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In Phase Car Audio USW300 - 300W Underseat Compact SubwooferUSW300
£99.99 Save £100.00  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 (64)

In Phase Car Audio USW300 - 300W Underseat Compact Subwoofer

£99.99 Save £100.00 (50%)  was:£199.99
5 Stars
64 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 £100.00 (50%)
rrp: £199.99
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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

Phase USW300 .
GUISEPPE on 29/06/2022 5 star rating

Fits perfectly in the designated cradle in the footwell of my mercedes slk great sound only need around 30% power boom!

Nice item
ROY on 21/06/2022 5 star rating

Great value and Really easy to fit placed my sub in the boot got a really nice bass now, would recommend for a enhancing clean bass but if you want a mega deep bass it’s not for you.

Good for the price
Michael on 10/06/2022 4 star rating

I have purchased this to fit it the boot of my mazda 3 and really does a good job except for few songs where some type of bass is reproduced extremely low. Not blown away but there is a bass improvement better that the speakers alone can do. I still believe that the ideal place for this subwoofer is under passenger seat not for the boot, a quite lowder and would have been very good for boot.

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Questions/Answers About This Product
  • Question: 29 June 2022
    Car: Ford

    Just bought one of these from yourselves.How much power do they draw when the stereo is switched off, as the Subwoofer is always on? It’s connected straight through to the battery as instructions.


    Wire the REM up to an ignition feed, that will tell the amp when and when not to power up

    Found Useful? Yes 

  • Question: 26 May 2022
    Car: Vauxhall Zafira - 2007>

    do you do installs of the In Phase Car Audio USW300 - 300W Underseat Compact Subwoofer - if so can I have a quote please and how long I would need to leave the car?


    Our stores can provide the fitting service for you. Sadly, you have come through to the mail order centre, so we cannot give you a price for that service. Please contact them on the below emails for more assistance.

    Car Audio Centre Nottingham
    120-122 Alfreton Road
    NG7 3NR
    0115 845 3462

    Car Audio Centre Ilford
    743-745 Eastern Ave,
    Newbury Park,
    IG2 7RS
    0208 599 2368

    Car Audio Centre Tooting
    835 Garratt Lane,
    SW17 0PG
    0208 971 9181

    Found Useful? Yes 

  • Question: 08 May 2022
    Car: Vauxhall Astra - 2010>

    I bought the inphase 300w underneath sub woofer for my car. Do I need anything else to connect to standard stereo?


    No, you just need to run the power cable to the battery and tap into the OEM speaker cable for audio signal

    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:

120 - 122 Alfreton Road, Nottingham, Nottinghamshire, NG7 3NR
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