CACar Audio Guide UK

UK car audio comparison

Best In Phase Car Subwoofers
in 2026.

A practical comparison of car subwoofers using enclosure type, power, dimensions and the installation space they need.

Prices and stock should be checked on the retailer page before purchase.

Our approach. We compare the specifications shown on the retailer product pages and explain who each model suits. This is not a hands-on test.

Our pick

In Phase XT-10 Kevlar Cone 2 Ohm Dual Voice Coil 1200W Peak Power Subwoofer

A bass subwoofer choice for adding more weight to the system.

Check price

Full specifications

Our picks compared

This table includes every verified specification available for the products in this roundup. Check the retailer page for the latest price, stock and fitment details.

ProductPriceAvailabilityBrandModelWarrantyProduct TypeSubwoofer DesignSizeListed PowerTypeFeatureShipping WeightFull specifications
In Phase XT-10 Kevlar Cone 2 Ohm Dual Voice Coil 1200W Peak Power Subwoofer£69.99In stockIn PhaseXT-102 Year WarrantyCar SubwoofersNot listedNot listed1200WNot listedDual Voice Coil5 kg
  • Power Detail: 2 Ohm
  • Size Detail: 10 inch
In Phase XT-6 800W Peak Power 6.5" Kevlar Cone 2 Ohm Dual Voice Coil Subwoofer£79.99In stockIn PhaseXT-62 Year WarrantyCar SubwoofersNot listed6.5 inch800WNot listedDual Voice Coil5 kg
  • Power Detail: 2 Ohm
In Phase XT-10D2 Kevlar Cone 1Ω Dual Voice Coil 1200W Peak Power Subwoofer£89.99In stockIn PhaseXT-10D22 Year WarrantyCar SubwoofersNot listedNot listed1200WNot listedDual Voice Coil5 kg
  • Power Detail: 2 Ohm, 4 Ohm
  • Size Detail: 10 inch
In Phase USW300 300W Underseat Ultra Slim Compact Active Subwoofer System Die-Cast Aluminium£99.99In stockIn PhaseUSW3002 Year WarrantyCar SubwoofersActiveNot listed300WOEM Headunit Connection, Underseat SubwooferBuilt In Amplifier5 kg
  • Product Detail: 4 Ohm
  • Size Detail: Under Seat
In Phase XT-12D4 Kevlar Cone 2Ω Dual Voice Coil 1400W Peak Power Subwoofer£99.99In stockIn PhaseXT-12D42 Year WarrantyCar SubwoofersNot listedNot listed1400WNot listedDual Voice Coil5 kg
  • Power Detail: 2 Ohm
  • Size Detail: 12 inch
In Phase XT-12D2 Kevlar Cone 1Ω Dual Voice Coil 1400W Peak Power Subwoofer£99.99In stockIn PhaseXT12-D22 Year WarrantyCar SubwoofersNot listedNot listed1400WNot listedDual Voice Coil5 kg
  • Power Detail: 1 Ohm
  • Size Detail: 12 inch

Product notes

What each pick is best at

In Phase XT-10 Kevlar Cone 2 Ohm Dual Voice Coil 1200W Peak Power Subwoofer

Best overall bass upgrade

In Phase XT-10 Kevlar Cone 2 Ohm Dual Voice Coil 1200W Peak Power Subwoofer

A bass subwoofer choice for adding more weight to the system.

What we don't like

  • Unlike some alternatives, the listing does not show a comparable design figure, so matching it to the rest of the system takes more checking.
  • The enclosure and underseat or boot dimensions still need checking, even where the product is described as compact.
Price£69.99
AvailabilityIn stock
Listed Power1200W
ModelXT-10
Warranty2 Year Warranty
BrandIn Phase
FeatureDual Voice Coil
Power Detail2 Ohm
Product TypeCar Subwoofers
Shipping Weight5 kg
Size Detail10 inch
Check CarAudioCentre.co.uk
In Phase XT-6 800W Peak Power 6.5" Kevlar Cone 2 Ohm Dual Voice Coil Subwoofer

Best for compact installations

In Phase XT-6 800W Peak Power 6.5" Kevlar Cone 2 Ohm Dual Voice Coil Subwoofer

A 6.5-inch bass subwoofer choice for adding more weight to the system.

What we don't like

  • It is £10.00 above the cheapest pick, so the higher price depends on whether the distinct 6.5-inch size suits the installation.
  • The enclosure and underseat or boot dimensions still need checking, even where the product is described as compact.
Price£79.99
AvailabilityIn stock
Listed Power800W
ModelXT-6
Size6.5 inch
Warranty2 Year Warranty
BrandIn Phase
FeatureDual Voice Coil
Power Detail2 Ohm
Product TypeCar Subwoofers
Shipping Weight5 kg
Check CarAudioCentre.co.uk
In Phase XT-10D2 Kevlar Cone 1Ω Dual Voice Coil 1200W Peak Power Subwoofer

Best for boot-based systems

In Phase XT-10D2 Kevlar Cone 1Ω Dual Voice Coil 1200W Peak Power Subwoofer

A bass subwoofer choice for adding more weight to the system.

What we don't like

  • It is £20.00 above the cheapest pick without a clearly unique listed specification to explain the difference.
  • The enclosure and underseat or boot dimensions still need checking, even where the product is described as compact.
Price£89.99
AvailabilityIn stock
Listed Power1200W
ModelXT-10D2
Warranty2 Year Warranty
BrandIn Phase
FeatureDual Voice Coil
Power Detail2 Ohm, 4 Ohm
Product TypeCar Subwoofers
Shipping Weight5 kg
Size Detail10 inch
Check CarAudioCentre.co.uk
In Phase USW300 300W Underseat Ultra Slim Compact Active Subwoofer System Die-Cast Aluminium

Best for factory stereos

In Phase USW300 300W Underseat Ultra Slim Compact Active Subwoofer System Die-Cast Aluminium

A active subwoofer choice for adding more weight to the system.

What we don't like

  • It is £30.00 above the cheapest pick, so the higher price depends on whether the distinct Active design suits the installation.
  • The enclosure and underseat or boot dimensions still need checking, even where the product is described as compact.
Price£99.99
AvailabilityIn stock
Listed Power300W
ModelUSW300
Subwoofer DesignActive
Warranty2 Year Warranty
BrandIn Phase
FeatureBuilt In Amplifier
Product Detail4 Ohm
Product TypeCar Subwoofers
Shipping Weight5 kg
Size DetailUnder Seat
TypeOEM Headunit Connection, Underseat Subwoofer
Check CarAudioCentre.co.uk
In Phase XT-12D4 Kevlar Cone 2Ω Dual Voice Coil 1400W Peak Power Subwoofer

Best for stronger low end

In Phase XT-12D4 Kevlar Cone 2Ω Dual Voice Coil 1400W Peak Power Subwoofer

A bass subwoofer choice for adding more weight to the system.

What we don't like

  • It is £30.00 above the cheapest pick without a clearly unique listed specification to explain the difference.
  • The enclosure and underseat or boot dimensions still need checking, even where the product is described as compact.
Price£99.99
AvailabilityIn stock
Listed Power1400W
ModelXT-12D4
Warranty2 Year Warranty
BrandIn Phase
FeatureDual Voice Coil
Power Detail2 Ohm
Product TypeCar Subwoofers
Shipping Weight5 kg
Size Detail12 inch
Check CarAudioCentre.co.uk
In Phase XT-12D2 Kevlar Cone 1Ω Dual Voice Coil 1400W Peak Power Subwoofer

Best for flexible installation

In Phase XT-12D2 Kevlar Cone 1Ω Dual Voice Coil 1400W Peak Power Subwoofer

A bass subwoofer choice for adding more weight to the system.

What we don't like

  • It is £30.00 above the cheapest pick without a clearly unique listed specification to explain the difference.
  • The enclosure and underseat or boot dimensions still need checking, even where the product is described as compact.
Price£99.99
AvailabilityIn stock
Listed Power1400W
ModelXT12-D2
Warranty2 Year Warranty
BrandIn Phase
FeatureDual Voice Coil
Power Detail1 Ohm
Product TypeCar Subwoofers
Shipping Weight5 kg
Size Detail12 inch
Check CarAudioCentre.co.uk

Buying guide

What to check before ordering

Start with the space available, then compare RMS power, enclosure type and input options. A factory stereo may need high-level inputs or a line-out converter, while a passive subwoofer needs a separate amplifier.

Use the model number as the final reference. Retailer images and prices can change, and vehicle fitment should be confirmed for the exact make, model and year.