While admittedly limited to mostly "full range" speakers in the below $5K range, my experience is that sealed enclosures provide tighter, more natural bass than their reflex or ported counterparts. Unless bass is very tight and *right there* it quickly appears muddy to me. This is due to a loss of accuity in my lower frequency hearing from over exposure to industrial noise. The only speakers that seem to get it right are ones with sealed enclosures.
That response is quite correct (well, very typical of that design), and there is a simple physics explanation for it all. I will try and keep this short and sweet. Sealed (Acoustically Suspended) speakers are far more accurate, and overall, just much better designs. The downside is that they are more expensive and less efficient, ie. you need much more amplification to control a more difficult, more reactive speaker load. All else equal between the two designs, you will find that ported (vented) enclosures will provide looser, muddier, albeit louder bass. Hence, the cost of both the sealed enclosure speakers, and the associated electronic equip to run them, will go up astronomically if you want to run a high quality sealed system through the same frequency range and SPL (sound pressure level). Hope that makes sense.
..... Vandersteens "don't need no 'stinkin' enclosures". Ummmm Goooood!
While not disagreeing with the above, I find that vented can sound good in the bass, but it depends on the trade-offs made by the designer. But more importantly for me, I find mid-priced vented speakers usually breathe (pardon the pun) better in the midrange - ie. voices and instruments sound less strained.
Like all else in this hobby, everybody has their favorite, and wonders why anyone else would like something different than their personal ideal. You'll HAVE to make up your own mind through experience, and there are no shortcuts to experience.
Generally, I prefer a sealed enclosure over vented. However, for either type, it all depends on how well the designer has executed his/her design, and how well the apes in production can stick to the blue print. Sealed enclosures are usually more forgiving of small variations in woofer/enclosure parameters. A LOT depends on the particular "Q" chosen for the design for either type. Like Carl says...listen for yourself. Now how about a WELL executed transmition line enclosure......? (check your furnace filters because there could be a lot of flying fur on that topic)
My guess is that the quality of the upstream electronics has about as much or more to do with the quality of the bass than the enclosure type. Here's why. I was nuts for acoustic suspension for about 20 years straight. Yep, it made shopping easy. In the last ten however the highest quality, most truly amazing bass I've ever heard has come from ported types. Since I made the switch I realize I've never heard an acoustic suspension speaker with extended highs. Rolling off the high end makes for long term relaxed listening and really is quite pleasurable. But if you want it all, ported is the only place I've ever come close. The moral is, that in my effort to compensate for the sealed enclosures shortcomings, the whole system got better, so now it gets the most out of ported types. My advice? Select the Hype and the Look that suits you, then listen. Get an amp rated at the top of your choice's power handling capability and you're on your way. There is no substitute for the journey.
I am also looking at up-grading my system. All the speakers on my short list are ported- Montana KAS, JMlab Utpoia, the Sonus Faber. I have owned Maggies, transmission line and sealed speakers. The listening room has a lot to do with the correct speaker type. If you buy from a local dealer, get a 7-10 day return policy and try it out. I agree with some of the previous comments relative to synergy among the components, cables and speakers. Trust your own ears and experiment. Good luck and buy what YOU like.
It's not so much that I prefer sealed enclosures, but that I prefer the 6dB octave rolloff a acoustic suspension design typically has. Not all bass-reflex designs have a 12dB rolloff though; I had Dalquists that were ported, but had the first order rolloff - it formed a 'quasi-Bessel filter' between the crossover and the box.
The design decision to use an acoustic suspension enclosure or a ported one is completely independent of the voicing of the high frequencies. So, attributing certain high frequency characteristics to sealed enclosures or vented ones is incorrect. An acoustic suspension enclosure, properly designed, and mounted in the same volume enclosure as a ported one, will roll off more slowly below its resonance frequency, produce less harmonic distortion, or "doubling", and is less likely to have the characteristic peak or hump in frequency response near its resonance frequency. On the other hand, acoustic suspension enclosures tend to be less efficient than their vented counterparts. Vandersteen speakers certainly have bass enclosures which I believe are transmission lines. This is basically a vented design. There are excellent designs of either type and I wouldn't rule out any speaker simply based on its enclosure design.
I've never seen a sweep test of a sealed design that didn't have a hump in the upper bass (around 100 Hz). Yes, the rolloff is usually 12 dB/octave below that, but with an open baffle design, the rolloff is only 6 dB/octave. The rolloff of the bass doesn't determine quality, in and of itself.
Can we glean from your post that all acoustic suspension loudspeakers, or all at least for which you have seen a frequency sweep, start rolling off at or around 100 hz?
And would be 12 db down at 50 hz?