That's a pretty evasive answer to a pretty important question and we are just costing the sub horns not the whole system yet.
You need the price of "signal processors (digital crossovers, digital delays), wood for the forms, drivers". That might be as little as $6,000.
So, even without "costing twice what's expected" and leaving out the cost of earth-moving equipment and your time, your figures (concrete, forms, retaining wall....plus $6,000 for your identified items like DSP, wood, and drivers) are up to maybe $22,000.
Next, the cost of the speakers and other gear above the crossover, say $4,000.
Next the other craftspersons needed to help you, maybe $1,000 (a wild guess). And pizza for them and Port-A-Potty.
That's $27,000 without "etc" or adding 100% (or something) for contingency, as you joke.
Eric, please tell us you you are truthful in being prepared to spend $27,000 (or substitute your own limit) or tell us you are not.
Ben
I'm at about
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I'm not trying to evade your question. The simple answer is that I just don't know how much this project will ultimately cost. Several times I've posted that my horns (as currently planned) will cost 11 grand in just concrete and rebar. Include the retaining wall, horn foundation, the small outbuilding covering the horn throats, plus the wood for the forms - and the cost jumps to 17 grand. Then I'll need to purchase processors, drivers, and the dreaded "etc". In answering your question - yes, I am willing too cover the cost.
This is money well spent - for outdoor horns that will last 50-plus years in the elements. I know people who spent more on a grand piano for their house, and they don't even play it! At least I'll actually use my horns. . . .
One thing I hadn't thought of yet, is what if we ever decide to move? (We are not planning to ever move, but anything is possible). Would an outdoor horn system add or subtract, from the value of my property?
... yes, if it can be converted to fish pond.
Can we gather that you and your wife are prepared to proceed with the expectation you and your wife are prepared to spend $24,000 for this backyard feature, assuming it can be converted to a fish pond or at least be registered in the Guiness Book of World Records on your departure?
B.
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A fish pond draws raccoons, breeds mosquitoes, and presents a drowning hazard for small kids. I personally would pay extra for a house with bass horns.
Can you please provide your 2-cents on post 1039? This is a rather significant design aspect that remains unresolved? What would you recommend?
I think he means something like this? I must admit, a flat bottom with straight side-walls would be VERY easy to cast. However the top of the horn is going to be a serious pain. If I am to incorporate a flat surface (for ease of construction), ideally it would be the top of the horn - as the top of the horn is a reinforced slab in bending-tension, simply supported on ends (in other words, the top of the horn must be cast thick, and with lots of rebar). . . . I look forward to seeing his design proposal nonetheless. . . .
Why not build parabolic horns for ease of construction?
Hi Entropy455,
Post #1039: "see sketch"
I like the blue locations, and would keep them movable.
Post #1040: "Quote by David McBean: ... this means that the initial roof flare near the throat will be negative...", and "see sketch"
David is indicating that to maintain the proper area expansion w/ straight sides (top view) the top of the horn will initially slope downwards, not upwards as in your sketch.
Regards,
Post #1039: "see sketch"
I like the blue locations, and would keep them movable.
Post #1040: "Quote by David McBean: ... this means that the initial roof flare near the throat will be negative...", and "see sketch"
David is indicating that to maintain the proper area expansion w/ straight sides (top view) the top of the horn will initially slope downwards, not upwards as in your sketch.
Regards,
A Post Tensioned Hyperbolic Cylinder
for the roof. It does not need lots of rebar and will be even stronger. The horns are radially dispersed and share common walls between them. After several feet of travel, outside the horns this will be the wave front shape anyway. The mouth baffle should be cylindrical rather the flat. You could use CMUs for all the vertical walls. Use a center channel satellite as well. WHG
I think he means something like this? I must admit, a flat bottom with straight side-walls would be VERY easy to cast. However the top of the horn is going to be a serious pain. If I am to incorporate a flat surface (for ease of construction), ideally it would be the top of the horn - as the top of the horn is a reinforced slab in bending-tension, simply supported on ends (in other words, the top of the horn must be cast thick, and with lots of rebar). . . . I look forward to seeing his design proposal nonetheless. . . .
for the roof. It does not need lots of rebar and will be even stronger. The horns are radially dispersed and share common walls between them. After several feet of travel, outside the horns this will be the wave front shape anyway. The mouth baffle should be cylindrical rather the flat. You could use CMUs for all the vertical walls. Use a center channel satellite as well. WHG
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Will Do
The throat region will incorporate a precast monolithic circular to rectangular transition. Even though I am recommending a 80 Hz. c/o, I want to avoid beaming and cancellation issues in the throat at higher frequencies. Bill
Hi Bill,
Your proposed design should work very well indeed.
By using T = 0.6 and having in effect a "conical" expansion in the horizontal plane, I assume this means that the initial roof flare near the throat will be negative, to maintain the correct overall hyperbolic-exponential cross-sectional area expansion rate. Is this correct?
Many thanks. I look forward to seeing further details of your proposed design in due course.
Kind regards,
David
The throat region will incorporate a precast monolithic circular to rectangular transition. Even though I am recommending a 80 Hz. c/o, I want to avoid beaming and cancellation issues in the throat at higher frequencies. Bill
2-cents is more than my opinion is worth. I'm the person (only person?) with enough modesty not to bloviate about stuff he knows little about (and also the person who has lived with a corner horn for nearly five decades).
Any option for your backyard with any more than one horn (and with any sensible low end tailoff - say, 25-30 Hz - probably any more than one driver) is just plain nonsense. I wish you wouldn't persevere in having misunderstanding about lobes.
Matters very little where you put the mains. All the sound will seem to come from them. A highish crossover (120 Hz) will make for many benefits, not least is giving more scope to the great horn to play. If too much ping-pong effect, you can always mix the signals a bit. Wherever the mains are, you'll need to think-through the very important issues of time alignment. Weird all the nit-picking about phasing and lobes and barely a thought about how to handle gross time alignment. Use "string theory" to contemplate the timing.
Just my opinion, but I'm skeptical about anybody who says they are proceeding with a backyard gimmick that costs $25,000, not the least, I'll say again, in Seattle. Work on a system design that is feasible. I'd certainly aim my system for great music on a patio where I read the daily newspaper rather than having fantasies about occasional hot-tub orgies to music*.
You did ask for my opinion, eh.
Ben
*OK, maybe I was just wondering what a poor sim advocate day-dreams about at night reading his sim plots all alone in his folks' basement
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Exactly this. You asked (in post 149) and were advised to use a flat bottom, but until now, none of your sketches reflected this.
I think what you have drawn in 1040 (or similar) would be the way to go.
Rather than have the walls conical all the way, I'd make the walls expo for the first metre or two, and then conical for the mouth, so that the initial roof flare near the throat will not be negative. To me, that goose-necking seems bad (but maybe my intuition is wrong, and it has no actual penalty).
A side benefit of a flat base (or near-flat; I'd use a very slight incline for drainage) would be that you could easily roll the main boxes in and out on something like a garage creeper: position them in front of the horns for listening sessions, and roll them into the horns the rest of the time.
How deep are you planning to bury these? I'm curious why you've decided on 10" thickness.
I don't recall that you have a schedule, but I do think that some experimentation should be a priority before you get too committed / spendy. You seem to have roughly quadrupled the original budget estimate, without having done any tests.
e.g. the 30Hz horn linked below was a 2-day build. Making something quick & dirty of ~this size and listening to it would surely suit someone who says:
e.g. it might refine:
- ideas about how much directionality you'll get (and thus how loud you can crank it without bothering neighbours)
- decisions about how to do angles / joins / formwork
- level of SPL desired / power / driver numbers
I think that getting some personal practical knowledge of this would be worth a 2-day build. If the weather is poor, you could make the prototype in the comfort of your big shed (firing out the doorway, naturally), then dismantle it after trials, to re-use the ply for formwork. That is: it would cost almost nothing to try it.
http://www.diyaudio.com/forums/multi-way/298525-artichoke-horn.html
Note that when I sim a bad version of the linked horn (a crude conical approximation of the flare, halving the box size and doubling throat area), the sims stay within 2dB of the 'ideal' version. This is much less than the normal in-room bass variation you get from standing up or changing seats. ....thus even a quick & dirty build should give you a fair taste of what a bigger, better version could deliver.
As shown in the attachment.
Bill proposes a throat adaptor transition in this region, so it should not be an issue in practice.
Attachments
I busted out the graphing calculator, and sure enough - there's some concavity in the roof of the horn near the throat, when using a flat bottom (ground-plane) joined with two tapered flat-straight walls.
Question - what am I sacrificing if I do this?
Perhaps a better question - would the 1000 Hz radian horns on my wife's stereo sound just as good, if the horns had a flat-bottom plane, with two tapered flat side-planes, with an exponential-curvature top? My gut tells me the horns would not sound as good as all four horn walls undergoing exponential expansion.
Wouldn't you get a more uniform impedance matching throughout the horn, when the wave-front in the horn is undergoing a more "uniform" expansion process? Or said another way - the dominant wave expansion will be along the top wall of the horn - with minimal wave expansion along the horn's bottom wall. This will shift the horn's center-axis into the air, and not necessarily parallel to the ground. This feels like a design compromise. . . .
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Originally Posted by whgeiger
The sizes you are contemplating represent marked acoustic overkill.
Wow, you have been busy asking questions while we were celebrating Thanksgiving with old friends from several states who gathered near Tampa, a couple hours drive from us.
Answers to all your questions, in chronological sequence to when they were all asked:
1) I won't speak for whgeiger, but I as I have already told you, I have heard outdoor bass horn systems with flat response to 25 Hz, less than one octave above your proposed horns. There would have been absolutely no reason for any of those systems to be built with 15 Hz response, as none of the program material presented had any musically relevant reasons to roughly double the size of the system to provide lower fundamental notes that can be "heard" through their harmonics above 25-35 Hz.
2) Yes, though a much smaller horn with a 25-35 Hz low corner can be made with as much efficiency as a much larger horn with a 15 Hz low corner.
3) I have not seen anything "ideal" about your non-existent horn(s), they seem more like an idle man's idol to a self- admitted lack of acoustical knowledge than anything else.
4. Are you "listing" to port, or starboard?
The person next to me is well over 1000 miles from you, what difference could the dynamic range of your your proposed horn(s) possibly have on us?
What do you consider a a reasonable amount of dynamic headroom over a conversational level of 65 dB SPL, would you consider "twice as loud" +10 dB SPL adequate, or perhaps four times (+20 dB) as loud, a whopping 85 dB, or front row at the RHCP 130+ dB reasonable? Hint - no one in the front row at a rock concert is going to understand a 65 dB SPL conversation unless they are a lip-reader.
5. Which lesson are you writing about, you have failed to incorporate any advice in "your" horn design other than that provided by a troll who appears to have abandoned your thread after you ignored most of what he had to say, too.
6. A life jacket, compass and course plan ;^) .
7. Your awareness is not mine.
I can easily hear 7.5 Hz (an octave below 15 Hz) at a level of under 80 dB, a level the Sony MDR-7506 headphones have no problem reproducing with no audible distortion.
This level does not make me feel sick to my stomach, but as little as 100 dB SPL at 15 Hz starts making me feel a similar form of nausea as I feel when "seasick" or "carsick".
Eric, your long term exposure to fairly high levels of VLF on a submarine may render you immune to the "seasick" sensation I experience.
8. Side by side placement of any audio source maximizes, not minimizes comb filtering in any position other than "dead ahead". Off axis (off-course) comb filtering ranges from minimal, to "bad" to "worse" dependent on wavelength and spacing.
Had you been paying attention to what Just A Guy, or any other guys providing content in your thread have written, you would have understood why you statement is utterly false.
9. Big flaw is your clinging to "your" horn plan, which you came up with prior to learning the audio concepts needed for system design.
10. You have not issued timelines for design or construction proposals, so it would be impossible for you to be "behind schedule".
11. Simulations, sketches proposals, questions and answers are all in abundance in your thread, but you have thus far not presented a bass horn "system" design.
12. Post # 1027 gives you an idea of what audio design criteria "look like".
I have absolutely no idea as to what you "should ultimately think that matters" other than your preferred building materials and possible system components.
Preferred building materials and possible system components have very little to do with audio system design.
13. If a dysfunctional "system" were to be built as in the sketch in post 1067, it would definitely create lobing "issues" through the region of overlap of the bass horn's to low mid crossover frequency, as well as the upper range of the bass horns.
What do you mean by "I'll have better far-field stereo separation" ?
14. Are the elevated positions out in front of the horns a monument to the dear departed Purple One, or some other "design element" related to audio?
15. Both myself and many others have given you literally days of written "Constructive feedback . . . " which you have chosen to ignore, as you also continue to answer any of the questions that would give us information needed to help you towards your thus undefined audio goals.
I'll leave the construction details to you.
16. "Your" horn could be built with straight top, side and bottom sections, and still conform exactly to the cross sectional area of any simulation that you choose to use as a "template".
17.A) I had, and gave my opinion several hundred posts ago.
B) Based on sale of my New Mexico property with a well-integrated purpose-designed sound system that seamlessly interlinked the home theater, kitchen/dining room, work shop, and back outdoor/deck/hot tub locations, was that the buyer did not pay a penny more at closing than he would have if the property had no sound system.
My opinion as an experienced audio design consultant and purchaser of property for both homestead and income use, is that an improperly designed concrete edifice would subtract from an offer exactly the cost of removing the edifice and returning the landscape to it's natural state.
18) If you reconsider my answer #16, you may want to "bust a move" on your calculator again ;^).
19) You are sacrificing a lot of time and effort to build something that could be purchased as a turn-key system, or rented for each planned event for a fraction of the cost of the materials alone. What you may learn, if you start reading, would be priceless.
20) Without having the model number of your wife's horns, no way to comment on your question- we don't even know what your wife's horns look like, much less their polar response.
21) I would trust polar charts of your wife's horns a lot more than your "gut".
22)"More uniform impedance matching" than what?
23) For there to be a "design compromise", there must be an actual design, see 11 above. Again, reconsider my answer #16, which is a repeat of answers you ignored hundreds of posts back.
Eric, you may know "all there is to know" about mixing and pouring concrete.
To learn how to design an audio system the first step is to come up with your own specific set of audio goals.
Perhaps consider what I presented you in my last post, the audio design criteria for the SynTripP, other than a few age and weight related issues, may be almost exactly what you want, or not- only you can decide for yourself.
I won't bother attempting to give you any more advice until you answer the questions I have asked in this and other threads in an attempt to figure out exactly what you want in terms of audio design goals.
Cheers,
Art
The sizes you are contemplating represent marked acoustic overkill.
Eric,
Wow, you have been busy asking questions while we were celebrating Thanksgiving with old friends from several states who gathered near Tampa, a couple hours drive from us.
Answers to all your questions, in chronological sequence to when they were all asked:
1) I won't speak for whgeiger, but I as I have already told you, I have heard outdoor bass horn systems with flat response to 25 Hz, less than one octave above your proposed horns. There would have been absolutely no reason for any of those systems to be built with 15 Hz response, as none of the program material presented had any musically relevant reasons to roughly double the size of the system to provide lower fundamental notes that can be "heard" through their harmonics above 25-35 Hz.
2) Yes, though a much smaller horn with a 25-35 Hz low corner can be made with as much efficiency as a much larger horn with a 15 Hz low corner.
3) I have not seen anything "ideal" about your non-existent horn(s), they seem more like an idle man's idol to a self- admitted lack of acoustical knowledge than anything else.
4. Are you "listing" to port, or starboard?
The person next to me is well over 1000 miles from you, what difference could the dynamic range of your your proposed horn(s) possibly have on us?
What do you consider a a reasonable amount of dynamic headroom over a conversational level of 65 dB SPL, would you consider "twice as loud" +10 dB SPL adequate, or perhaps four times (+20 dB) as loud, a whopping 85 dB, or front row at the RHCP 130+ dB reasonable? Hint - no one in the front row at a rock concert is going to understand a 65 dB SPL conversation unless they are a lip-reader.
5. Which lesson are you writing about, you have failed to incorporate any advice in "your" horn design other than that provided by a troll who appears to have abandoned your thread after you ignored most of what he had to say, too.
6. A life jacket, compass and course plan ;^) .
7. Your awareness is not mine.
I can easily hear 7.5 Hz (an octave below 15 Hz) at a level of under 80 dB, a level the Sony MDR-7506 headphones have no problem reproducing with no audible distortion.
This level does not make me feel sick to my stomach, but as little as 100 dB SPL at 15 Hz starts making me feel a similar form of nausea as I feel when "seasick" or "carsick".
Eric, your long term exposure to fairly high levels of VLF on a submarine may render you immune to the "seasick" sensation I experience.
8. Side by side placement of any audio source maximizes, not minimizes comb filtering in any position other than "dead ahead". Off axis (off-course) comb filtering ranges from minimal, to "bad" to "worse" dependent on wavelength and spacing.
Had you been paying attention to what Just A Guy, or any other guys providing content in your thread have written, you would have understood why you statement is utterly false.
9. Big flaw is your clinging to "your" horn plan, which you came up with prior to learning the audio concepts needed for system design.
10. You have not issued timelines for design or construction proposals, so it would be impossible for you to be "behind schedule".
11. Simulations, sketches proposals, questions and answers are all in abundance in your thread, but you have thus far not presented a bass horn "system" design.
12. Post # 1027 gives you an idea of what audio design criteria "look like".
I have absolutely no idea as to what you "should ultimately think that matters" other than your preferred building materials and possible system components.
Preferred building materials and possible system components have very little to do with audio system design.
13. If a dysfunctional "system" were to be built as in the sketch in post 1067, it would definitely create lobing "issues" through the region of overlap of the bass horn's to low mid crossover frequency, as well as the upper range of the bass horns.
What do you mean by "I'll have better far-field stereo separation" ?
14. Are the elevated positions out in front of the horns a monument to the dear departed Purple One, or some other "design element" related to audio?
15. Both myself and many others have given you literally days of written "Constructive feedback . . . " which you have chosen to ignore, as you also continue to answer any of the questions that would give us information needed to help you towards your thus undefined audio goals.
I'll leave the construction details to you.
16. "Your" horn could be built with straight top, side and bottom sections, and still conform exactly to the cross sectional area of any simulation that you choose to use as a "template".
17.A) I had, and gave my opinion several hundred posts ago.
B) Based on sale of my New Mexico property with a well-integrated purpose-designed sound system that seamlessly interlinked the home theater, kitchen/dining room, work shop, and back outdoor/deck/hot tub locations, was that the buyer did not pay a penny more at closing than he would have if the property had no sound system.
My opinion as an experienced audio design consultant and purchaser of property for both homestead and income use, is that an improperly designed concrete edifice would subtract from an offer exactly the cost of removing the edifice and returning the landscape to it's natural state.
18) If you reconsider my answer #16, you may want to "bust a move" on your calculator again ;^).
19) You are sacrificing a lot of time and effort to build something that could be purchased as a turn-key system, or rented for each planned event for a fraction of the cost of the materials alone. What you may learn, if you start reading, would be priceless.
20) Without having the model number of your wife's horns, no way to comment on your question- we don't even know what your wife's horns look like, much less their polar response.
21) I would trust polar charts of your wife's horns a lot more than your "gut".
22)"More uniform impedance matching" than what?
23) For there to be a "design compromise", there must be an actual design, see 11 above. Again, reconsider my answer #16, which is a repeat of answers you ignored hundreds of posts back.
Eric, you may know "all there is to know" about mixing and pouring concrete.
To learn how to design an audio system the first step is to come up with your own specific set of audio goals.
Perhaps consider what I presented you in my last post, the audio design criteria for the SynTripP, other than a few age and weight related issues, may be almost exactly what you want, or not- only you can decide for yourself.
I won't bother attempting to give you any more advice until you answer the questions I have asked in this and other threads in an attempt to figure out exactly what you want in terms of audio design goals.
Cheers,
Art
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A system this large 'begs' to be an outdoor cinema where LFE can require significant <10 Hz output:
The Low Frequency Content Thread (films, games, music, etc) - Bass Content - Data-Bass Forums
The New Master List of BASS in Movies with Frequency Charts - AVS Forum | Home Theater Discussions And Reviews
GM
Nothing AFAIK if done correctly as this RCA horn [AKA the 'Ubangi'] was done and referenced earlier by Art:
single driver: https://www.google.com/search?q=RCA...ved=0ahUKEwjKlt7jocXQAhWGJiYKHZD2CZEQ_AUIBigB
dual driver: https://www.google.com/search?q=RCA...xCYKHVLSCpIQ_AUICygE&biw=1242&bih=580#imgrc=_
GM
http://www.voidaudio.pl/attachments/article/147/A Practical Guide To Bass Arrays (angielski).pdf
(1) Page 5 & Page 6 of the above link clearly show that your recommendation to toe in my horns, was in fact a bad recommendation.
(2) Comparing page 16 with page 8 of the above link, clearly shows that side-by-side placement of LF audio sources will minimize comb filtering, and not maximize it. I can only assume (seeing as you claim to be a sound-reinforcement professional) that you’re intentionally trying to mislead me - again – simply because I refuse to pay you a consultant fee - for your input on a DIY audio website. . . .
I ask about horn placement, and you ask me the color of my mustang??? (If you'd been paying attention to post #765, you’d already know. . . .) A more relevant question would be to ask whether or not I’m going to add a coloring agent to the concrete mix. A really dark brick-red would be cool for the horns, with an a greyish-black for the retaining wall. . .
Seriously weltersys - either contribute to this thread in a constructive fashion, or please go away. . . .
The biggest potential issue I see with building the below horn (with the top wall actually having a slightly concave shape as shown above), is that I'll have two approximately parallel horn walls from X=50 to X=200. One thing practically every horn design reference has in common, is that parallel surfaces inside a horn are bad. . . .
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