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Old 21st January 2009, 02:54 PM   #211
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one extremely similar to that one, i dont know if its 100% right though, i doubt it is, started with a 545 litre box, chose my width, and made it 105x105cm, so about 550l, then proceeded to try and place panels inside so that the surface area/distance remained as constant as possable. pretty much just fancy trial and error.

i havent been able to find a site with a step by step of someone folding their horn, but im sure theres some tips and tricks im missing.

im starting to greater understand the parameters now! s1-s2 is distance from the throat to the centre line of the driver, and 23-24 is centreline-mouth(is this corret?), and then s2-s3 is the big distance i need to"fold" to fit my size and shape of box yes?

i was previously under the impression that these controlled horn segment sizes, as opposed to that AND driver positioning.

once again, really sorry for the onslaught of questions and impossable simulations!
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Old 21st January 2009, 05:05 PM   #212
FlipC is offline FlipC  United States
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xstephanx

I simplify things by doing the throat and mouth to correct proportion and then just make sure the folds are expanding. I don't sweat that they are 100% exact. Also if you notice in jbell's diagram, corner wedges are missing. After lots of reading it just isn't needed. Though I would block brace those joints.

Also look up the Apache MK 1 and MK2.
Which JBells is close to.
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Old 21st January 2009, 06:27 PM   #213
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reagrding expansion rate: ok! that makes things alot easier!

i realised that s1-s2 can be a little shorter(down to 20cm for a 15" driver) as can s3-s4, so ive made them as short as possable (as this gives best response)

to get the line length i want in the volume i want, my best bet is to make one like j bells, however eliminating the first little expanding section so its just a big spiral.

maybe i can have this drawn up by tonight and built by tomorrow.

my deadline for this project(yes theres a deadline) is feb 14th, i plan to throw a little shindig in my living room(10x25'), and if the sims are correct its gonna be a pretty loud little shindig


also, if i use an edgeways 2x4 to brace the mouth(its going to be 90cm high, 50cm wide), will i need to factor that into my mouth area calculations? i get this feeling that it wont make much of an impact causeof the wavelengths this thing will be dealing with, but i could be wrong.
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Old 21st January 2009, 07:23 PM   #214
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Both Tom Danley and John Sheerin first design the horn straight, then piece the folded horn together
by conserving the areas.

See: Collaborative Tapped horn project, post #1490 for a step-by-step on folding a Tapped Horn.
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Old 21st January 2009, 07:55 PM   #215
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xstephanx
For your purposes, No it wont matter. At that size I would brace it.
I assume its 35" tall by 20" wide. So a "+" brace would be good. Though I wouldn't use a 2x4. I would make something from the scraps you will have.

Should be able to make it in a day or 2.
If you don't have a table saw, you can build using only 90 degree cuts.
Even if you need to physically angle a board, that is fine. Just fill gap with caulking. You can even "step" the sections so there aren't any angles at all. Long as the throat, mouth, and length are correct and each segment is expanding. You will be good to go.

I will already predict the Cops being called.
Less you don't have neighbors. Or are in a a basement.
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Old 21st January 2009, 08:14 PM   #216
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Flipc

youre going to laugh, but as a teenager in suburbia, i am surrounded by old people with poor hearing, even when me and my friends would jam in the garage, with guitar amps cranked, ive never once had a noise complaint. although well see about 130db at 40hz in the living room...those long waves have a bad habit of going through barriers, and that room has two huge bay windows(one floor to cieling)

i have a table saw, and also a good circular saw, which i prefer to use with a saw board 90% of the time, i find that the coupling between the board and the saw is usually alot more rigid not to mention longer) than the fence on an entry level table saw.Not to mention i dont feel safe around table saws, if it was a milling machine on the other hand

caulking will be used, and i will brace the mouth in a cross with scraps, as per your reccomendation(with a little bit of thought its better than my idea)

Don, that method is what i tried to do last night, my approximation is made by calculating the line length so far, and making sure it corresponds with the surface area between the end of the board and the wall at the turn(does that make sense?)

thank you guys so much for all the help, its been too long since ive had an exciting speaker project on the go!
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Old 21st January 2009, 09:30 PM   #217
FlipC is offline FlipC  United States
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Yes
You weren't pushing out the low end in your garage so the sound dissipated WAY before it go into your neighbors house. This sub is gonna SHAKE their sh!t.

Be sure to post some pics when
your done!
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Old 22nd January 2009, 02:05 AM   #218
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oh i dont think ill be able not to, at 585 litres this thing aint gonna be tiny!

also, i see alot fo tapped horns have a plate infront of the driver, with a hole that is < SD, is that supposed to be the same measurement as s-1? or do i not need it? whats going on with that thing?

things are slowly assembling in the basement for construction....caulking....coarse thread drywall screws... circ saw, only thing thats really missin is OSB!
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Old 22nd January 2009, 05:02 PM   #219
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OH and I wasn't suggesting you use OSB.
Unless you want to test first. That was for just a guy. Cheap way to build a test box. You want to use really good plywood. I would say MDF but at that size the weight saved from plywood will offset the cost.

As far the "have a plate in front of the driver"
goes. In HornResp look at your schematic diagram. See the area at the throat?
Click the image to open in full size.
See how the driver is partially covered?
That is what this is. Sometime also it will be a compression chamber
before actual horn. But that is up to your design. The schematic gives you the dimensions. Though I wish you didn't have to mouse over things to get them. The compression is part of the throat so must be correct as possible.


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Old 23rd January 2009, 12:18 AM   #220
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you lost me a little there my schematic doesnt really look like that, the circles seem contained on either side. are you talking about how the "sides" of the horn create a chord going through the circle? and then the area of the opening infront of the driver would be equal to the area contained within the chords? this seems to be the only reasonable number i can generate out of that schematic

also, the OSB is due to cost, im out of school and currently still looking for a job, and this is only to hold me over at some houseparties until i build a real PA system(happening before the summer). in other words, the goal of this deisgn isnt so much great quality as great quantitiy between the critical range for electronic music (mainly electro/fidgit house) so as much energy as i can get between 40 and 120hz. before i stumbled on this tapped horn idea i was going to build a 6gth order bandpass, with 40 and 80hz tunings(holy groupdelay!) so id tend to think even an OSB TH would be better.

the osb is 15$ a sheet, the fir plywood is 40(!) they also have spruce plywood for 20 a sheet, but it has lots of voids in the plys, and i think id lose more SPL to that than i would losing it to some somewhat flexy OSB.

also ive heard a couple times that OSB is good for subwoofers, lots of people build IB manifolds out of it too.

mdf is a big no no, im not looking forward to the idea of a 200 lb+ box...
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