You mean acoustic suspension from the old days or just an airtight box with modern stuff? Or are you referring to some ported designs that with port plugs/dsp settings that can imitate certain sealed functions?
A dual opposed 6.5" "sub"? Seriously? For $1500 yet? Good grief. Why is such a small box desired? Hamstringing a sub doesn't mean it's more musical....good grief.
Been some interesting reviews of that one:
Award-winning subwoofer bends the laws of physics
www.whathifi.com
Can a small little subwoofer, the KC62 from KEF keep up with the big boys with an enclosure about the size of a basketball?
hometheaterhifi.com
Yes I do mean acoustic suspension from the old days (still current in designs like the KC62, or the Gallo TR1/TR3) - it uses a softer woofer surround - less resistance/less distortion - but still achieves the required suspension action through the compression of the air within the sealed Box/Cylinder...
Most of the woofers available today, are designed for ported designs - so they have much heavier suspension surrounds.
It does have constraints... if you consider max SPL output of 105db a constraint.
If the listener is a fan of the Harman Curve with +10db in the bass, and uses an average listening volume of 85db - then it isn't a constraint - you still have 20db of headroom
My own average listening level is around 75db... so this would be far from constraining !!
But tastes, and the ability to bear loud sounds, varies with the listener - some might seek max SPL's of 110db or more... - not me!
Also I strongly believe that many (most?) subwoofers sacrifice distortion for SPL's - they go low and loud, but they also have very high THD - which matters not at all for a home theatre LFE subwoofer, intended for explosions and earthquakes.... but if you want to get the tone of a double bass or Harp right, (bottom note fundamentals of 41Hz and 31Hz respectively) - then most of the "effects" focused subs are a bit of a "blunt tool".
there's a discussion of sealed vs ported on the SVS website:
Our most common question answered in a few simple steps – learn what’s right for your system and listening needs.
www.svsound.com
To quote: "A properly designed sealed subwoofer will typically exhibit less phase rotation, lower group delay, and reduced ringing in the time domain. Sealed cabinet subwoofers are generally more accurate in frequency response and better at rendering instrumentals in a convincing way. These characteristics make the sealed subwoofer a natural choice for critical music applications and are typically described by enthusiasts as sounding tighter and more articulate or musical, with less perceived overhang. "
Downside: "a sealed subwoofer will typically have considerably lower dynamic output limits than a ported subwoofer in the same family/price range. "
I'm a fan of the sealed genre.... - the SVS article goes into further detail on the advantages of the ported genre... they make both.
