Bica,
You are correct, the Timepiece 2.1, Continuum A.D. MKII and the Continuum 2.5 are all fundamentally bass-reflex designs. The key word is "hybrid." Although the underlying method for tuning is reflex loading, all three of those models also employ a system of internal chambering that loads the back-wave of the woofer in such a manner as to dampen and disperse the internal standing waves that normal reflex enclosures suffer from.
In most reflex designs, this back-wave energy "bounces around" (actually, it's much more complex than that but...) and creates pressure nodes that push on the woofer and force it to move. Once this occurs, the woofer has now become a "signal generator," transmitting that energy out into the listening area. These standing wave "resonances" are typically not distributed evenly across the low frequency band of the woofer, but are "bunched up" at a few select frequencies. This selective bunching up (resonances) can (and almost always does) produce signals that are much larger in magnitude (louder) than the original back-wave energy that excited them in the first place. They are usually narrow in bandwidth as well and cause peaks and/or dips in the frequency response of the system, depending on if they are in-phase, 180 degrees out of phase or somewhere in between... that of the original signal being produced by the woofer.
As bad as that may seem, peaks and dips in the frequency response are fairly well tolerated by human hearing. What really makes them bad is that they exit the system delayed in time from the original excitation signal (i.e., the music signal that we want). On top of that, they have a long decay time. Think of a bell being struck and how long it will ring before the sound completely fades away. The two of these added together makes the effect really bad and is one of the major sources of that "boxy" sound we all hate. The effect of these resonances can be easily seen in a standard "waterfall plot" commonly used in acoustical engineering. In such a plot, the resonances look like very "peaky" mountain ridges extending down (later in time) and perpendicular to the main ridge of the direct (original) signal - very ugly.
Sealed enclosures have the advantage of being able to use sufficient "stuffing" to eliminate these resonances, but if one were to do the same in a reflex design, that same amount of stuffing would dampen (kill) the box tuning resonance that we use to extend low frequency bandwidth. That's why many audiophiles prefer the sound of a sealed enclosure - they sound natural, not boxy, but to get the deep bass of an equivalent reflex design they would have to be very large in comparison.
Personally, I have always hated the sound of reflex enclosures for the very reasons outlined above. But from a marketing perspective, most folks don't like huge boxes - and I don't blame them. Even though our designs are not small by most standards, they are much smaller than they otherwise would be if they were sealed enclosures. We wanted to offer the extension of a reflex design without incurring the negative side effects, so in order to do so, we developed the "transmission-line like" internal chambering used in our designs. Based on the response of most listeners, I believe we have been successful.
I hope this helps.
-Bob
