Kensington iPhone car cradle pumps up the volume

The Kensington Amplified Car Cradle for iPhone isn't the first accessory that boasts to passively amplify audio output of Apple's iPhone, but it may be one of the first designed at in-car navigation use.

The device consists of a rather bulky cradle with a pair of spring-loaded metal arms that hold the iPhone in place over a set of hollow lower arms. The springy arms have enough flex in them to allow the phone to be inserted and removed with one hand and have enough give to accommodate protective skins, but not hard cases.

Its lower arms are spaced in such a way that they don't interfere with connecting a 12-volt charger (not included) and are hollow to allow sound to pass to and from the iPhone's microphone and speaker, respectively. Both arms have  molded rubber inserts that protect the iPhone's finish and ensure an audio seal with the amplifying channel. The cradle ships with swappable inserts for the iPhone, iPhone 3G and 3GS, and the iPhone with a case.

The right arm has a foam insert that cuts down on wind noise a bit, but the lower left arm is where the magic happens. As the sound passes through the hollow left arm, it is routed through an amplifying channel that increases the volume as the sound exits a horn-like apparatus on the left edge of the device.

Although the Sound Amplifying Cradle is designed for navigation applications, with Magellan's iPhone app featured heavily in Kensington's promotional materials, the cradle doesn't enhance GPS reception like TomTom's and Magellan's cradles do; and the passive nature of the cradle's amplification means that it will work just as well with any app that uses the iPhone's loudspeaker, including audio playback and  speakerphone.

We only recorded about a 5 decibel to 10 decibel increase in volume from the driver's seat, which doesn't sound like a lot, but is certainly appreciable in practice. More importantly, the amplifier channel aims the audio at the driver's head, rather than the kneecaps as the iPhone's bottom mounted speaker does. Combined, these two changes add up to a serious increase in the perceived volume of the iPhone.

The cradle includes a pair of mounting options to keep it in place while driving. The first is a suction cup mount with a long flexible arm. The arm is fairly easily bent into most positions and holds firmly, but at its straightest, there is a bit of wiggle over rough roads. The second mounting option is a small adjustable vent mount that should attach to most vehicle's dashboard air vents. While mounted, the cradle will rotate 360-degrees for landscape viewing.

For about $39.99, the Kensington Sound Amplifying cradle is a bit pricey for what is essentially a well formed bit plastic with no active features. However, it makes good on its claim of much louder sound coming out of the Apple iPhone, making it much more audible over road and wind noise.