Horn design questions

I have now begun the seemingly herculean task of designing and building my own folded horn for the V18-1000. I am aiming for it to reach 35hz in groups of 4 with as much SPL as possible playing Drum N Bass, Tekno and other kinds of rave music. Size is not too much of an issue for me so am prepared to make it very large as I understand this is what it will take to design an awesome horn. However my masses of research has raised a few questions I cannot find answers to. Firstly, I understand the contour I want to be using is exponential but I am confused as to how to actually design the folding in this shape as all the types of contour seem very similar when comparing actual horn designs. How do I know for certain that it is expanding at an exponential rate? Secondly, has anyone used this calculator:

Upon putting in my specifications it has given me some rather interesting results.  

Thanks in advance

Last question first, and easiest - that's the mouth area not any of its linear dimensions, so not too scary - remember area = width x height, so if you made it square it'd be 88cm per side. If you went for a conventional rectangular mouth you could have it around 110 x 70cm.

<Edit> - Ha! I took so long with the rest of the post that someone beat me to it & answered this already!

Next, I haven't used that calculator so I can't tell you if it means that's the area for all 4 drivers or just one. Did you input the TS values for one driver or four?

However, looking at the general values, I think it might be just one.

And to make sure your plan matches the target expansion rate, you'd simply calculate the required area at regular intervals down the length of the horn, and make sure your plan matches those values. (Any decent horn calculator will do that first part for you  )

Oh, and rather than trust a calculator like that, I'd be much happier using Hornresp.

Here's a prediction of the sensitivity of a block of 4 horns with the V18-1000, driven with one Watt split between all 4 drivers. Each box would be very approximately 1200 wide, 750mm high and 900mm deep, so about 40% bigger than a WSX. (NB: This was just a quick play, so I'm quite sure someone else will be along with something better in a bit - particularly as I haven't even attempted to explore tapped options etc yet.)

HTH,

David.

Yes.

e is mathematical/physical constant.

x is just function variable in function e^x. It represents length so basicly your exp12 value.

Maybe using different words:

The whole trick is to find how to scale e^x so it will spit out the values of cross sectional areas. Than x's will be proportional to lengths(exp12) values only moved by start value.