8 Inch Car Subwoofers (20cm)

Buying 8 inch car subwoofers in 2026: the complete guide

8 inch car subwoofers remain one of the most popular upgrades on British roads. A 20cm chassis fits a huge number of factory apertures, so you get a genuine improvement without cutting metal. Bass Junkies lists 110 products in this size, which is enough choice to be confusing. This guide explains how to pick correctly first time.

Check the size before you order

A 8 inch driver needs both a cut out diameter and a mounting depth to clear. Measure the usable boot or underseat space, then check the enclosure volume the manufacturer specifies. Sealed boxes need less air than ported ones and give tighter, more accurate bass, while ported designs go louder for the same power. If space is genuinely limited, look at shallow mount and underseat active models rather than forcing a standard driver into a box that is too small.

Driver, loaded box or complete package

• Raw drivers. Best value per watt and the right choice if you are building or already own a correctly sized enclosure.
• Loaded enclosures. A driver pre fitted into a sealed or ported box, tuned by the manufacturer, so performance is predictable out of the carton.
• Amplified bass boxes. Sub, box and amplifier in one unit, the fastest route to bass and ideal where boot space and wiring time are limited.
• Complete bass packages. Sub, enclosure, amplifier and wiring kit supplied together and matched, which removes the impedance guesswork entirely.

Power handling and amplifier matching

• Read RMS, not peak. RMS is continuous power and the only figure worth matching. Peak numbers are marketing.
• Match amplifier RMS to speaker RMS. Aim within roughly twenty per cent either way, then set gains by ear at moderate volume.
• Watch impedance. Dual voice coil subwoofers can be wired to different final loads, so check what your amplifier is stable at before ordering.
• Sensitivity matters on low power. Running straight from a factory head unit, a higher sensitivity rating will sound noticeably louder than a higher wattage rating.

Brand quality at a glance

• Kicker. American built with high excursion motors, a favourite for bass heavy installs.
• Alpine. Reliable all rounders with well judged power handling and excellent vehicle specific ranges.
• Vibe. UK designed, with shallow mount and vehicle specific options that solve awkward fitment.
• Phoenix Gold. Serious power handling and build quality for amplified systems.
• Focal. French engineered components with flax and polyglass cones, the benchmark for sound quality upgrades.
• Pioneer. Britain's best selling car speaker brand, with huge choice at sensible money and consistent fitment.
• JL Audio. Premium US engineering with class leading control and enclosure guidance.
• Caliber. Budget friendly European brand for straightforward replacements.

Compatibility and fitting

If you are upgrading the head unit at the same time, these four parts turn a difficult job into a tidy one. We stock all of them alongside the speakers and subwoofers.

• Fascia adapter. Fills the factory aperture so a single or double DIN unit sits flush. Browse the car stereo fitting accessories range.
• ISO harness. Plugs into the factory loom so no original wiring is cut, which protects resale value and makes reversal simple.
• Steering wheel control adapter. Retains volume, track and phone buttons on the wheel. See steering wheel control interfaces.
• Aerial adapter. Converts the factory antenna plug to a standard DIN connector and supplies phantom power where the vehicle needs it.

Fitting depth, sealing and getting the best from the install

Bass is lost through leaks and rattles long before it is lost through the driver. Seal the enclosure, brace loose boot trim and use a correctly rated wiring kit so the amplifier is not starved of current. Set the low pass filter around eighty hertz, engage the subsonic filter on ported boxes, and match phase with the front stage.

What to spend in 2026

• Under 100 pounds. Entry level drivers and compact enclosures. A clear improvement over factory, best paired with a modest amplifier.
• 100 to 300 pounds. The value sweet spot. Solid motor structures, better cone control and enclosures worth keeping long term.
• 300 pounds and up. Competition grade drivers, high excursion designs and premium loaded boxes for demanding builds.

Why buy from Bass Junkies

We have been supplying and fitting car audio since 1995, so the advice you get comes from installs we have actually done. Everything is picked, checked and dispatched from our own Wolverhampton workshop. Call the team on 01902 863 005 and we will confirm fitment and impedance for your exact vehicle, then point you at the amp wiring kits you need.