The Difference Between Sealed & Ported Subs
When it comes to subwoofers, the big question is whether to go sealed or ported - and the choice makes a bigger difference than you might imagine.
But is there a third way? We’ll explore that a little later on.
Ported Subwoofers = Big Deep Bass
First, let’s look at the ported subwoofer (or bass reflex design). This includes one or more vents that let air move in and out of the enclosure. This clever bit of engineering helps boost efficiency, delivering bigger, deeper, and more effortless bass output. The sound tends to be more powerful and room-filling - the kind that adds real low-down impact to movie soundtracks and gaming effects. When a ported sub hits, you feel it as much as you hear it.
Of course, that extra punch can come at the cost of precision. Ported subs can sometimes sound a little loose or boomy if not perfectly matched to the room, and they’re usually larger than sealed models. But if you love your bass big and cinematic, a well-designed ported subwoofer can bring genuine excitement and scale to your system. In short, sealed is all about accuracy and control, while ported is all about power and presence - it just depends on what kind of experience you’re chasing.
Sealed Subwoofers = Refined Clean Bass
By contrast, a sealed subwoofer, sometimes called an acoustic suspension design, also referred to, as infinite baffle. It uses a completely airtight box that keeps the bass controlled and nice and tight. The result is fast, accurate low-end that starts and stops exactly when it should, giving you that clean, articulate bass that feels natural rather than overblown. It’s the kind of sound that really shines with music, where timing and detail matter.
A sealed design also tends to be smaller and easier to position in most rooms, making it a great fit for compact spaces or setups where you want precision without drawing too much attention to the sub itself. The trade-off is efficiency - a sealed sub needs a bit more amplifier power to produce the same output as its ported counterpart, but in return, you get bass that integrates seamlessly with the rest of your system and never feels exaggerated.
What Is A Passive Radiator?
But what if there was a third way which was even better? Adding a passive radiator to a subwoofer is an elegant way to extend low-frequency performance without resorting to a large, ported enclosure. A passive radiator works much like a tuned port, but instead of relying on air moving through a tube, it uses a secondary diaphragm that resonates sympathetically with the active driver. This design allows for deeper bass extension and greater efficiency while maintaining the sealed enclosure’s tight, controlled character. The absence of a port also eliminates the turbulence, chuffing noise, and phase issues that can occur with traditional vented designs, leading to a cleaner, more articulate low end.
REL Subwoofers
Designers like John Hunter of REL Acoustics have long championed this approach for its ability to combine the speed and precision of a sealed system with the added weight and depth of a ported one.
In practice, a well-engineered passive radiator setup can make a compact subwoofer sound as though it’s playing in a much larger enclosure, delivering bass that’s full and powerful yet seamlessly integrated with the main speakers. It’s a solution that balances musicality with scale - ideal for listeners who want both finesse and physical impact from their low frequencies.
If you are shopping for a subwoofer let us help you pick the one, that’s right for you, your room and your system. Contact us to find out more.