Sealed vs Vented vs Bandpass: Which Enclosure is Right?

Choosing the right enclosure type is the most important decision in subwoofer design. Each has distinct acoustic characteristics that serve different goals.

Sealed

A sealed enclosure is the simplest: an airtight box with just the driver. The air inside acts as a spring, raising the system's resonant frequency.

Best for: Tight, accurate bass. Music listening, home theater, SQ competitions.

Trade-offs: Lower efficiency means you need more power for the same SPL. The roll-off below resonance is gentle (12dB/octave), which pairs well with room gain in car installs.

Vented (Ported)

A vented enclosure adds a tuned port (a tube or slot) that resonates at a specific frequency. Below tuning, the port "takes over" from the driver, extending bass response.

Best for: Higher SPL, deeper extension without massive power. Daily drivers, SPL competitions, music with deep bass content.

Trade-offs: Larger box volume, more complex construction with port routing. Below the tuning frequency, the driver is essentially unloaded — excursion spikes and distortion increases. A subsonic filter is recommended.

4th-Order Bandpass

A bandpass enclosure puts the driver between two chambers: a sealed rear chamber and a vented front chamber. Sound only exits through the port, creating a natural bandpass filter.

Best for: Maximum output in a narrow frequency band. SPL competitions, dedicated subwoofer duty where tight bandwidth is acceptable.

Trade-offs: Narrower bandwidth, more complex design with two chambers and an internal divider. Harder to build and tune. Changes in dimensions affect both chambers, making optimization critical.

How to choose

Use RokketBox's simulator to model all three with your driver. Compare the frequency response, group delay, and excursion curves side by side. The optimizer can then find the best dimensions for your chosen type.

There's no universally "best" enclosure — only the best one for your driver, your goals, and your available space.