How severe is port resonance in 4th order bandpass?

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wonderfulaudio

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Joined 2018
#1
Hi,

I would like to discuss a couple points regarding the port in case of 4th order bandpass subwoofer:-

1747483992539.png

1) How severe is the port resonance? The simulation shows a dip at about 180Hz, the reason why I ask is that I've read that simulation exaggerates it, it may actually not be such a deep null.
2) Can this slope before the first port resonance null (between 100Hz and 180Hz) be used as an acoustic crossover, the second peak is at 363Hz, I could always use a crossover (2nd order low pass ) at 200Hz only for that.
3) Is that peak at 363 Hz also exaggerated in simulation?

Warm Regards,
WonderfulAudio
 
#6
I’m dumb…. Sorry. I saw ‘band pass’ and ‘ port resonace’ and got excited and posted my 6 th order parallel(not 4th….)

The full wave length gap before all the 1/4 wave junk as a crossover region is always intersting to me as well .

I did notice 345.6/meter/second /192hz is the full wave length of the entire enclosure (front to back of driver) of 180 cm?





…
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#8
You don’t have a choice when you’re concerned with those resonaces because they conflict with your other speakers in the XO region

Or,

Build TL or higher order TL stuff and you’re dealing with a bunch of junk @ 3x Fb that must be addressed
 
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#12
^ Maybe the excess group delay is the reason? Higher order filters gives more phase offset and group delay. Best integration seems to be achieved when the different freq band drivers has equal phase offset at crossover frequency (first align time-of-flight = time delay for each driver.) Easiest done with DSP.
 
#14
I tried to ‘fix’ the green high order qw bandpass box (roar) to go quiet like the red Helmholtz bandpass box does on its own acoustically and the group delay was goofy as heck.

I dunno what is worse, ringing pipe resonaces or lots of group delay. Or both 😱

These aren’t very useful subwoofers as the sound is to adultered with audible versions of fetanyl and methamphetamine 👽🚀
 

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#18
"Normal" filters can only add phase shift to the response, what Booger might need is something that could subtract phase shift. As I said, I really don't know how, but maybe CamillaDSP is able to handle such task? Then all ported designs could get rid of the nasty group delay smearing transients 🙂
 
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#19
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Is it ‘more’ advantageous to try to create (acoustically) these big areas of cancellation in our subwoofer designs instead of trying to fill them in with messy stuff(horn shape instead of this ‘stepped’ resonator shape ) and then erasing it electronically?
 

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#20
Booger weldz said:
Is it ‘more’ advantageous to try to create (acoustically) these big areas of cancellation in our subwoofer designs instead of trying to fill them in with messy stuff(horn shape instead of this ‘stepped’ resonator shape ) and then erasing it electronically?
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I would think so, a combination of electrical and acoustic filtering, then phase and delay adjusted with DSP. A bandpass design seems the easiest wrt acoustic filtering
 
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