Who says you need plugged-in speakers to let others enjoy tunes on your iPhone? Griffin's AirCurve Play offers an impressive sound boost like no other unpowered amplifier we've tested. If you own an iPhone 4, there's no denying that this $19.99 add-on is the king when it comes to battery-free audio enhancement.
Made of hard clear plastic, the AirCurve Play measures 5 x 1.6 x 6.9 inches; the iPhone 4 fits snugly in a removable rubber sleeve in the center. At 11.2 ounces, this accessory is bulkier than the rubbery Bone Horn Stand Amplifier (3.2 ounces), but much more portable than the unwieldy Clingo Parabolic Sound Sphere (1.2 pounds).
Only an iPhone 4 will fit in this AirCurve's dock, but Griffin sells a model that's compatible with the iPhone 3G/3GS. To amplify your sound, simply slip the iPhone 4 into the dock. You have to make sure, though, that the iPhone's speaker is aligned with a small hole in the AirCurve. You'll know it's aligned correctly if you can access all the buttons on the phone. If your iPhone has a bulky case, you'll have to remove it. A metal stand lets you rest the dock in either landscape or portrait mode.
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Using an internal "coiled waveguide horn" which channels and amplifies the sound from your iPhone's speakers, the Griffin AirCurve Play claims to add 10 decibels to your tunes. Unlike the other speakers we tested, this device consistently provided more volume than its manufacturer promised.
When we blasted Haddaway's "What Is Love" through the AirCurve, the speaker added a whopping 14 decibels to the dance classic (76dB versus 90dB). Our coworkers said they could hear our music from across the office. Virtually everything we played with the AirCurve sounded many times louder; whatever is going on inside the internal waveguide is working wonders.
Though the device adds plenty of volume, don't expect the richest, fullest sound. "I Got A Feeling" by the Black Eyed Peas was loud but slightly muddled. When we played the same song with the Bone Horn Stand Amplifier, we got a slightly quieter 84dB, but the bass sounded richer. Playing the song with Clingo's Parabolic Sound Sphere gave us 82dB and sounded dim.
When it comes to portable passive amplifiers, you can't expect much more than this. The Griffin AirCurve Play is the best bet for iPhone 4 owners looking for serious sound without any batteries or wires. At $19.99, it's cheaper than both the Bone Horn Stand Amplifier and the Clingo Parabolic Sound Sphere, and it blows those two out of the water when it comes to added volume.