Subwoofer Buying Guide: Sizes, Sealed vs Ported, and Powering It Right

Buying a subwoofer is one of those purchases where the spec sheet tells you less than you'd hope. Two subs with identical wattage ratings can sound completely different depending on their size, the box they sit in, and the amplifier driving them. This guide walks through the decisions that actually matter, in the order you should make them. If you'd rather skip the homework, we design enclosures and tune systems in-house at our shop in Chilliwack, and we ship gear Canada-wide.

What size subwoofer should you get?

There is no single best size. Each diameter trades accuracy against output, and the right answer depends on the music you listen to and the space you have.

• 8-inch: The tightest and quickest of the bunch. An 8 won't shake your mirrors, but it adds clean low-end definition that factory speakers can't reach. A good fit for small cabins, jazz, rock, and anyone who wants bass they feel slightly rather than hear from the next block.
• 10-inch: The all-rounder. Tens respond quickly enough for fast double-kick and busy basslines while still producing real impact. If you're unsure, a 10 in a well-built box is rarely the wrong call.
• 12-inch: The most popular size for a reason. A 12 moves enough air for hip-hop, EDM, and anything with sustained sub-bass, while remaining controlled enough for everyday listening. Most single-sub builds we do land here.
• 15-inch: Output first, finesse second. Fifteens excel at low-frequency volume and are the usual choice when the goal is SPL — sheer loudness — rather than note-for-note accuracy. They need serious enclosure volume and serious power to do their job.

The honest summary: smaller subs favour speed and accuracy, larger subs favour output and depth. Browse our subwoofer collection to compare sizes and brands side by side.

Sealed vs ported: what the box actually does

The enclosure is not packaging — it is half the speaker. The same subwoofer in a sealed box and a ported box will behave like two different products.

Sealed enclosures

A sealed box traps a fixed volume of air behind the cone, which acts like a spring. The result is tight, accurate bass with a smooth roll-off into the lowest frequencies. Sealed boxes are smaller, more forgiving of minor design errors, and better at reproducing fast, complex bass. The trade-off is efficiency: a sealed sub needs more amplifier power to reach the same volume as a ported one.

Ported enclosures

A ported (vented) box uses a tuned port to reinforce output around a specific frequency. At and near that tuning frequency, a ported box can play noticeably louder than a sealed box with the same sub and the same power. The trade-offs are real, though: ported boxes are larger, the bass is generally less tight, and a port tuned to the wrong frequency — or built to the wrong dimensions — can sound boomy and one-note. Below the tuning frequency, the sub loses the air spring that controls it, so a proper subsonic filter matters.

Rule of thumb: sealed for accuracy and mixed-genre listening, ported for maximum output per watt with bass-heavy music. Neither is better; they are tuned for different goals. This is also where a custom box earns its keep — we design and build enclosures in-house in Chilliwack, matched to the specific driver and the space in your vehicle, rather than guessing with a generic prefab box.

Shallow-mount subs for trucks and tight spaces

If you drive a pickup or a car with no spare cargo room, shallow-mount subwoofers are built for you. They use a compressed motor structure and a shallower cone profile so the whole assembly fits behind or under a seat, in an enclosure a fraction of the usual depth. A shallow 10 or 12 won't match the raw excursion of a full-depth driver, but modern shallow designs produce genuinely satisfying bass — far beyond what any factory system delivers — without sacrificing your back seat. We build under-seat and behind-seat enclosures for trucks regularly, sized to the actual cab, not a catalogue average.

Matching amplifier power to RMS

Ignore peak or "max" wattage entirely — it is a marketing number. The figure that matters is RMS, the continuous power a sub is built to handle. The guidance that has held up for decades:

• Choose an amplifier whose RMS output, at the impedance you'll actually wire the sub to, is roughly equal to the sub's RMS rating. Somewhat above is fine; clean headroom is safer than a starved amp.
• Underpowering isn't automatically safe. An undersized amp pushed into clipping sends distorted signal that cooks voice coils faster than honest power ever will. More subs die from clipping than from too many watts.
• Impedance matters. A dual-voice-coil sub can be wired to different final impedances, and the amp's output changes accordingly. Match the wiring configuration to the amp's rated load before you buy either piece.

If you're pairing components, our amplifier collection lists RMS ratings at each impedance, and we're happy to confirm a match before you order.

Why true OFC power wire matters

An amplifier is only as strong as its power supply, and that supply runs through the wire from your battery. Cheap amp kits are usually copper-clad aluminum (CCA): aluminum strands with a thin copper coating. Aluminum has roughly 60 percent of copper's conductivity, so a CCA wire of a given gauge carries meaningfully less current than its label suggests — which means voltage drop under load, an amp that sags exactly when the bass hits hardest, and extra heat in the wire. True oxygen-free copper (OFC) wire delivers the full current the amp was designed around and stays flexible in cold weather, which matters in a Canadian winter. Sizing the gauge to the amp's current draw and the cable run length is part of any install we do; you can find properly rated cable in our OFC power wire sale.

Set the gain with test tones, not by ear

The gain knob on an amplifier is not a volume control — it matches the amp's input sensitivity to your head unit's output voltage. Set it by ear and you will almost always set it too high, because distortion at low frequencies is hard to hear until it has already damaged something. The proper method uses test tones: play a reference tone, bring the head unit to its maximum clean volume, then raise the gain until the amp reaches its target output — measured with a multimeter or, better, an oscilloscope that shows the exact point the waveform begins to clip. Done this way, the system plays at full output without sending distorted signal into the sub. It takes equipment and about twenty minutes; it is the difference between a system that lasts years and one that eats voice coils.

Getting it done in Chilliwack

Every piece above — enclosure design, amp matching, OFC wiring, oscilloscope gain-setting — is standard practice in our install bay at 45885 Alexander Ave. If you're local, book a subwoofer and amplifier installation and we'll handle the whole chain. If you're elsewhere in Canada, order the gear and call us before you buy; five minutes on the phone prevents most mismatches.