Not all is gold. This is what you can easily get when you're not careful enough. 😱
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Just put a bit of felt “upstream” of the midrange ports. That should reduce the diffraction effects from/on the HF, at the cost of a minor bit of efficiency.
Sounds familiar. I'd pin my hopes on this one, with a top-notch free standing horn above it:
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7246372
There's still nothing I wouldn't like about that design. (Not necessarily with a 15", that was just an example. It could be much smaller.)
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They are already available, it's just that without a LE model (TS parameters of a particular driver), it's probably not very meaningful.
This is a general, constant acceleration model:
Yeah that dipole with horn top design could be a nice match. Would fit perfectly with a synergy horn on top 😜 for low xo to the woofer. Keep going! 🤯
Without actual parameters you have no idea about the absolute sensitivity and excursion demands it brings, i.e. how big/small midrange driver can be used and what's the low frequency limit - that's what I'd be interested in.
Fortunately, it's not difficult to do.
Fortunately, it's not difficult to do.
With the 2 and 4 simulations I'm only seeing differences in the 5-10kHz range. The h results look like numerical artifacts as nothing has changed in this plane and they are at the highest frequencies in the simulation. Its interesting though that below 5kHz I am not seeing differences which suggests it's posible to 'hide' the ports from the HF.
Do the directivity spikes between 7kHz to ~9kHz happen because those frequencies disappear into the port? If so, could you overlay the port with a material that stopped those frequencies from falling in the hole but allowed lower frequencies to pass freely?
^ I've often thought that this is worth a try. Almost impossible to simulate a thin sheet of say silk (accurately,) but it could easily be done experimentally.
Why do you think that the ports in the upper/lower wall shouldn't affect horizontal polars?
Here's a similar model again, with and without the ports shown.
Without and with the ports (horizontal polars):
Below the non-normalized data, smoothed with 1/6oct -
Horizontal polars:
Vertical polars:
BTW, closing the interior of the horn into a separate subdomain gives noticeably cleaner results -
Without and with the ports again (horizontal polars):
I'll try different port shapes and sizes.
Without and with the ports again (horizontal polars):
I'll try different port shapes and sizes.
What about a greater number of smaller holes? I even think I've already seen that somewhere. At what diameter of the individual holes would frictional losses become a real issue?
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