I’m starting to figure that out I think as the CSS isn’t modeling the best either but not bad. I’m wondering why that is without doing any research yet.
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Brahma 12, but I get a very nice FR curve in 1.0 ft³ tuned to ~33Hz via a pair of 10" PR's
(so I guess I disagree with the Brahma wanting a large enclosure; generally speaking the figures of merit for vented enclosures [Qts^3.3*Vas*20] ≤ Vb ≤ [Qts^2.87*Vas*15], for a "maximally flat" vented enclosure volume with the best F3, with an appropriate tuning frequency)
Here is my Akabak model (bandpassed 20Hz/100Hz):
https://drive.google.com/uc?export=v...nsKUdK14cKe2xn
In fact, the current Brahma iterations have Qts values perfectly suitable for vented enclosures. Even the Brahma 15" has a very respectable Qts = 0.45.
Oscar, I didn’t think about a passive radiator and I haven’t spent much time checking the Thiele Small Parameters to see if they are completely correct. I just loaded to specifications that were already in the program and let Bassbox Pro select the ideal box size. Later on I can revisit that and check.
Thanks for posting that information. I definitely don’t want to mislead anyone with incorrect information.
Well the PR part doesn't change anything really, as the response will be nearly identical to the standard vented box, but knowing the parameters is very important. But as you can see, you can get an awesome, pretty flat 4π response in as little as 1.0 ft bass-reflex (whether vented or PR), and probably even lower if you know how to factor in the cabin gain.
In fact, you can go as low as 0.7 ft³ and tune around 30Hz with dual 10" PR's to get a downward drooping response as frequency goes down, and it should yield a decently flat in-cabin response down into the 20's.
https://drive.google.com/uc?export=v...P5i_613dBn95l5
Turns out Oscar was right and I had the parameters incorrect so I re-ran the simulations with the correct parameters. I also modeled a passive radiator box too which was about 1 cu ft. See below graphs and comparisons to AF GB12 CSS 12. Also attached are graphs for group delay, vent volume, passive radiator, and a PDF with all the information for passive radiator. AF GB12 (orange) vs CSS SDX12 (yellow) vs Adire Audio Brahma (red) vs Adire Audio passive radiator purple.
Attachment 7693Attachment 7694Attachment 7695Attachment 7696Attachment 7697Attachment 7698
Your purple is "off" somehow. Or were you trying to mirror my cabin-gain compensated alignment that I posted? Even then it looks "off". What is your Vb/Fb for the vented alignment and for the PR alignment?
I like the ported over the PR graph for Brahma !
I was not trying to mirror anything you did but let the program dictate the alignment for the PR. The fb for the ported was 31 Hz and 1.8 cu ft. I had a lot of trouble getting a 4” round port to fit in anything smaller for the Brahma. The PR Vb was around 1 cu ft and I don’t remember the fb. I’ll have to open my laptop again to check, maybe tomorrow.