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In Phase Car Audio USW300 - 300W Underseat Compact SubwooferUSW300
£149.99 Save £50.00  was:£199.99
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Fit it Yourself?

Everything you need to fit it yourself at home

Only £30.00 

With Steering Wheel Control
Only £50.00 

5 Stars (57)

In Phase Car Audio USW300 - 300W Underseat Compact Subwoofer

£149.99 Save £50.00 (25%)  was:£199.99
5 Stars
57 Review(s) / write a review
Quickfind Code - 42186
Quick Summary:

Made from Diecast Aluminium fits snuggly under the seat of any car or in two seaters even behind the seats. Can be mounted inside the boot area also. Has complete control allowing for volume and phase adjustment by rotary hardwired.

Condition: New

Save £50.00 (25%)
rrp: £199.99
Pre Order: stock expected on: 31 March 2022
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Key Features

300W Underseat Compact Subwoofer - In Phase Car Audio USW300

The key thing about the In Phase USW 300 is the performance, the little active woofer really packs a punch, the bass response is amazing, you really do get SUB Bass from it. Its extremely responsive so the music has a completely different sound once added to the car. Many people think about changing speakers in you car, my advice is just add the USW 300 and you will think you have new life in your car! Enjoy its an awesome product.
This underseat subwoofer comes with it's own wiring and amplifier. Please do not use any other kit. 

Download image of In Phase Car Audio USW300 Click here for Image of In Phase Car Audio USW300
Technical Specification
  • 5" x 8" Aluminium Speaker
  • 130w RMS
  • 300w Max Power
  • Die Cast Aluminium construction
  • Variable Subwoofer crossover 40-150hz
  • Speaker Frequency range 40-150hz
  • Bass Boost 26db Gain @ 42Hz
  • Bass Boost Frequency
  • Wired Remote Control
  • High Level speaker input
  • Line input
  • Max Power consumption 10Amp
  • LED Power Indicator
  • Super Compact design
  • W 280mm x H 200mm x D 75mm
  • Weight 3.7KG
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Customer reviews

Sound not great
ANTHONYMUSKETT on 04/01/2022 2 star rating

I bought this sub as it had good reviews and had double the power of my current under seat sub. I was not impressed with the sub at all it is not very loud and when you can hear it it is distorted. While driving it might as well not be there at all. Very disappointing as I have another mode of in-phase in my van and that is brilliant

Benjamin W on 26/11/2021 5 star rating

This is a fantastic choice for a small car too (Ford Fiesta) - I've not tried the Kenwood competitor (which was my original plan) but knowing what I do about audio equipment and subs/amps performing best with plenty of headroom (and reading a number of reviews of the Kenwood dying, presumably from pushing the smaller amp too hard), I'm very glad I upgraded. The USW300 is plenty, but I also wouldn't want much less. I've had a full 600w monoblock driven 12inch ported Kenwood setup in the past (in a different car), and the little InPhase unit gives me about 90-95% of the joy of that experience but with literally zero intrusion in my storage space. Very happy with the little fella

Plenty of bass for the tiny package
TOBY on 19/11/2021 5 star rating

Tonnes of bass from such a small package, very easy to install with plenty of extra wire than I needed. Very satisfied with the bass even in my MR2s small cabin.

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Questions/Answers About This Product
  • Question: 18 January 2022
    Car: VW Transporter - 2005 >

    I am looking for an active install in the space under one of the front seats in my T5. Is this sub supplied with a bracket or kit to secure it in place? TIA


    It does come with basic installation equipment but not it might be worth giving us a call to confirm.

    Found Useful? Yes 

  • Question: 01 January 2022
    Car: Ford Transit - 2005 >

    Please can I have a cost for fitting to a transit custom (2016 ) head unit is original. Also available fitting dates please ( Saturdays would be perfect if possible ) ?
    I think Nottingham is nearest


    Please contact the store directly-

    Found Useful? Yes 

  • Question: 18 November 2021
    Car: VW Golf - 2003 > MK5

    Will this fit into a 2011 sirocco with standard head unit, will it need additional connectors if so what would I need extra?


    This sub comes with all wiring needed. Regards to fitting, it should fit in your vehicle yes however, i would advise measuring the space you have and comparing the dimensions to the subwoofer to make sure.

    Found Useful? Yes 

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Fitting Services

Need help with Installation?

Here at CarAudioCentre we offer a professional and reputable fitting service in all our stores. For all fitting enquiries and bookings please visit or call one of our nationwide stores. Our fitters can install your new car stereo, DAB radio, audio visual, speakers, subwoofers or amplifier. We can also help to connect your iPod or MP3 player to you existing audio unit and can offer the best advice on the right in-car entertainment for your vehicle, to further this more we also offer a total 100% custom installation service for demo and show vehicles. So if you have an idea come on in and run it past us, the possibilities are endless and we are never too busy for an enthusiastic chat about our favourite subject.

Please note:

"That our two year warranty on products is only applicable to purchases made directly from us and that have been fitted in one of our stores."

Our Stores:

542 546 Mansfield Road, Sherwood NG5 2FR
Tel: 0115 9624 986
743-745 Eastern Ave, Newbury Park, London, IG2 7RT
Tel: 0208 599 2368
835 Garratt Lane, Tooting, London, SW17 0PG
Tel: 0208 971 9181