Now I don't have great expertise with horn folding so I'd appreciate some critiques here. This was done in Blender and if there's enough demand I'd be glad to show everyone a walkthrough on how it's done, although I have yet to fully figure out how to export the data for CNCing but it does look like there's a way to do it, and for further context on the mouth and orientation of the horn you can see Citizensc's Akabak sims from an earlier discussion on the topic:  http://forum.speakerplans.com/bc-horns-from-standard-flhs_topic105665_page1.html" rel="nofollow - https://forum.speakerplans.com/bc-horns-from-standard-flhs_topic105665_page1.html

So some notes; a -3db of about 30.5hz, this max continuous SPL is driven by 1700 watts (that's just 425 watts a driver). Is there any reason that using a fair bit less than the rated power would be a negative? The 15NW is rated 1000 rms, 2000 peak which leaves us quite a bit of headroom for peaks. Displacement however hits xvar of 11mm at 3400 watts which is only 3db of headroom. My question here is what's the risk of hitting 14-16mm of displacement on peaks for 6db of headroom? I'm assuming xmech is substantially above xvar so distortion on peaks if you're really cranking these could be acceptable atleast for a little while. My intention here though is not really to ever run these at max output; 130-137db is probably plenty for my needs (50-500 people max, dub/dubstep/dnb/funk/hip hop/house and pretty much anything else that might use sub around 30hz). Group delay with filters enabled is a bit sub optimal, however this can be reduced to about 35ms at 32hz with LW filters and for most front loaded horns I haven't really seen anything that confidently beats this. Even the new Paraflex designs seem to have similar group delay. Compression ratio is 2.6. Current box dimensions are 46" by 29.8" by 20.5" (I'm really trying to save as much space as possible). Also similar to the BC215 design I'm planning on placing some corner reflectors on the top so I can cut handles directly into the frame. I'm also really hoping these will come in under 150lbs each, but I know this is probably way too optimistic especially with bracing.

SO any thoughts/questions/critiques here? I'm really looking to pull the trigger on buying parts either this week or next. Been learning and planning for about 8 months or so now and would like to have atleast a few of them built before the end of the year, but this is my first ever speaker build project and the last thing I want to do is rush into things and waste about 2-3 gs. Also as just a final note I’ll be cleaning up the precise folding and am curious about the best way to overlap the borders around the bends? Specifically the 180 degree bend you’ll see the sections are a bit sloppy.

interesting post from Danley

https://www.diyaudio.com/forums/subwoofers/263812-danley-bc-subs-reverse-engineered-9.html" rel="nofollow - https://www.diyaudio.com/forums/subwoofers/263812-danley-bc-subs-reverse-engineered-9.html

toastyghost wrote: All Danley sub measurements are carried out on a large car park at 10m in 2pi (ground plane) with 28.3V input, then scaled back. It is however designed to be used in pairs, or a single box in a corner for say an install.

I believe in the spec sheets you’ll see “measured in 1/2 space” (EDIT 2pi**) with the same voltage and distance you described; my question is and Ivan Beaver sort of briefly explained this to me but why aren’t they simply measured at 1W/1M again? I’m also wondering if they’re saying 1pi simply because of the size of the face of the stack?

Very curious about this!

Looks great, certainly easier movement splitting the horn in 4.

1. Getting your geometry in to the software, if you are feeling masochistic you could draw the whole horn in AKABAK 3 by setting coordinates and creating planes from those coordinates. I think the more sane method is to draw it in external software and import the drawing in to akabak. Make sure the drawing is as minimal as possible, I only include geometry that matters acoustically, eg. I don't draw internal cavities in detail. 

2. You then have to define a lump element network which basically defines the electromechanical properties of the driver.  

3. You then have to set up all the measurement stuff, which is basically like setting up a mic array in the software. 

The learning curve to all this is a bit steep but once you get over it you start to realise you can sim pretty much anything you want in the software, including the room the speaker is in. It took me hours to get my first sim working but now I can build one from scratch in about 15 min. 


I have been thinking about making a little tutorial series that covers the basics needed to get started, it wouldn't go in depth as I don't feel qualified to do that, I may mislead people. 

If I do, it wont be soon, I have been super busy since getting out of lockdown and moving back to my home city, so much so that I haven't had time to prototype my unity horn despite having the components :(  

Ps. The HF1440 is HUGE!! I have big oafish hands and it makes them look tiny. 

I modeled moving the volume of the cone around a bit and not much changed, but I just want to confirm S1 should start half-way across the driver, then the volume shaded in yellow here including the cone volume should be added to vtc?

Here's some possible stacking options, although I think the whole point of this design is to really use the perpendicular mouth for the low-frequency extension. I suppose you could use this as a seriously overpowered kick bin in the conventional orientation?

Here’s the inputs incase anyone sees anything that looks off:

Can’t say enough how much help this community has been. Started learning everything probably just before the start of the pandemic and I'm really hoping to build the first box and see/hear/feel the results. I’m also hoping this design will be able to keep up with the newer paraflex designs...

This does use up a horn section though, so you may need to condense your current s2-s4 into one section.

This doesn't always make much difference, but I'd try it both ways just to be sure.

Condensing S2-S4 to keep offset driver mode with the perpendicular exit of S5 did seem to make a decent difference in the sim but I would imagine that’s to be expected since that would be quite a drastic change in the expansion rate throughout the mid section? This particular horn seems to benefit a lot from a very slow expansion rate to start really until S3 to S4 (the traditional end of the horn).

And here's another look at the design where VTC is highlighted. After reading through previous posts including citizensc's 15BG horn I believe this should be the correct approach in order to free up the additional segments:

The last "gamble" on this design that I'm thinking is really S4 - S5. Currently I have S4 - S5 as half the width of the cab (24.1cm), but I've experimented with slightly more and slightly less and each scenario is pretty close. This is also assuming that the path touches S4 at the bottom left then moves out directly towards you, but I've experimented with a shorter path and smaller S4 area and it would also take quite a difference to see drastic changes. If there's any thoughts here I'm all ears!

As far as orientation it is still a bit of a guess with respect to directivity but the idea would be to always use the smaller exit for the lower extension. You could consider it a corner horn as well since the corner would cover all exits but S5.

Akabak 3 is almost totally different software to the classic Akabak which causes great confusion.  Akabak 3 includes a BEM simulator and an LEM simulator which can be coupled.  Whereas Akabak was only an LEM simulator.  Hornresp is also an LEM simulator but with a more limited interface than Akabak which makes it easier to use but also means some very complex boxes can't be simulated.  The software you want to simulate a BC horn is Akabak 3 as you need BEM simulation to take into account the mouth shape and coupling of box mouths.  The linked thread uses Akabak 3. 

There are some video tutorials around for Akabak 3:

https://www.youtube.com/watch?v=I5dvgBgtbos" rel="nofollow - https://www.youtube.com/watch?v=I5dvgBgtbos

(I haven't used this one just came up in search)

I would recommend following some to get an idea of what it does and the interface.

Also the program includes some examples.  I wouldn't say its the easiest thing to learn but its well worth learning.  The only limitation of the free version is that you can't save results so have to re-solve the model every time you open the file and want to look at the results.