thanks guys, understand now. the thread is so sloppy, hopefully the good information gets through to all who need
1) where is the best place to put resonance? why not right above your working range for the subwoofer (maybe it's not possible)?
2) any way to use port resonance to be enhance SQ of your system?
my favorite box sounded echoy and starting to wonder if it something to do with resonance? the notes maybe seemed to last after being played. it is something which to me sounded really good. maybe it was just luck with the box build, amp, speakers, and car cabin. maybe it had something to do with the glass bottle idea?
fantastic, don't think you can go back and change it. it might throw newbies off in the future!
1) where is the best place to put resonance? why not right above your working range for the subwoofer (maybe it's not possible)?
2) any way to use port resonance to be enhance SQ of your system?
my favorite box sounded echoy and starting to wonder if it something to do with resonance? the notes maybe seemed to last after being played. it is something which to me sounded really good. maybe it was just luck with the box build, amp, speakers, and car cabin. maybe it had something to do with the glass bottle idea?
fantastic, don't think you can go back and change it. it might throw newbies off in the future!
SS,
What vent air velocity does Bass Box Pro use for optimal port length and diameter suggestions?
Art
Unknown, it happens in the background. You specify / select tuning parameters in the box section, and under the port section it has a place to enter your own parameters or use the magic button to auto calculate parameters to achieve Xmax at a given frequency.
That is what makes me think it is trying to optimise based on port velocity rather than a tuning frequency. Will try do some screen shots tonight.
thanks guys, understand now. the thread is so sloppy, hopefully the good information gets through to all who need
1) where is the best place to put resonance? why not right above your working range for the subwoofer (maybe it's not possible)?
2) any way to use port resonance to be enhance SQ of your system?
my favorite box sounded echoy and starting to wonder if it something to do with resonance? the notes maybe seemed to last after being played. it is something which to me sounded really good. maybe it was just luck with the box build, amp, speakers, and car cabin. maybe it had something to do with the glass bottle idea?
fantastic, don't think you can go back and change it. it might throw newbies off in the future!
Indeed! It needs a serious revamping by a moderator. In the future, please limit text modification to a minimum since it makes it too tedious to extract the actual text out of it to quote and why I copy/pasted off the thread post.
As a general rule, you want Fb to be at or below the lowest frequency one wants to reproduce at any significant SPL. For a no compromise HT then, only a very low Fs, multi-driver IB will do since some movies have LFE content down to ~10 Hz, rolling off to near zero Hz [DC].
For most music recordings though, ~42 Hz suffices, though there’s enough recordings that go down to ~27.5 Hz [the lowest note on a large piano] to warrant considering this as the lower limit for all but large pipe organ symphonies and/or those that have some digital LFE, which dictates a ~14-16 Hz Fb, though many ‘cheat’ by tuning up to a ½ octave higher [~22 Hz] and use a high pass filter to protect the driver
Well, what one can do with a vent system to enhance a speaker’s performance depends on what constitutes an improvement.
For instance, the pioneers of audio recommended critically damping the vent to audibly remove any transient overshoot of an under-damped cab alignment [‘bong’/’echo’] to achieve a lower distortion, more accurate reproduction; while others used large, long vents to add some euphonic harmonic distortion in the upper mid-bass, lower mids above the cab’s upper mass corner frequency [~2*Fs/Qts].
Then there’s the big vent reflex [BVR] that historically has been erroneously referred to as a back loaded horn [BLH], which when properly designed will offset any baffle step loss [BSC] without the need to electronically trade away some efficiency to get a tonally balanced response down to Fb.
Specific to a speaker placement up against a wall or in a corner and especially in a car app, a maximally flat cab alignment will be under-damped to a greater or lesser extent in room, so with cars typically having a very high room gain, you probably either needed to seriously damp the vent and/or tuned it lower or even plugged it up.
Frankly, I skipped over the whole Helmholtz/glass bottle ‘thing’ since what’s important to know for understanding how it applies to reflex speaker design is that the cab [bottle] either has a ~uniform particle density [no eigenmodes] or in the case of a high aspect ratio one, it’s a ¼ WL resonator [closed pipe]; while the vent [bottle neck] is a ½ WL resonator [open pipe], so the driver excursion at some point excites the vent enough [whistles/blows] for it to begin resonating at its fundamental:
Resonances of open air columns
I find this little animation very instructive as to how a reflex works: Essay
GM
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