Actually the location of the port ends that are inside the box can made a difference, not around Fb, but at the harmonic resonances. At least according to my sims... 🙂
As I couldn't get the desired behaviour in the simulations, it got obvious to me, that I was lacking understanding of the theory behind truncated horns. I went back to overthink the whole concept, reread your comments and went a little deeper into theory. And I found a paper by Marting J. King that really helped my understanding of the subject:
http://quarter-wave.com/Horns/BLH_Design_Article.pdf
My biggest misconception was, that a small truncated horn, or even my tapped horn, would be much closer to actual horn behaviour than it actually is. In reference to the paper, both are better viewed as expanding transmission lines, and therefore quarterwave resonators. Which is exactly in line with the observed behaviour in my simulations, when i tried to lower the tuning by changing the expansion rate. Lesson learned: So there is no impedance matching happening here (at all?) and a resonator is the not the way to achieve dry, punchy kick bass.
There is one way to make the small thing behave like a horn: I could achieve a big enough mouth area for impedance matching (-> horn behaviour) down to around 70Hz, if i put it beside a wall, as mouth area is virtually mirrored. BUT, that won't work in the designated room.
I hope someone else can learn from my little exploration here.
I will now do the following: I'll build a "normal" vented box and see if I like a QW-resonator or BR better for low end extension, but open a new thread for that project. Thanks everyone for the input again!
http://quarter-wave.com/Horns/BLH_Design_Article.pdf
My biggest misconception was, that a small truncated horn, or even my tapped horn, would be much closer to actual horn behaviour than it actually is. In reference to the paper, both are better viewed as expanding transmission lines, and therefore quarterwave resonators. Which is exactly in line with the observed behaviour in my simulations, when i tried to lower the tuning by changing the expansion rate. Lesson learned: So there is no impedance matching happening here (at all?) and a resonator is the not the way to achieve dry, punchy kick bass.
There is one way to make the small thing behave like a horn: I could achieve a big enough mouth area for impedance matching (-> horn behaviour) down to around 70Hz, if i put it beside a wall, as mouth area is virtually mirrored. BUT, that won't work in the designated room.
I hope someone else can learn from my little exploration here.
I will now do the following: I'll build a "normal" vented box and see if I like a QW-resonator or BR better for low end extension, but open a new thread for that project. Thanks everyone for the input again!
As Brian said so many times - when we plan some kind of box we always must consider same size and speaker in BR alignment and see if we actually gain something. I will love to see your thread and follow your findings.
Take a look at the thread below and read author conclusions on post #26. It may save you some time.
https://www.diyaudio.com/community/...some-other-problem.406237/page-2#post-7544813