You can save as many designs as you like, and compare any of them to each other in Hornresp.
As JaG has already suggested (many times 🙄), that includes comparing them to bass reflex designs as a "reality check", there is no advantage to a TH if it is less efficient regarding output compared to size and materials, and a TH requires the top cabinets to be delayed to properly time align.
Your bizarre spreadsheet does not allow comparison to any known metric, so you won't know when you have perfected sin, or whatever else you want to.
But as long as you are having fun chewing through the restraints, it's a wonderful world, as Devo used to say "for you, for you, not me".
RIP, Bob Casales.
Look at figure ten in the Danley Patent Application. Then look at my bizarre spreadshet "F1+F3" chart. Keep in mind that Danley's is probably from a well-designed horn (two or more) in his graph. Mine is the combined outputs of a modeled cylindrical quarter wave TL. I like Devo too: "I've got a surge an urge and it's out of control..."
But yes, with my luck, a bass reflex will sim better 🙂
But yes, with my luck, a bass reflex will sim better 🙂
Progress! I've gnawed off the left cuff, but I can't reach the scalpel on the table. So now working on the right. 
On a more serious note, look at the two graphs attached. These are combined response from a 1/4 wave and a 3/4 wave (3x longer) cylinder TL. Note how messy both are. And now consider that these summed to the (in my opinion) cleaner curve "F1+F3" in my bizarre spreadsheet.
"At last, it has all become clear to me! I am the captain of the cheese, and you are the lemon merchant." -- Ren and Stimpy "Space Madness"
On a more serious note, look at the two graphs attached. These are combined response from a 1/4 wave and a 3/4 wave (3x longer) cylinder TL. Note how messy both are. And now consider that these summed to the (in my opinion) cleaner curve "F1+F3" in my bizarre spreadsheet.
"At last, it has all become clear to me! I am the captain of the cheese, and you are the lemon merchant." -- Ren and Stimpy "Space Madness"
I have no idea what you are trying to do here, maybe you could explain it in detail.
Regardless, you can't sum frequency response graphs alone, you need phase info as well. Are you taking phase into account?
Regardless, you can't sum frequency response graphs alone, you need phase info as well. Are you taking phase into account?
They are messy because that's what undamped constant csa transmission lines look like. As I mentioned, you could add a bit of taper to the line and a bit of stuffing and have almost ruler flat response with either example. Make the driver and mouth physically near each other and there won't be any massive shifts in response as you move around the sub. I've got some experience with MJK's worksheets (which could simulate stuffing before Hornresp was able to) and it's extremely easy to get flat response from transmission lines, no need to do whatever it is you are attempting to do here.
Perhaps you could state a goal and ask for advice instead of trying to reinvent the wheel without understanding the physics behind it.
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You have identified my problem: I have too many goals (or perhaps a lack of a specific one). I don't want to re-invent the wheel, but I do want to understand, at least superficially, how it works. I do want ot understand the science behind it.
In your post (#45) you touch on both problems and solutions: I do like the Sonotube ("constant csa" -- I admit I dunno what "csa" is yet) transmission line. They are easy to make, needing almost no construction whatsoever. As you note they have various problems, such as the phase/freq. vs. position problem and potential solutions (taper, stuffing). However, one solution (stuffing) also reduces the efficiency.
For right now, let us say my goal is just to model (and therefore gain an understanding) of Danley's tapped horn model. In my sims submitted above, I thought I might have found a key.
My question: could Danley's method be as simple as to take two or more backwaves, delay them by different amounts, and recombine these with the forward wave of a driver?
My "experiment" (to sim): Hypothesis: use two identical drivers. Each one will model as a basic transmission line with length of quarter-wave and 3x the quarter-wave respectively. No taper or stuffing for now. Sum all four of these outputs and see what the result is.
Result: looked promising, seemed quite smooth (but not flat) perhaps to 150 Hz. Problems: I did not account for phase.
Next experiment: Do I need to account for phase? Do I need a better model, one that can simulate multiple paths, multiple drivers? I don't think Hornresp can do this (at least I don't know how).
Inventing a new wheel, perhaps: I am broading the area of experimentation into areas that perhaps are new, at least that I have not seen experimented with her at DIYaudio: building a subwoofer of any design, with two or more drivers, each driver having a different tuning. The closest I have seen is some variations of the spiral horn that use multiple horn lengths. However, those are single driver designs.
In your post (#45) you touch on both problems and solutions: I do like the Sonotube ("constant csa" -- I admit I dunno what "csa" is yet) transmission line. They are easy to make, needing almost no construction whatsoever. As you note they have various problems, such as the phase/freq. vs. position problem and potential solutions (taper, stuffing). However, one solution (stuffing) also reduces the efficiency.
For right now, let us say my goal is just to model (and therefore gain an understanding) of Danley's tapped horn model. In my sims submitted above, I thought I might have found a key.
My question: could Danley's method be as simple as to take two or more backwaves, delay them by different amounts, and recombine these with the forward wave of a driver?
My "experiment" (to sim): Hypothesis: use two identical drivers. Each one will model as a basic transmission line with length of quarter-wave and 3x the quarter-wave respectively. No taper or stuffing for now. Sum all four of these outputs and see what the result is.
Result: looked promising, seemed quite smooth (but not flat) perhaps to 150 Hz. Problems: I did not account for phase.
Next experiment: Do I need to account for phase? Do I need a better model, one that can simulate multiple paths, multiple drivers? I don't think Hornresp can do this (at least I don't know how).
Inventing a new wheel, perhaps: I am broading the area of experimentation into areas that perhaps are new, at least that I have not seen experimented with her at DIYaudio: building a subwoofer of any design, with two or more drivers, each driver having a different tuning. The closest I have seen is some variations of the spiral horn that use multiple horn lengths. However, those are single driver designs.
Refining the current "goal": since I am trying to simulate, here is a question of the phase: I begin with Danley's model. I change single driver to two separate drivers. Call them A1, A2. Both of them are driven in phase so they should sum perfectly. Each will have a separate backwave, call them B1, B2. These will be different because of the different horn (TL) lengths.
One thing (perhaps more!) my prior sim did not account for is the possible interactions of all four of these. I see no reason I would need to account for phase but just because I don't see something doesn't mean it doesn't exist 🙂
One thing (perhaps more!) my prior sim did not account for is the possible interactions of all four of these. I see no reason I would need to account for phase but just because I don't see something doesn't mean it doesn't exist 🙂
Hi Soldermizer,
You need AkAbak to model what you are describing. For a starting point, here is a script that has two drivers, and models the horn as a series of ducts. http://www.diyaudio.com/forums/subwoofers/134369-dual-8-tapped-horn-th-spud-7.html Post #61. I consider geitmans thread a must read (study through) for people building tapped horns.
Regards,
You need AkAbak to model what you are describing. For a starting point, here is a script that has two drivers, and models the horn as a series of ducts. http://www.diyaudio.com/forums/subwoofers/134369-dual-8-tapped-horn-th-spud-7.html Post #61. I consider geitmans thread a must read (study through) for people building tapped horns.
Regards,
Yes, phase response is what makes it possible to make one driver appear as two in a tapped horn, or why a bass reflex (phase inversion) enclosure works.
Hornresp can simulate TH using single or multiple drivers and will show the phase response.
It agrees quite closely with measured results (if the build reflects the simulation).
You do need to read the instructions to get much out of the program.
There is a "Hornresp for Dummies" thread, but not sure if it is also appropriate for ijits.
Might be worth a try..
One applies voltage to a pair of speakers either wired in the same polarity or with one reversed polarity.
The enclosure's output phase at any given frequency is dependent on the cabinet design, and speaker parameters.
I appreciate your enthusiasm. Very much. You remind me a lot of myself when I was starting out. When I started I didn't know anything about anything about construction or audio theory. I learned how to use the very limited power tools I had at hand, managed not to cut any fingers off, used a huge amount of construction adhesive to fill in gaping holes from wobbly cuts, found a few cheap, crappy drivers and scrap wood and built a few subs from plans on the internet but they didn't live up to the hype. One day about 8 years ago I built something and it had chuffing problems. I had no idea what was happening, what was causing it, or what to do about it but I hated it. All that work down the drain and I didn't even know why. That's when I started learning. Reading good resources takes a lot of time. It's invaluable but it's slow. Playing with a simulator can teach you a lot more a lot faster. It takes awhile but a little experience goes a long way, both with construction skills and knowledge of theory. Your base will grow exponentially if you slow down and concentrate on the basics.
The most common advice I got when I was starting out was "just build something, you won't learn if you don't experience". A common phrase in the same vein is "paralysis by analysis". This is true to a certain extent, you do need to build SOMETHING, but at some point you have to stop and learn. A few years ago I stopped building almost completely and finally now I know almost enough to start again with the expectation that anything I decide to build will do exactly what I expect it to.
Believe me, I had the same thoughts as you. Why not build a box with lots of differently tuned ports? Why not build a bunch of ported boxes, each box tuned to a different note? Thankfully I never tried because it doesn't work, at least not without extensive engineering and a good idea of how to make it work.
With a tapped horn the throat side tap is doing all the work, the mouth side tap is just filling in a naturally occurring hole in response, but at the same time it brings a lot of garbage at other frequencies and phasing issues into the picture, without simulation a successful tapped horn is almost impossible. Technically it is possible to do what you want, but you can't do it they way you are attempting to, and it doesn't make sense to try. You will find this out if you study the separate contributions of the throat and mouth side tap in a tapped horn.
csa = cross sectional area
Stuffing does reduce output, that's what it's there for. But it's not nearly as bad as you think if you apply it right. Stuffing in the first half of the line will attack the higher resonances and mostly leave the low frequency response intact. But as soon as you start putting the stuffing in the last half of the line, and especially near or in the terminus or port, it will completely kill off the low frequency content.
As I mentioned, it's easy to get almost ruler flat response with a bit of taper and stuffing, and it doesn't have to cost a lot in low frequency efficiency.
This isn't new, I certainly thought of this when I was starting out and I would imagine most people do. But it doesn't work the way you think it does because of phase. I'm not talking about polarity (as weltersys pointed out), I'm talking about the phase graph in Hornresp. You can't sum frequency response without phase info.
Hornresp can't do what you want but Akabak can (as tb46 mentioned). Akabak is wonderful but cryptic and very hard to learn. There is a much easier program that will do everything you require here - http://www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software.html
This program is easier to use than Hornresp, it's even easier than WinISD once you understand how to manipulate it.
So here's a quick sim to show you how combined responses work.
First graph - an end loaded tl with 100 in2 csa, 115 in length, note the hole at 110 hz (this notch is what tapped horns were designed to fill in by the way)
Second graph - same driver in an end loaded tl, 100 in2 csa, 28 inch length, length determined by the resonance at 110 hz to fill in the hole in first graph tl
Third graph - combined response of both lines fitted to the same driver
Fourth pic - the enclosure schematic of the dual line tl
An externally hosted image should be here but it was not working when we last tested it.
As you can see, you can't just sum frequency responses. Phase has a huge effect, and some frequencies will add and some will subtract based on response and phase together. The hole at 110 hz is somewhat filled in, but there are now a host of other problems.
The tapped horn works on this principal but on an advanced level, in a way that's actually proven to work.
The tapped horn isn't the only way to fill in naturally occurring holes in response, a normal tapered and stuffed tl is the traditional way, and the regular tl will be almost as loud (very close) to the tapped horn, and have several benefits over the tapped horn - more bandwidth, flatter response, less phase problems, etc. But what you are trying to do is recreate the way tapped horns work with a method that won't work.
Anyway, I'm cutting back on posting publicly, at least for awhile. Unless a major problem or a challenge to the information I've posted pops up, I'm done with this thread. Weltersys and tb46 are both very smart and have decades of experience between them, it would be in your best interests to listen to anything they say. And I'll be available by email if you want.
Good luck.
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Correction - this program won't sum two separate different systems (so it won't do everything you require) but it will show you why you shouldn't bother trying, at least not until you understand the frequency response and phase relationship. Akabak will do it. If you don't want to learn Akabak you need excel or similar program to sum phase and frequency response, not just frequency response alone.
(I knew what I meant, I just didn't say it right.)
To Guy (mostly) and the others too: thank you for all the responses. I do have a lot to learn. I will continue with my simulations, even they can be a challenge. As for the Ijit I, I am caling it a failure (to no surprise, seeing how it was built with little planning.) A future cabinet will have a better attempt at bracing. I just could nto get rid of the rattles. For the time beimng, I have gone back to the long tube. It may not be perfect but no rattles, and didn't even need to caulk (yet).
Just a guy, third response graph shows a speaker response curve (not port as in your example) I intentionally slapped together about a year ago. Once in room that null at 120 was countered by the room peak and nulled it out quite nicely.
I was stunned and had to figure out why some POS mockup sounded so well 😉
I was stunned and had to figure out why some POS mockup sounded so well 😉
Yeah, design a too small bass horn that has its 'ripple' ~ line up with the appropriate room modes and it's amazing how much bass output one can obtain in a small net bulk.
GM
GM
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Help the Ijit..simulate and plan his 2nd (working) TH.
First, here is the photo of the mailing tube that I briefly considered making a transmission line from. (Some of you guys are even sicker than me! Go ahead...I expect replies on this thread like: "well you can put two Dayton 5" subs in each and you should get a low corner of 50 Hz..." Don't disappoint me.)
Secondly, the "gotta build something!" feven has broken -- temporarily. During this period of sanity, perhaps brief, I would like to do the following:
1. Read and plan about tapped horns. Simulate known "good" designs, as well as make my own abominations.
2. Plan to build a real one, either of my own design or more likely a good one.
Right now, hornresp is my only sim tool. Does anyone know of a collection of "good" designs in hornresp format? While it's not difficult, it is some work to have to type in all the numbers from the screen shots.
Also, I am trying to apply myself just a littlle more to my studies. The semester is half over and important deadlines are coming up real soon, just like a spoonful of Ipecac syrup 🙂
First, here is the photo of the mailing tube that I briefly considered making a transmission line from. (Some of you guys are even sicker than me! Go ahead...I expect replies on this thread like: "well you can put two Dayton 5" subs in each and you should get a low corner of 50 Hz..." Don't disappoint me.)
Secondly, the "gotta build something!" feven has broken -- temporarily. During this period of sanity, perhaps brief, I would like to do the following:
1. Read and plan about tapped horns. Simulate known "good" designs, as well as make my own abominations.
2. Plan to build a real one, either of my own design or more likely a good one.
Right now, hornresp is my only sim tool. Does anyone know of a collection of "good" designs in hornresp format? While it's not difficult, it is some work to have to type in all the numbers from the screen shots.
Also, I am trying to apply myself just a littlle more to my studies. The semester is half over and important deadlines are coming up real soon, just like a spoonful of Ipecac syrup 🙂
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You got that right! I'm still repairing all the damage I did to mine back in 2k with a 'stereo' pair of corner loaded SD Contrass kits/500 W during a 120+dB SPL low B pipe organ symphony recital. 🙁 I learned the hard way that cheap 'stick' built framing with 'floating' floor construction can have a relatively high Fs.
GM
GM
I have started posting on a competitior site to lessen the mental drain on you guys 🙂
I visited Lowe's last night, to scout materials. I was amazed to find the cheapest "wood" in 4x8' (or 5'x5') is called OSF something-or-other and well under $10/sheet. I kind of like the "random" wood splinter finish and wonder if it would finish well. I am aiming for minimal cutting if possible. I'd like to build between two 4x8 sheets (thick/high probably 2' or 3' with an 18" woofer). I also found a product called "cement board" that I'd not seen before. It looks like it would be good for dividers but not load bearing walls, such as for a 50 LB subwoofer driver 🙂
I visited Lowe's last night, to scout materials. I was amazed to find the cheapest "wood" in 4x8' (or 5'x5') is called OSF something-or-other and well under $10/sheet. I kind of like the "random" wood splinter finish and wonder if it would finish well. I am aiming for minimal cutting if possible. I'd like to build between two 4x8 sheets (thick/high probably 2' or 3' with an 18" woofer). I also found a product called "cement board" that I'd not seen before. It looks like it would be good for dividers but not load bearing walls, such as for a 50 LB subwoofer driver 🙂
OSB (Oriented Strand Board) is horrible for any but the smallest of speaker boxes.
Do your best to stay away from it.
Some call it chip board as it is literally big chips of wood glued, pressed and used for cheap under layment in house trailers, or patching broken greenhouse windows (it works great there)😀
"Cement Board" or backer board works good for making showers from tile and tiling above your bathtub. It is a Tile backer board and tile is glued to it.
I think in a sub it would slowly crumble, but it does have allot of mass.
Dave
PS,
GM every time I think of the story you told of your house falling down around you and it raining 50 year old drywall and rockwool on your heads, well I just have to smile. But I'm smiling with you, not at you. Or..I mean I'm smiling at you, not..Umm.oh you know what I mean. I can't imagine being there when that happened.
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