R56 Mini Cooper S Up-Grade


Keith called my shop on Monday afternoon wanting a quick boost to the sound system in his wife’s Mini Cooper S. The car was fitted as standard with Mini’s Boost Audio system, which unfortunately is pretty poor-what the “Boost” refers to is anyone’s guess!

They’d had the car for just a week and weren’t keen on changing the styling of the dashboard or filling the boot with subs and amps. Sound quality and expandability were key for Keith so we set about designing a system:

Initially Keith was going to just amp the standard speakers and fit a sub. This all changed once we discussed what I was fitting in my Cooper S, the sublime Dynaudio MD102’s and MW162’s running actively, and I was asked what would be next down the list in terms of price when compared to the Dynaudio. The DBAudio Trex 5.2c were the natural choice, they feature Silk Domed Ring Radiator Tweeters (with phase plugs) a high quality cross-over and Kevlar coned midbass using a cast basket, for improved thermal power handling and reduced basket resonance, along with Voice Coil venting amongst others. They are a truly revealing speaker set-a previous customer only noticed the difference in symbal crashes between Left and Right channels on a Michael Jackson track after fitting these speakers in his car-he’d been listening to the track for 20yrs!

For an amplifier Keith couldn’t resist the Alpine PDX4.150. This is David and Goliath combined into one tasteful and compact amplifier-David is it’s compact size, Goliath it’s massive 4x 150WRMS power output. These little monsters were designed with Sound Quality (SQ) in mind and their “Class D” design makes them incredibly efficient and in turn means they generate little so can be stowed away in cubby holes or under false floors-ideal for this install. Two of the channels are driving the Trex 5.2c and the others driving the stock 6x9s-for the time being Keith’s keen to upgrade the rear drivers too!

Subwoofer wise there was only 1 choice-the Inphase USW10. These compact self amplified subwoofers will fit anywhere and have a surprisingly high output, the separate bass remote allows them to easily be adjusted from the front of the car-just what you need with a factory stereo and no sub-out!

So here are some pics from the install-we built a false floor in the boot of the Mini to house the amp and the subwoofer. The mids needed custom brackets fabricating to mount them to the front doors and the tweeters were temporally mounted on the dash-Keith is purchasing some original BMW “A” posts with tweeter mountings built in we’ll add pictures when we do that.

 BMW Mini Trex 002

Door Card removed for fiiting of Trex5.2c Midbass

BMW Mini Trex 005

New DbAudio Trex5.2c fitted on custom MDF baffle

BMW Mini Trex 006

PDX4.150 and USW10 in location, false floor to be added to cover the units.

BMW Mini Trex 007

False Floor installed, 8cm of depth lost from the boot-but you’d have to really know a Mini boot to know!

Equipment used:

DBAudio Trex5.2c

Alpine PDX4.150

Inphase USW10


Amp kit

Speaker Cable


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