Ported Horn Kick | Q^be15

Hi,
I'm working on a new project, a 50*50*50cm 15" kickbin (125l).
As the size is limting the length of the horn to 60cm, I decided to go with a ported backchamber.
Here is a first simm with the B&C 15CL76:

I got one problem with the modelling in hornresp, tho:
How should I modell the throat area (Marked with '?').

Option 1: Specify the whole area as the throat chamber.
Option 2: Specify the driver bowl as a TC and add a very short duct segment before the offset driver input and a longer duct segment after.
Option 3:Specify the driver bowl as a TC and add a duct segment after it.

Which one resembles the real world the Best?
I went with option 3 as it was the most pessimitic and that's my nature

Also I got a diffrent idea for loading:
Port the Back chamber in to the Throat chamber. I guess it would act like a Bass reflex cap, with a straped on horn in front, resulting in a high bandwith and good efficiency.
I got this idea from Föön; they have a 21" 2.2m horn, that has an F3 of 26Hz with a single cap (also a very small mouth).
Any Ideas how I can modell this in Hornresp? Did anyone ever hear of that loading before?

Thanks in advance!

Hi,
Last post was ver 0.03, which was a rough guess.
This is ver 0.04 and is based on the CAD drawing and fits the 125l perfectly.

search for klipsch lascala, lots of www content covering those incl. HR inputs and more info.. if you want to use similar cabs on kick duty i would skip the ports and deal with the required horn size to cover your needs, rather than sacrificing/losing the good impulse response/low group delay!

OIL wrote: Hi genome, I'm not to familiar with ports as I always avoided them... Port is tuned to 75Hz. Is there any difference with round ports compared to rectangular if ap/lpt is exactly the same?

With 2.5cm on port the plywood cut on angle would be close but you would also probably have to add distance cause of start shape. Also if you want to make very awkward shape with widtch much longer to height it should tune even lower. Its better for impulse ofc but you cant tune lower here because port 2nd resonance will got into bandwidth(unmasked). Basicly already surface of the port is very very small.
If you want to compare port shapes sim compound horn and use rear as port the result of very not tube-like looking one would be similar to normal one in terms of characteristics (not frequency).

OIL wrote: I can't find anything in the Help with those keywords. I suspect you mean that l34 is parabolical; I don't understand why. Could you explain?

"A parabolic (Par) flatre should be used..."
Ctrl f in help there is more.

Are you sure that driver will survive horn loading?

Because TS parameters are on the very edge of what a 15 made for horn loading should be.