's quote this software is EXACTLY what I'm looking for, what I've asked about four times now.
... the simulations shown in this guide were made with all the test enclosures physical and technical parameters taken into account. The simulation software is not only aware of where the enclosure is located, but also knows its radiation pattern at all relevant frequencies. Detailed polar plots were made of the real test enclosure, these as well as the enclosures physical and technical properties were used as the bases for all simulations.
If I could sim your horn and take the Hornresp polar and input it directly into this software this would be just the ticket. The only remaining problem is that the Hornresp polar won't be exactly accurate compared to what you are going to build - Hornresp assumes an axisymmetric (round) horn with a round mouth, which is a bit different than what you will be building. Still pretty close though.
Usually articles like that state the tools and software used at the beginning or in footnotes at the bottom but not in this case. If anyone knows what this software is please let me know.
In the meantime I'm going to actually read through the whole article (and it also refers to a Part II article) and read through Bob's other link for clues to appropriate software. If that yields nothing I'll do a search for appropriate software that will accept actual polar data.
If I do find software but it won't accept polars it will probably accept .frd files, in which case I'd need detailed .frds, which I can make, but which Hornresp doesn't provide for off axis points. In that case maybe David McBean could be persuaded to allow Hornresp to show off axis virtual mic positions. I'm guessing it might be possible since the Directivity tool allows for response, pattern, beam width and polar maps.
In my experience simulators are an incredibly useful tool and can be uncannily accurate if you actually sim accurately and sim an actual reflection of what you are going to build. The Direct software gets us in the ballpark but software like Rog used in that article could get us right on the pitcher's mound.
If we can get this simulated to a high degree of accuracy there will be very little messing around, it will be plug and play as soon as it's built. The software can show exactly what's going to happen and you can optimize for each speaker's position and delay before building anything.
I'm still leaning heavily towards a single mono sub but with the proper software I can probably dial in something something just as good (or at least almost as good) with any layout you choose.
I'm probably going to be working long hours for the next few days but I don't sense any particular rush so hopefully I can find appropriate software, learn to use it and get it loaded up with proper files in the next few weeks.
According to Rog's quote this software is EXACTLY what I'm looking for, what I've asked about four times now.
... the simulations shown in this guide were made with all the test enclosures physical and technical parameters taken into account. The simulation software is not only aware of where the enclosure is located, but also knows its radiation pattern at all relevant frequencies. Detailed polar plots were made of the real test enclosure, these as well as the enclosures physical and technical properties were used as the bases for all simulations.
If I could sim your horn and take the Hornresp polar and input it directly into this software this would be just the ticket. The only remaining problem is that the Hornresp polar won't be exactly accurate compared to what you are going to build - Hornresp assumes an axisymmetric (round) horn with a round mouth, which is a bit different than what you will be building. Still pretty close though.
Usually articles like that state the tools and software used at the beginning or in footnotes at the bottom but not in this case. If anyone knows what this software is please let me know.
In the meantime I'm going to actually read through the whole article (and it also refers to a Part II article) and read through Bob's other link for clues to appropriate software. If that yields nothing I'll do a search for appropriate software that will accept actual polar data.
If I do find software but it won't accept polars it will probably accept .frd files, in which case I'd need detailed .frds, which I can make, but which Hornresp doesn't provide for off axis points. In that case maybe David McBean could be persuaded to allow Hornresp to show off axis virtual mic positions. I'm guessing it might be possible since the Directivity tool allows for response, pattern, beam width and polar maps.
In my experience simulators are an incredibly useful tool and can be uncannily accurate if you actually sim accurately and sim an actual reflection of what you are going to build. The Direct software gets us in the ballpark but software like Rog used in that article could get us right on the pitcher's mound.
If we can get this simulated to a high degree of accuracy there will be very little messing around, it will be plug and play as soon as it's built. The software can show exactly what's going to happen and you can optimize for each speaker's position and delay before building anything.
I'm still leaning heavily towards a single mono sub but with the proper software I can probably dial in something something just as good (or at least almost as good) with any layout you choose.
I'm probably going to be working long hours for the next few days but I don't sense any particular rush so hopefully I can find appropriate software, learn to use it and get it loaded up with proper files in the next few weeks.
BTW, thanks Ben for including me in your sig line once again. I actually like it, you've got more text about me in the sig line than about you. I guess you did get forced to remove the last iteration and this new wording is an attempt to insult without breaking the rules. As always though, if you weren't posting incorrect information I wouldn't have to correct it and there would be no need for this passive aggressive behavior.
I'm going to keep a collection of your various sig lines for posterity. It's a nice feeling to be so important to somebody.
Here's the one from awhile ago that was part of your sig line for months.
Here's the current one.
Unfortunately I didn't get a chance to grab the last one that you got rid of a few days ago since it was only up for 1/2 a day. Could you change it back so I can grab that one for my collection please? There were also a few iterations of that first one but I don't expect you to remember them all and that's the only one I grabbed at the time.
Also, in this new sig line you might want to include that when you say "working on motional feedback" you mean you've been talking about it for 8 years (since the day you joined the forum) and haven't actually done anything other than talk about it, and that your short lived position at Bell Labs was administrative in nature and had nothing at all to do with the research they did there.
EDIT - LOL, I didn't even notice your "hi fi aspirations" date changed from 56 to 57. Not quite sure, eh? But what's a year or two in 6 decades, I'm sure it's hard to remember.
Here's the one from awhile ago that was part of your sig line for months.
Here's the current one.
Unfortunately I didn't get a chance to grab the last one that you got rid of a few days ago since it was only up for 1/2 a day. Could you change it back so I can grab that one for my collection please? There were also a few iterations of that first one but I don't expect you to remember them all and that's the only one I grabbed at the time.
Also, in this new sig line you might want to include that when you say "working on motional feedback" you mean you've been talking about it for 8 years (since the day you joined the forum) and haven't actually done anything other than talk about it, and that your short lived position at Bell Labs was administrative in nature and had nothing at all to do with the research they did there.
EDIT - LOL, I didn't even notice your "hi fi aspirations" date changed from 56 to 57. Not quite sure, eh? But what's a year or two in 6 decades, I'm sure it's hard to remember.
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Eric,
1)"Your" bass horns polar pattern is far different than the typical front loaded or small bass cabinets used in multiple side-by-side-in-line-horns-on-a-parallel axis array.
"Your" horn dwarfs any used in the simulations or arrays you have seen.
I have measured, and compared the directivity of BR, FLH and TH a fraction of the size of "your" horn. You can see the results of those measurements in my threads. The "little" FLH "C Horn" and TH Keystone Sub show a fair amount of directivity at 100 Hz.
"Your" horn's DI will be several times higher than those "baby" horns.
You have specifically introduced a design element (a sub with a high DI) that may not be correct for your intended application (whatever that is has not been defined) and now plan to not point it at the preferred listening location.
I have no skin in this "game", but I do not understand why you would want to point a high DI sub at a place other than where the other high DI mid and high elements will presumably be pointed.
2) My recommendation was not "bad", I have set up focused arrays on many gigs where that goal made sense given the situation presented.
My recommendations are not deceitful, but you have not clearly understood the multiple ramifications of each and every one of them.
Just like JAG, you conclude my "recommendations" are useless, because you ignore key elements of my advice, then like some perverted version of a Socratic debate, allow yourself to follow the "post leader".
Because you still have not defined your sonic goals, you have no possible chance of achieving them.
Back when I did not realize that you would ignore 95% of the information presented you, I answered your questions with great specificity:
Wow, so many questions!
You are transitioning from an realm of audio where subjective differences in opinion on the validity of audio products are similar to the opinions of wine tasters, to the reality portion of the program- where results can now quite easily be measured and quantified for a fraction of the cost when I entered the "professional" (that means I was actually paid for my work) world four decades (plus several years..) ago. In fact, the free REW program allows anyone with a PC and a test mic with USB interface to perform audio tests that can't be done on equipment and software I have spent many thousands of dollars for over the decades.
1)The physics are fairly simple, an infinite spherical omnidirectional radiation is "full space", when restricted by a single boundary, known as "half space", the radiation is is confined and reflected from that boundary into a hemispherical radiation, the half portion of radiation that would be headed "down under" now can't, and is added going "upward", imparting a six dB gain.
Don't be frustrated- that's the simple part, the realities we deal with in the real world of sound reinforcement are not so cut and dried- the frontal area of a large speaker system is another boundary, large boundaries (and horns) have their own directivity index (DI), and the DI changes with frequency, size of the horn, and frontal area. All these factors combine to make a reality that does not conform readily to theories and simulations that don't exactly "reflect" the real world.
This thread will give you some "real world" results of a similar experiment that you propose:
PROOF-Whole vs half space sub loading
PROOF-Whole vs half space sub loading
In this thread I have linked some other studies of interest, especially the waveguide/horn extender thread, specifically applicable to your project:
http://www.diyaudio.com/forums/subwoofers/185588-keystone-sub-using-18-15-12-inch-speakers.html
Some specific answers to your questions:
Test 1: Expectations prior to a test will tend to influence what you will hear, the two horns will definitely sound different, whether one sounds "funny" depends on your sense of humor.
Test 2: Low frequency waves below around 200 Hz tend to be laminar, they flow like a liquid around objects, as such they are not affected by a ground surface, results are the same whether the surface is covered with asphalt, carpet, cement, grass or weeds. As the wavelength becomes smaller, it more resembles ray tracing, as in beams of light reflected from a mirror. Crushed basalt rock of 5/8" has large enough facets to just barely diffract frequencies as low as 1000 Hz, I would not hear that effect, but could measure it. The horns will still not sound alike.
Test 3:Again, the different horns will sound different. The negative implications for using a full-space horn adjacent to a planar surface would be comb filtering effects generated from the path length difference of the reflected vs direct sound, the benefits are increased forward directivity afforded by the virtual "line array" afforded by the ground plane "mirror image". As stated previously, that "mirror image" is dependent on the horn DI, the higher the DI, the less influence the ground plane has.
2) I stopped assuming others hear the same effects as I do even before noise induced 4kHz hearing loss and age related HF losses rendered my hearing incapable of hearing some fine details I could early in my career. That said, anyone that ignores the effect on DF speaker wire gauge makes is ignorant.
3) Back in 1982 I was using Crown, QSC and Yamaha amplifiers. I evaluated them against the dual toroidal power supply Crest P-3500 amplifiers and chose the Crest for it's superior sound quality. Through the years the various companies have produced and copied each other's many good and bad designs so many times that there is no easy answer to which is "best", though I can give some specific examples of "turkeys" from the roosts of Crest, Crown and QSC. As far as the "Pepsi Challenge", if you like the phosphoric acid edge of Coke, you won't be fooled by Pepsi. As far as I'm concerned, all decent amps sound alike, until pushed hard, what happens when they clip, limit, current limit or any combination of those, is what differentiates their sound in a hurry. The NU4-6000 happens to work better in virtually every metric other than fulfilling equipment riders than the QSC, Crest, and Crown amplifiers they replaced after some rather extensive testing a few years back.
4) Improper assumption, the worldwide market for LF horn drivers is larger than it has ever been. The B&C SW series, including the SW21152-4 21" driver with a 6" voice coil is an example of one "proper off-the-shelf horn driver", the high MMS is needed for the cone to remain linear when subjected to high compression ratios at the 4000 watt peaks the driver can effortlessly handle. Some of the other B&C SW series have lesser MMS/power ratios, and if you go by the old 1970 engineering references on the subject of horn design, you would choose them, and then be disappointed when the cones sound distressed when pushed to Xmax. The difference between the 1970's 50 to 100 watt drivers, and todays drivers that can handle 800 to 8000 watts is huge, think in engineering terms- if you put a Melroe Bobcat's shovel on a Caterpillar D9, it will be torn up in a hurry if used to mow down steel pylons, while the same shovel will last for years on the Bobcat if operated within reasonable expectations.
5) Nothing Don Keele has written is "essentially garbage", but there is a lot of experience he and others have shared through the years that does render some older papers obsolete in some respects.
On 6/16/16 Entropy455 asked this question in addition to the others above and below:
Bentoronto (and anyone else who may be quietly lurking) if I could please trouble you with two pointed questions:
6) Assume for the moment that you are getting paid (well paid) to completely design these horns for me (i.e. a hypothetical contract, in which you’d be tasked to completely design some quality outdoor full-size 20-Hz concrete bass horns). Question: before you even open a simulator, where would your years of experience guide you to begin? I.E. would you lean towards installing eight (or even more) 18” drivers into a massive throat as just-a-guy recommended? Or would you lean towards running a more traditional single 12” driver, or perhaps a single 15” driver, or even a few 12s - within a smaller throat? Where would your design experience take you?
6) My years of experience would dictate the first step in design would be to collect a cash retainer of a minimum of 25% of the hours I would estimate needed for the design, then proceed to define with the client what their primary goals and budget are for the project. In your case, as it appears the aesthetic of a large concrete horn is paramount, I would then work with you in determining the SPL desired at the low frequency you desire, the level of distortion acceptable, physical environmentally dictated parameters, integration of the entire sound system as a synergetic entity providing your desired listening experience for each portion of the specific venue, and then do a cost analysis to determine if it is possible to complete all your goals within budget.
6A) The arrangement of drivers would be determined by the project goals.
6B) For sub-sections of the system, those different driver selections could possibly make sense.
6C) In the mid 1980's I designed a large straight horn system that was built by a former employee for a free concert provided by the Minneapolis based group "The Jets" on the island of Tonga. I now like to take advantage of travel opportunities myself whenever possible, so my design experience may take me to your property.
7) As is probably becoming clear to you, companies are marketing to old paradigms that many hold on to, while simultaneously producing drivers based on new paradigms that have surpassed the old.
Other than the demystification of "tapped horns", and the introduction of multiple driver virtual single point source horns, most everything I have applied in speaker cabinet building was explained quite well in the classic Sam's Publication "How to Build Speaker Enclosures" by Alex Badmaieff and Don Davis, my seventh printing copy is from 1970.
The "Handbook for Sound Engineers" edited by Glen Ballou, with many excellent authors of various chapters including Electroacoustic Devices is an indispensable source.
The most recent & comprehensive engineering texts on the subject of bass horn design exist here in the DIY sub forum, unfortunately the editing has not been completed ;^).
Cheers,
Art
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Eric,
I feel compelled to tell you that I have spent approximately 40 hours over the last month giving you free advice in your thread alone.
I have freely donated my knowledge and experience to hundreds of others since 1979. I have spent several man-years answering audio related questions on several forums.
In the last 40 years, I have only been paid for approximately the amount of hours I have spent attempting to help you. "Shame on me" for ever having received compensation from two members of this forum that decided to get some undiluted design work done by an expert, rather than "DIY".
In a fraction of the time I spent attempting to help you, had you simply consulted with me, you would already have finished blueprints detailing every aspect of a sound and lighting system design that would meet every one of your sonic and aesthetic goals.
Good afternoon to you, sir.
Art
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Ben,
There are a few forum members who's advice I agree with upwards of 95% of the time, but they also happen to post 95% less advice than I
.To achieve a 43% rating from an individual with almost completely different tastes in music and choices in audio reproduction actually makes me feel like I hit a home run each time at bat for at least one baseball season
.Thanks,
Art
I've discussed the high directivity of the large horns at length, this isn't some new revelation.
Pointing the beams at the same spot will aggravate the comb filtering situation.
Not pointing the beams at the same spot will lessen the power alley, make it less strong and accentuated.
Of course I still strongly favor the single mono sub concept as it eliminates most of the compromises.
I haven't ignored anything, I've posted a boatload of technical information to counter all of your inconsistent "recommendations".
Everyone here except you and Ben are pretty familiar with OP's goals and understand exactly what he wants to achieve. Some of that will maintain a bit of flexibility as he understandably wants to retain a bit of flexibility for experimentation. But most people here know exactly what he's trying to do.
I feel compelled to tell you that you spent 0.05 percent of 40 hours over the last month giving free advice. You spent 99.95 percent of 40 hours over the last month talking about yourself, picking fights and insulting people and namecalling.
This is about what I thought. You wanted OP to pay 20 billable hours for your advice and very likely a paid vacation to oversee the project (aka visit your girlfriend's daughter who you mentioned lives in the same area). I'm guessing you think your time is worth upwards of $100/hr, so roughly a bare minimum $2000 bill + expenses.
There's no shame in getting paid. But I draw the line when you INSIST or getting paid (dozens of times even after being told several times to stop it because this is a free diy website where free exchange of ideas is the only mission statement) or you won't provide clear answers and post inconsistent and bad recommendations.
There's no lighting involved here. And from the recommendations you've made it ate up roughly 15 minutes of your time.
Your exact recommendations were -
1. Dual subs with a very far center to center spacing.
2. Mains located beside or above the subs.
2b. Revised to mains above the subs at least 14 feet and maybe as much as 30 feet.
3. Toe in the subs to point at the center of the audience.
That's literally everything you have recommended in your "40 hours" of free advice. And somehow you think a picture of that (calling it a blueprint would be a bit over the top) is worth upwards of $2000 + expenses.
The worst part is the recommendations are very very bad and certainly won't have the characteristics like "locked in" performance through the crossover region that you claim are vitally important.
I'm not sure what the situation is but in all the years here I've never seen you mention money even once, now it's the only thing you want to talk about. This recent quoted post below seems to make it all a bit more clear, especially the underlined parts. I honestly hope everything is ok with you (honestly it doesn't seem like it's ok, that quote sounds very far from ok), I don't harbor any ill will and I wish you success in rebuilding your business as you seemingly come out of semi retirement. But I do not condone your actions in this discussion. There's simply no rebuttal to the techical details I've presented except for "your sims are not reality". But now it's Rog Morales sims too, and they fully agree with mine. Your recommendations here have been really inconsistent and really really bad.
http://www.diyaudio.com/forums/mult...-single-point-source-horn-57.html#post4890391
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"Where's the Beef"
After this level of collective effort I would expect to see at least a prototype design that meets requirements. Whatever those might be?
N.B. To be acoustically effective over the first decade, say 10-100 Hz. you will need a building permit form the county/municipality in which horn(s) are to be built.
If you are not in a rural area, other ordnances and covenants may prevent you from operating them once they are built.
Besides these limitations, what is the project budget limit, horn size limit and time limit?
Have you considered the commercial venue potential such a structure might provide?
That consideration could have a considerable impact on project scope and budget as well.
For fixed outdoor acoustical structures, moisture invasion into and sweating within the spaces housing the drivers should be a major concern.
The only acoustical issues for the sub-woofer horn is size, the shear stresses on the concrete walls and post install settling of foundation footers due to vibration.
Your horn construction choices here are:
a) a full horn on pylons, or
b) half a horn keyed to a monolithic slab.
Concrete placement of these is a non-trivial effort that will be subject to several inspections before the pour commences. Do not forget the conduit stubs for electrical service and signal cables that will be required.
Until you get past the issues raised here, the rest remains perfunctory details.
Regards,
WHG
After this level of collective effort I would expect to see at least a prototype design that meets requirements. Whatever those might be?
N.B. To be acoustically effective over the first decade, say 10-100 Hz. you will need a building permit form the county/municipality in which horn(s) are to be built.
If you are not in a rural area, other ordnances and covenants may prevent you from operating them once they are built.
Besides these limitations, what is the project budget limit, horn size limit and time limit?
Have you considered the commercial venue potential such a structure might provide?
That consideration could have a considerable impact on project scope and budget as well.
For fixed outdoor acoustical structures, moisture invasion into and sweating within the spaces housing the drivers should be a major concern.
The only acoustical issues for the sub-woofer horn is size, the shear stresses on the concrete walls and post install settling of foundation footers due to vibration.
Your horn construction choices here are:
a) a full horn on pylons, or
b) half a horn keyed to a monolithic slab.
Concrete placement of these is a non-trivial effort that will be subject to several inspections before the pour commences. Do not forget the conduit stubs for electrical service and signal cables that will be required.
Until you get past the issues raised here, the rest remains perfunctory details.
Regards,
WHG
Point for point OP has already mentioned almost 100 percent of those issues and how he plans to deal with them. It's a long thread but it's all back there somewhere ...
Regardless, as for myself, I really don't care if anything actually gets built or not (I'd probably wager 10 to 1 it won't happen), I'm here because I like discussing big horns. The "perfunctory details" are the only thing I really care about.
Of course it would be nice if it got built and we got lots of pics and measurements but I'm not holding my breath. I've been involved in lots of these really ambitious project discussions, the OP is always 100 percent certain they are going to build it and no one ever has yet. Maybe this OP will change everything ...
Regardless, as for myself, I really don't care if anything actually gets built or not (I'd probably wager 10 to 1 it won't happen), I'm here because I like discussing big horns. The "perfunctory details" are the only thing I really care about.
Of course it would be nice if it got built and we got lots of pics and measurements but I'm not holding my breath. I've been involved in lots of these really ambitious project discussions, the OP is always 100 percent certain they are going to build it and no one ever has yet. Maybe this OP will change everything ...
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If so ...
If so where is the design? And where is the criteria it is supposed to meet? What is see is a bunch of blind men fondling a different parts of the same elephant without knowing that its an elephant.
That type of effort is called "trivial pursuit" because it lacks a mission statement and a specific goal.
A project without a budget, time-line, site information/limitations, and mission statement are not worth the extensive effort exhibited here. WHG
If so where is the design? And where is the criteria it is supposed to meet? What is see is a bunch of blind men fondling a different parts of the same elephant without knowing that its an elephant.
That type of effort is called "trivial pursuit" because it lacks a mission statement and a specific goal.
A project without a budget, time-line, site information/limitations, and mission statement are not worth the extensive effort exhibited here. WHG
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Here's three reasons that this project will likely become a reality:
PC-128 excavator
HD-14 Dozer
Case 310 track loader
My labor costs are low, because I own the required construction equipment. The big unknown is the County permitting office. They are the only folks with the power to shut down my horn project before it starts. I'm anticipating that the county will ultimately issue my construction permit - with a very firm warning not to draw any sound nuisance complaints. . . .
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I’m going to build (qty 4) 1/4-space full size 15 Hz exponential horns – each with an 8 foot wide & 14 foot tall mouth. The left two horns will combine as a half-space stereo channel, and the right two horns for the right. Assuming most bass is recorded mono, I will essentially have a single full-space 15 Hz horn (with the ability to reproduce stereo, if needed – depending on my final crossover point. . .. )
If I cast my horns 10” thick on all sides, I’ll need roughly 17 yards of concrete per horn (not including the foundation abutments). Concrete is about 150 pounds per cubic foot, making my horns weigh 68,850 pounds each (just in concrete). Assuming I’ll use a moderate level of steel reinforcement, add 6 pounds per cubic foot for the rebar, or 2750 pounds per horn. All four horns combined will weigh about 286,420 pounds, or 143 tons (less the foundation abutment). This will cost about 8 grand in concrete (assuming around 110 bucks/yard), and 3.3 grand in rebar. The wall, and the horn foundation abutments will easily increase the amount of concrete & rebar by 50%. . . The big unknown is the forms. To be cost effective, I need to build just one set of forms, and use them four times. . . .
Some unresolved design issues are: mid-bass/mid-range horn design, and more importantly mid-bass/mid-range horn placement - i.e. place them to the sides of the bass horns, above the horns, or inside the horns. . . .
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It's rather fluid and flexible up to this point as theory, compromise and possibilities are discussed, as it should be. But OP has posted several iterations of design ideas and they have been discussed. If he had the required knowledge to do this he wouldn't have started the discussion, as it progresses and he learns more the design will become a working plan. Or just die out if everyone loses interest.
Have you not read the thread? He wants a large, straight concrete bass horn with built in flexibility to use anywhere from a single 12 inch driver to a bunch of 18s to drive the horn. The rest is all just details.
Clearly you either haven't been following from the beginning or simply are not paying attention then, because most people here know exactly what OP wants, OP is learning and the discussion is proceeding (albeit at a very slow and meandering pace due to some people that are just here to fight).
Whose effort are you referring to? OP's? If so I've addressed that.
Mine? This is the same as chatting over coffee for me, it's not really effort and it's already forced me to learn a new simulator and look for another new simulator to use. Win/win.
OP has given estimates of what he thinks this is going to cost a few times now. He's not dumb and clearly has worked with concrete before, we know this because he's shown pics of his concrete work.
Time line - not sure if it's been explicitly stated or not (can't remember) but I'm thinking next year. Who cares though? It won't start until it's designed and it won't finish until it's done (if ever), either way I couldn't care less about time line and I can't see it being of any interest to anyone except OP.
OP has provided copious details about the site, the amount and exact location of neighbors, the adjoining several hundred acres of government owned empty property, a site map showing the house, garage and two different proposed build locations, a desired audience area, he's talked several times about the amount and type of permits he needs, the types of container and/or buildings that his county will permit, how he is going to deal with neighbors, the small shack housing the wooden horn throat, sealed chamber(s), drivers and amps to shield these parts from the elements, how to get power out to the shack, as well as a few other things.
OP's mission statement is very clear. He wants to hear what a full size straight concrete exponential horn with extremely low distortion sounds like outside.
Did you somehow miss all of this? HOW!?! All of these things were covered, numerous times in some cases.
You make it sound like OP woke up one morning and decided he was going to build a massive structure in his back yard with no idea how to do it or how to deal with the bylaws and neighbors. And then a bunch of dummies started arguing about random aspects of something that could never become reality.
Despite OP's heavy machinery I still don't think it will happen but I'm a natural skeptic. The reason I gave him 1 in 10 odds instead of 1 in 1000 is not because of the heavy machinery he owns, not because he's worked with concrete and understands what it will cost and how to build it, not because of his massive playroom (shop) and clear desire to stay busy building things, not because he's had a very technical engineering career. It's because he seems willing and eager to learn. He's sometimes a bit slow to pick up certain concepts and they have to be repeated several times but for a rank amateur at this stuff he's picking it up quite well, he learned Hornresp, he's reading the technical papers, doing some of his own research, doing a fairly good job of ranking the importance and credibility of the massive amount of information that's being thrown at him here. 1 in 10 odds for a project of this magnitude as rated by a skeptic like me is VERY good - but it's still only 1 in 10.
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I still wish you would stop calling them that. Not that it matters, everyone knows what you are talking about at this point, but nothing about these horns is 1/4 space.
What you are thinking about building is a lot more like a single horn subdivided into 4 modular units and used in half space. Or if you want you could call it two horns subdivided into four modular units used in half space. Or you could even call it four horns used in half space.
But nowhere does 1/4 space enter the description of these horns. You are not designing them for use in 1/4 space and you are not going to use them in 1/4 space.
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