Insights
How the bass breathes.
The way the cabinet manages the air behind the cone changes the bass more than you might imagine.
The sealed box: bass kept lean
The sealed cabinet holds the air behind the cone, and that air acts as a spring: it calls the movement back with precision. The result is a bass that is lean, controlled, clean on sudden transients.
It reaches a little less deep, but it does so gently and keeps boom at bay. It is the choice of restraint.
Bass reflex: more bass from the same air
The bass reflex opens a tuned port that recovers the air moved by the rear of the cone and returns it in phase, reinforcing the lowest notes. From the same cabinet comes more extension and more efficiency.
It is the most common solution, but it must be tuned with care: done poorly, the bass swells. Done well, it breathes.
The passive radiator: reflex without a port
The passive radiator — a cone with no motor, moved only by the air within — does the same work as the port, but without a tube. It is tuned by a mass rather than by the length of a channel.
It brings the same reinforcement of the bass in a more compact form and without the air noise a port can make: acoustic elegance, where space matters.