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Buying a CD tuner for a car in the £200 band offers an excellent choice usually with iPod and steering wheel control/vehicle display compatibility. Most are Bluetooth-ready for hands-free phone calls or audio streaming and these add-ons involve extra wiring and possibly an interface box.
CD decks at this level are usually CD Text compatible and 24 bit playback is common, as is the use of hi-fi quality digital to analogue converter chipsets. All these units also offer excellent line-out facilities for adding external amplifiers with stereo outputs for front, rear and bass speakers. The most useful addition is a bass amplifier and boxed subwoofer.
Mobile phones with music streaming will usually play through the head unit with a Bluetooth adapter. The Apple iTouch phone, by the way, has music streaming compatibility with regular iPod interfaces. The additional Bluetooth box usually costs around £100 but often includes features such as the ability to see your address book on the set's display panel and voice-prompted dialling.
All these sets will play recordable and rewritable CDs and most of them cover the most popular music files, including standard MP3, WMA, and iPod-friendly AAC. Some will also play WAV files which, although they take up a lot of space on CD, have the benefit of being a lossless format with excellent sonic performance.
Some sets such as the Alpine offer an iPod adaptor lead as standard whereas most manufacturers charge extra. Luckily, even the priciest adaptors are not much more than £20. Some plug into a disc auto changer socket or into a USB port. Most sockets don't have a full USB specification which means PC-style data channels may be missing and the power ratings could be different.
While they can all play from memory dongles and most can handle micro-drives, not all of them are compatible with portable HDD hard disk drives, particularly if the first non-partitioned folder doesn't contain music files.
You can expect iPod adaptor leads to be compatible with the new Apple iTouch and iPhones audio output but even if the head unit is claimed to be compatible, but the real guarantee is to try it at your friendly dealer's shop. Another reason to visit a specialist is that they will often match prices found on the internet and are likely to offer free fitting as well.
Sound
Head unit integrated amplifiers have improved massively over the years with a move away from simple low-powered bridged amplification to MOSFET designs which were previously associated with higher-powered add-on external amps. Other moves to greater power include small additional voltage-regulator/booster boxes which usually hang off the back of the unit.
Power is increased still further on some ultra-high power units by having a separate power wire designed to connect more directly to the battery to combat voltage loss and thus increase efficiency.
Extra power produces more heat and this is not helped by the constraints of the space inside the unit and being mounted in the close confines of the dash. Unsurprisingly, this led to the introduction of head units with cooling fans mounted in the back.
Despite their sophisticated designs, they are not in the same sonic performance league as the average domestic hi-fi amp which at the very least has the luxury of having some space between its internal components.
Music used for testing includes loud and well-recorded piano, and tracks such as the massed brass section of Arturo Sandoval's A Mis Abuelos. This can cause a virtual audible meltdown on cheaper, lower-powered head units.
The emphasis on performance at high volumes has much to do with the 85dBA-plus levels present at speed in older cars - often the main recipient of a head unit upgrade.
Strange but true, all of the head units mentioned here would gain a huge audible leg-up fitted to a larger luxury car, which are typically able to register sub 75dBA noise levels at 70mph.
Page 2: Alpine CDE-9882Ri, JVC KD-G731 >
Page 3: Kenwood KDC-W7537U, Pioneer DEH-P6000UB >
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