In Phase USW300 Underseat Subwoofer | Car Subwoofer with Built in Amplifier

I was a little sceptical before ordering and was considering building something to go under the floor in my SLK. However I purchased one to try and was not disappointed. I fitted under the floor in the passenger side footwell on an SLK, some models have an amp fitted there. At the same time I replaced the headunit with a powered android type with CarPlay. Fitting was easy as the Android head had cables to connect to and a sub output. The remote was remotes to the side of the centre console, convenient for adjustments should I need to. Build quality is good, sound quality is excellent for a compact sub of its size it compliments the rest of the speaker system. It was actually worth spending the money on this product, if you can’t get a big box in anywhere this is the ideal choice and with the remote just adds to the functionality, to be fair I’ve not had the need to alter it from the initial twiddling. I’ve written this after purchasing in August 2024, just in Dec 2025 now and still enjoying the sub!

+ Great Sound, Great Quality, Easy to Install, Fantastic Value. - No RCA Leads. This is a great little sub if you’re after a fuller sound for your car. I installed a set of component speakers into a Kangoo van and was disappointed with the bass, so I fitted this and it’s made a massive difference! It’s a substantial well built item and has all the sound controls on the remote instead of fiddly dials on the back of the unit which makes it great to tune while it’s situ without messing around accessing it again. It comes with all the leads you need to get it running via high level input, but you will need to but a phono lead if you want to connect it via low level RCA.

Bought for my little peugeot 107 to add some bass to the pathetic little 4" speakers I have. This is a great little mini-sub, fits under the seat and was reasonably easy to fit. (Bit fiddly getting power from the engine bay and connecting the earth). Sound at normal volumes is actually pretty good, and fills out the bottom end of what the car speakers lack. For regular use it's not bad at all for the price. Now it must be said it does start to distort a little at louder volumes and is not your window shaking drum 'n bass sort of sub, but with a bit of tweaking from the controls and not raising the gain or bass-boost to silly levels you do get a good fill in low-end sound. So yeah, I'd recommend it if you're on a budget or got a small car.

This little sun-woofer is just excellent for what I need it for , car came with very standard sound system with no bass at all in the speakers , friend told me about this active sub woofer so I got one , easy to instal if your familiar with cars and electrics , it’s perfect for what I need it for .. I couldn’t put mine under the seat so wired it to the boot area and it still works perfectly.. bass is local and loud enough for my use

Really good bit of kit, made a huge difference to the bass! Well worth 100 bucks

What an incredible bit of kit! I’ve installed it under the drivers seat of my 2009 Smart Fortwo (wont fit under the passenger seat). It has transformed the sound quality in the car. Being a small car it only has two speakers, i upgraded these to some decent three ways but it still lacked some depth. This has sorted that out. I installed it using the High power input (speaker feed). It’ll take some fettling to get things sounding perfect but thats a personal preference. I would 100% recommend this. Not sure how effective it would be in a much bigger car but definitely does what it should do.

Great sound, full kit included for install, you might want to watch a few YouTube videos on how to install. Fits under the passenger seat so perfect size, 10/10 and glad I went with the British design over my usual choice of Pioneer for anything sound

These under seat powered subs are a really good solution for those of us who don't want to do a full installation. Some of them can go for silly money and being the cheap northerner that I am, I chose to take a punt on the In Phase. Installation instructions are straightforward and I chose to tap into the rear speakers using some wire tapping clips, rather than using the RCA option. I put it in behind the driver's seat. Even though its a proper coupe, i reckon i could have got away with putting it in the spare wheel well and still getting a good boost. I've found I need to use very little gain, no bass boost and I have the LPF set quite low and it gives a lovely boost to the standard stereo and rounds off the sound nicely. Testing with some well rounded tracks has yielded great results, but some tracks like Feuer Frei and Before I Forget just have too much distorted bass and it's a little bit much for my ears. Overall, for £99 for an amplified sub and all the cables required and giving the sound quality it does, I'd say its a good deal!

Kleiner als der Pioneer 130, den ich vorher 6 Jahre im Auto hatte. Passt damit sehr gut unter den Fahrersitz im PT Cruiser, der 130 wäre schon enger geworden (dpasste sehr gut unter den Beifahrersitz im W201). Der Bumms tatsächlich größer,-und jetzt einstellbar. Da die Vorlieben je nach Musik unterschiedlich sind, finde ich die Fernbedienung nun immens wichtig. Alle Parameter lassen sich sofort anpassen. Wie konnte ich vorher ohne auskommen? Verarbeitung wirkt sehr wertig, ein schweres Teil mit allem Zubehör bis auf eine Chinch-Leitung und Y-Adapter, wenn nur ein Ausgang. Alle Kabellängen mehr als ausreichend. Das blaue kleine Birnchen an der Fernbedienung zeigt einem auch den On-Status,- nach dem Abstellen des Fahrzeuges sollte sie ausgehen, sonst hätte man bald ein Startproblem. Alles in allem hat sich mein Mut gelohnt, ein guten Subwoofer mit einem vielseitigeren zu ersetzen. Über die Haltbarkeit kann ich beim USW 300 noch nichts sagen,-der Pioneer war nach 6 Jahren noch tadellos.

Fonctionne très bien pour le prix

Bought as "Used - like new", condition was basicly brand new, no marks on cables or on the subwoofer. Installation took roughly 3 hours, would've been a lot faster if I had known how to get the power cable from the battery throught cabin firewall to the subwoofer. Installed on 2016 Seat Alhambra. Sound quality = excellent. Gives nice deep bass to the original car stereo and speakers. Would definetly buy again. A big plus for this woofer is the wiring kit, it includes everything you need for the installation.

Super kit très puissant malgré sa petite taille. En tout cas ça rentre parfaitement sous le siège. J'ai été surpris par tout le contenu malgré le petit prix, vous avez absolument tous les fils pour l'installer ( sauf les RCA si vous voulez l'installer avec la sortie sub du poste. Il ne reste plus qu'à voir la durée dans le temps

Bei meinem Wohnmobil (VW Crafter) ist der Sound bisher, trotz neuen Türlautsprechern mehr schlecht als recht. Der Subwoofer den ich im Sitzkasten des Beifahrersitz montiert habe, verbessert den Klang um welten. Es kommt mit ein paar Anpassungen mit Hilfe der Reglereinstellungen des Subwoofer und am Radiogerät selbst zu einem deutlich besseren Klangbild, und zwar nicht nur im Bassbereich. Man hat den Eindruck das auch aus den anderen Lautsprechern ein besserer Sound raus kommt, was natürlich nur eine Empfindung ist. Für Bassjunkies mag dies vielleicht nicht ausreichend sein, für mich ist der Einbau des Subwoofer aber ein deutliche Verbesserung. Der Anschluß geht auch recht schnell von der Hand, gut ist natürlich wenn Stromversorgung in der Nähe ist und die Steuerleitung und ein Cinchkabel vom Radio in der Nähe griffbereit ist, was bei mir der Fall war, so hat der Einbau ein knappe Stunde gedauert. Ein sehr gutes Preis-Leistungsverhältnis, wie ich finde.