Hi all,
I am designing a subwoofer for 20-80hz region to complete a sound system I’ve bought, I’ve got a great interest for horns but think my space requirements are too small for a folded or tapped horn, but I really want that aggressive look of folded horns/scoops/bph
my plan is to design a 6th order band pass enclosure with rectangular ports flaring i guess in a conical ish way- straight lines expanding to a larger mouth
I’m really struggling to find how to model this/ find forum posts or literature on how this affects port tuning, everything I’ve seen is for exponentially flared circular ports which only affects the air velocity, I’m not sure how the length and different volume of air will affect the tuning of the port. The only thing I can think of is plugging a bunch of differently flared boxes into akabak and see what happens but this will take days if not weeks as I’m not very proficient in akabak yet.
I’ve read the explanation on free speaker plans about bandpass enclosures under 1.67m in horn length but need some more help understanding before I can design
So: how does flaring a rectangular port change the tuning? With the different volume how does that affect the tuning? Does the vent have to be the same length, or does it have to be the same volume of air?
Thanks in advance, it’s a silly question I know☹️
I am designing a subwoofer for 20-80hz region to complete a sound system I’ve bought, I’ve got a great interest for horns but think my space requirements are too small for a folded or tapped horn, but I really want that aggressive look of folded horns/scoops/bph
my plan is to design a 6th order band pass enclosure with rectangular ports flaring i guess in a conical ish way- straight lines expanding to a larger mouth
I’m really struggling to find how to model this/ find forum posts or literature on how this affects port tuning, everything I’ve seen is for exponentially flared circular ports which only affects the air velocity, I’m not sure how the length and different volume of air will affect the tuning of the port. The only thing I can think of is plugging a bunch of differently flared boxes into akabak and see what happens but this will take days if not weeks as I’m not very proficient in akabak yet.
I’ve read the explanation on free speaker plans about bandpass enclosures under 1.67m in horn length but need some more help understanding before I can design
So: how does flaring a rectangular port change the tuning? With the different volume how does that affect the tuning? Does the vent have to be the same length, or does it have to be the same volume of air?
Thanks in advance, it’s a silly question I know☹️
Flaring the port increases the end correction value, lowering the tuning.
L'Acoustic appears to have proven their laminar flow square or rectangular exit ports have less loss ("port compression") using both less length and volume than an equivalent round port, in spite of the predicted port velocity being higher.
So a shorter, radiused port with a reduced exit dimension would give the equivalent Fb, using less volume.
https://www.diyaudio.com/community/...h-push-slot-loaded-build.409197/#post-7602789
This thread goes into more detail:
https://www.diyaudio.com/community/...sonance-absorbers-and-port-geometries.388264/
This one gets into how flared ports can be simulated in Hornresp, probably easier than Akabak:
https://www.diyaudio.com/community/threads/flared-br-ports-with-hornresp.414675/#post-7727515
Well, as long as the port air velocity isn't too high and causing compression and/or port noises.. The former causes high losses and increase of the port resonance, the latter causing Thd. So the minimum port area does matter a lot. Many cheap PA speakers use the occurring compression to limit the bass driver excursion and to 'cheat' on the lower fr, max spl and power capabilities/respectively distortion figures, combined with 'cheating' power compression.