There's 2 aspects to that:
- "Punchy" in the "fast bass" sense which is likely more about the upper bass which in turn likely depends on the crossover integration more than anything else.
- The transient response, i.e. how "blurry" or "tight" is the bass which can have to do with the damping. In general sealed boxes have better transient behavior, but an "undertuned" ported box can sound quite tight and a too-small sealed box sound boomy.
Very much appreciate answers and explanation:
Two XO-less speakers run fullrange, coonected in series, is the combination minimum phase? Connected in parallel? Different cabs? Pointing in different orientations? Different drivers? Over what frequency range?
Or does the concept only apply to anechoic infinite-baffle single-point-source on-axis omni-mic measurement between Fs and breakup -- others need not apply?
Last edited:
Nonlinearity is not the opposite of a linear system, although 'linear' has a few distinct meanings one of which is the absence of nonlinearity.
Otherwise you make a good point about analysing each aspect in isolation, in combination with being aware of the significant behaviours.
Did I see Barkhausen noise coming up again? Let's add all kinds of noise a loudspeaker unit in it's enclosure produces: resonances in cone, basket and enclosure (both walls and cavities), like rubbing/chuffing and other noise often accompanying bigger displacements. I bet they can be described to a great extent by analogies. Might even be true for Barkhausen noise. Did I mention thermal compression? Is it relevant? Who will say? In the end, the minimum phase behaviour is(or should be) the dominant behaviour, from a perceptual POV too.
A linear minimum phase system is causal and stable with an inverse that is also causal and stable. Generally a linear system can be split into a minimum phase part and an all-pass part which has a constant magnitude but changes phase. So to answer your question you need to look for physical mechanisms that introduce delayed repeats of the signal. Reflections in a room, crossover regions with drivers different distances away in different directions, etc... At high frequencies a wideband driver will have parts of the cone moving in different directions leading to all sorts of phase chaos. A coaxial with largely pistonic moton is likely to be a better bet w.r.t. to increasing the minimum phase component.
Having said that in well designed speaker systems the all-pass part (and the nonlinear distortion part) can often be small enough to be inaudible except over frequency ranges where room reflections are intrusive. Even then our binaural hearing system can sort out some higher frequency sound interference that look poor when measured with a microphone but don't sound poor. So in practise what matters is the audibility of the the phase mangling going on not whether any phase mangling is going on since it will be. Not unlike like ported vs sealed w.r.t to group delay when listening to music in rooms.
Yes, both are good ways to make opposed arrangements, however both do require some extra cabinet volume/size. Which is a bit of a bummer.
I've made both.
And two other versions of double 18"s ported.
Standard singles with corner ports I could stack,
and a big whooper of a double with downward firing ports.
And the last double 18, the first 18" subs I built, single sealed that could stack.
All of these used the same driver, the bms18n862.
All the ported were tuned from f-3 at 30Hz to f-3 at 25Hz, with close to the same port velocity.
As I got better at building the subs, i was able to keep getting a little lower than 30Hz from the starting standard ported with corner ports.
All have used steep 96dB/oct lin phase low passes at 100Hz....so nothing beyond sub frequencies to muddy up comparisons.
Best comparisons and measurement are always outdoors, that's a given imo.
But how they end up indoors is what counts most justly based on listening time. So far outdoor and indoor comparisons have essentialy been equal, after fiddling with indoor placement some. This is with regard to a single sub setup/stack only.
As said earlier in thread, it didn't take any time for me to realize the advantage of ported vs sealed, once sealed was EQ'ed to match the standard type ported boxes.
From then on, ported comparisons have been more about how the boxes felt, the visceral tactile feeling of the bass both steady state and transient.
Steady state, I haven't heard enough difference to think I could match any kind of blind test.
Transients are another story' The big single box with the downward ports has been the worst. I think good old standard corner ports , stacked, have been slightly the best. But not enough to forego the advantage of opposed vibration reduction found in the slot loaded or the 45 degree guy.
I know most will probably scoff at the 'empty beer can test' i floated for measuring transient impact..
But honestly, i've found it to be a hell of a good objective measurement.
An empty Monster Energy drink can is best I've found....the aluminum is so thin and light, it doesn't take as much SPL to get movement.
Personally, how much the can moves at carefully matched SPL and distance, is a damn good measurement imo.
An aside....I've found multiple subs make a can dance in place, or maybe hover heading somewhere. Whereas a single sub, mainly moves the can in straight direction.
fwiw, a lot of anecdotal i know...
But i'll also be so bold as to say, at least outdoors, they are some of the best measuring subs i've seen, both by mic and beer can!!!! haha
i do like to experiment off of the beaten track...
I'm not sure if the VAS is a typo, as it's similar to other drivers in the range; the recommended closed box volume is .75 cubic foot for a f3 of168.6 Hz, I think the idea is to use the driver all below the frequency of resonance, and to throw lots of watts at it. If it's a rubbish driver, don't be scarred to say so, you would save me some cash and the effort of making a pair of boxes. I'm thinking the best use would be in the bottom of some tower speakers with a 4 inch full range at the top, the full range powered by a 3 watt amp, the 6 1/2 inch powered by a 300 watt amp.
