Low mid to go underneath Unity Horn

I have four 12NDL88 drivers to put below a unity horn I have designed. My aim is to do 150hz up to around 400hz which is why I have gone for angled baffles to move the acoustic center of the drivers closer together.

I have currently got a port either side to allow for space behind for the 12" driver but I might try and get it to fit with a single port on one side.

I started off by simming in hornresp to get something vaguely what I want.


I then drew it up and simmed it in Akabak BEM and my output is wildly different, I have checked the volumes and areas a few times. I checked the volume using Akabak by adding everything to the repository then using the meshing to calculate the volume. Some of my triangles are maybe a bit thin but I will redo it sometime, the LEM sim is the same though.


The impedence nearly matches in both


I have also drawn it up in LEM in Akabak, without the angled baffles, to compare and got the same results as BEM


Does anyone know what the reason why the sims are so different? I kinda want to build it and measure it to see how it will do


Joined 2003
At a glance, your build is a (very crude) BP4, which is what you ideally want, though as I noted to some early Unity DIYers, it ideally needs to 'ring' @ the BW's mean, i.e. (150*400)^0.5 = ~245 Hz for best overall pace, rhythm & timing (PR&T) with the baffle/slot designed to match the Unity's polar response.
Finished the build and did some vague measurements, it was pretty good. i need to do some off axis measurements of both but need to sort out access to a laser cutter first.

The measurements are on my other laptop, I will sort through them and post them later.





As a test I lent it to my mates for an event to use as a monitor, had some really good feedback about it

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