Soul Electronics aims its headphones squarely at pop culture fans, with a list of endorsers including high-energy stars like Tim Tebow, Ludacris and Psy. The Soul Flex ($69) phones cater to athletic types who do a lot of bouncing around and sweating while listening to their favorite tunes. These earbuds compete in a crowded field of water-resistant sport headphones like the Sennheiser OCX685i ($80) and the Skullcandy Fix ($70) — and Soul Flex beat them.
The Soul Flex earbuds are mounted on fairly soft rubber loops designed to go over the tops of your ears and keep the headphones in place. The matte-grey, textured earloops have an antibacterial coating, according to Soul Electronics, though we didn't test this claim.
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Flat blue cabling exits the bottom of each earloop, with an inline mic/controller sitting just below the right jawline. An anti-tangle slider moves from where the cables meet to the inline controller, and a small shirt clip lets you secure the cable to your workout gear. The three-button controller handles volume and track skip (iOS devices only), play/pause, call send/end and voice commands.
You get the typical small drawstring pouch and extra eartips in four sizes with the package.
Comfort and Operation
The earloops' softness and flexibility made it easy to get a very comfortable fit in our ear canals in just a few seconds. The Soul Flex stayed on and maintained a good seal no matter how hard we shook our head in every direction. Initially, it was a bit of a struggle to get the Soul Flex off, though after a little practice we got the hang of it by unwrapping them from our ears, starting from the back. The eartips blocked out noises fairly well at the local gym, especially higher frequencies like clanking weights. We could listen comfortably to our own tunes over the thumpy dance music.
The IPX5-certified (resistant to a stream of water) headphones still worked after we squirted them a few times in the gym's water fountain, and they easily survived our sweaty workout. We had no trouble operating the buttons by feel, thanks to the controller's rubberized face and ends. All functions worked smoothly with our iOS devices, including two quick center-button taps to skip forward a track and three to go backward. The earbuds also appear to be sturdy enough to withstand reasonable regular use.
Hip-hop and dance music fit perfectly with the Soul Flex. The modestly boosted bass that strong down into the deep low end on the rap sections of Jay-Z's "Holy Grail" featuring Justin Timberlake. All the vocals sounded full and clear, with well-balanced mids and highs. Metal and hard rock sounded good, too, with Metallica's "Enter Sandman" delivering clear, punchy vocals and guitars, as well as powerful kick-drum presence.
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On John Coltrane's acoustic jazz classic "Blue Train," we heard very good tonal balance and crispness, with fullness in the horns. Likewise, on Pink Floyd's "Comfortably Numb," the acoustic guitars and vocals had plenty of detail, with a smooth, spacious overall sound.
Orchestral music was hit or miss, occasionally suffering from too much bass. The bass drums in Wynton Marsalis' recording of "Carnival of Venice" sounded like booming cannons. That heavy bass added excitement (and a sinister quality) to Eugene Ormandy's recording of "Carmina Burana."
If you need to break away from a workout to take a call, the Soul Flex will serve you well. In our tests, our call partner said we sounded very clear, and she didn't hear much of the street noise in the background, indicating that the mic rejected the noise reasonably well. Our partner's voice came through clearly on our end as well. We had no trouble using Siri's voice commands with our iPhone 4S, and we didn't notice any lag or lack of responsiveness.
At $69, the Soul Flex are a great buy, offering a secure fit, markedly better sound than other sport earphones we've heard and a smart overall design that stays put for any type of workout. If you want to be able to put them on and take them off constantly, the loops may slow you down; in that case, consider something like Sennheiser's workout-friendly CX685 ($69) or Skullcandy's Fix ($49), both of which provide very stable fits without the earloops. Otherwise, you can't do better than the full audio and comfortablefit of the Soul Flex.