H2O Audio Flex All Sport Earphones
(4.5 star rating)
With the in-ear earphone market growing at an increasing rate, so is the number of manufacturers trying to stake out their niche. The folks at H2O Audio, as the company’s name implies, have focused on developing waterproof audio accessories – earphones and iPod cases that will survive more than just a light sprinkle. We previously reviewed their Surge headphones model and came away impressed. Their latest and most reasonably-priced earphone, the Flex, promises to survive under 3 ft of water for 30 minutes – more than long enough for the average aquatic workout - and deliver full and clear sound through rain and shine. Does it come through? Let’s find out.
The colorful shells of the Flex are made entirely out of plastic but feel quite solid overall. The cable entry point is protected by a flexible rubber sleeve and the strain relief on the angled 3.5mm stereo plug is one of the most impressive I’ve seen on an entry-level earphone. It is the cable itself that’s the real letdown, being a bit thin for my liking and very rubbery compared to that of the higher-end Surge. For an entry-level in-ear, however, the build quality is very reasonable and I’m the first to admit that despite my reservations, the H2O Audio Surge has now been with me for nine solid months of workouts.
The Flex, like the Surge, is completely waterproof, which I’ve tested by soaking it at various depths and for various durations. So far there has been no degradation in sound quality, at least not once the earphones dry out after each submersion. I can’t say how long the earphones will last with constant underwater use but for the occasional swimmer they should be fine. Naturally, the set is sweat-proof as well and the ability to simply rinse one’s earphones off under running water following a workout is very underrated.
Packaging & Accessories
The Flex comes in simple plastic packaging and includes the bare minimum of accessories – thick silicone eartips in three sizes and an H2O SealTight adapter for use with H2O Audio waterproof mp3 player cases. A small instruction booklet is also included, detailing some safety guidelines and the correct fitment process. Compared to H2O’s higher-end Surge model, the pickings are quite slim, but then something had to be sacrificed for the significantly lower MSRP of the Flex.
- Driver Type: Dynamic
- Driver Diameter: 9 mm
- Frequency Response: 20 Hz - 20 kHz
- Impedance: 16 Ohms
- Cable length: 3.9 ft (1.2 meters)
- Input connection: 3.5 mm plug
Fit, Comfort & Isolation
The dynamic driver used in the Flex has a diameter of 9 mm – average size for an entry-level earphone. However, the shells are on the smaller side and spherical in shape, allowing for very comfortable fitment with the right tips. There are only three sizes of eartips included with the Flex (in contrast to the pricier Surge) but most should be able to find a good fit with one of the included pairs. The flexible cable allows for comfortable over-the-ear wear as well but unfortunately also carries quite a lot of cable noise when walking or running. There is a sliding cinch on the cord, which can partly mitigate the cable noise, but over-the-ear fitment is still recommended for any physical activity. The passive noise isolation of the Flex is quite good due to the reasonable depth at which the earphones sit in the ear. However, the thinner silicone tips of the Flex don’t seal as well as the thicker rubber tips of my aging Surge and so the isolation still trails slightly behind the older model.
Testing note: All on-the-go listening was done using a Cowon J3 portable player with a wide range of tracks in mp3 (bitrates ranging from 128 to 320kbps) format. Critical listening was done via an optical-fed iBasso D10 DAC/amp using only WMA and FLAC lossless files.
The H2O Audio Surge surprised me earlier this year with the competency of its waterproof dynamic transducers – for an earphone marketed solely for its ability to shrug off water and sweat, the Surge is a very competitive performer when it comes to sound quality. The new Flex is doubly impressive, retaining most of the technical capability of its forefather while at the same time pursuing a sound signature rarely found among budget-level earphones – one that is balanced and spacious rather than intimate and bass-heavy. The bass of the Flex is quite possibly the most mundane aspect of its sound signature – controlled and fairly accurate but lacking in depth and impact. Low notes are heard but never felt – the Flex is definitely not for those who require sub-bass rumble or explosive, brain-quaking bass. Those who like more balanced sound will likely find the bass response adequate – there’s a slight mid-bass boost and a fair amount of roll-off but nothing that would make the Flex stand out from the crowd one way or another.
The midrange of the Flex is more impressive – for the most part it is free of bass bleed and very clear. As with the Surge, the transducers of the Flex aren’t the quickest in existence and as a result detail and texture lag slightly behind most mid-range earphones but the impressive clarity makes up for it. Due to the heightened sense of space afforded by the Flex, the midrange – vocals in particular – can seem a little distant compared to other similarly-priced earphones. However, next to the bass and treble of the Flex, its midrange is actually slightly forward, as is the case with the Surge. For a workout earphone such a presentation works especially well since emphasized bass and treble tend to be more tiring in general and the ear is already more easily fatigued during heightened physical activity. On the whole, the Flex is a very easy-going earphone, helped along by the overall smoothness of the response and laid-back presentation. Sibilance and harshness are absent from the lower treble response but a healthy amount of treble sparkle is present nonetheless. Treble clarity and detail are both good in the context of the smooth sound signature and extension is decent as well, though the Flex definitely won’t cause the Etymotic MC5 we reviewed recently any worry when it comes to treble response.
It is the sonic presentation of the Flex, however, that is most interesting – the soundstage is wide and extends farther in every direction than with most other entry-level earphones. The space is spherical in nature and positioning is quite convincing on the whole. Layering and separation are lacking slightly and the Flex isn’t as adept at separating a track’s background and foreground as higher-end sets but for a $30 earphone the presentation is very impressive nonetheless. Aside from the aging Soundmagic PL30, there are simply no entry-level earphones out there with the spaciousness and airiness of the Flex – and that alone makes it worth the asking price.
H2O Audio Flex All Sport Earphones
Any way one chooses to look at it, the H2O Audio Flex is a very solid entry-level in-ear earphone. Aside from the compliant fit, the most impressive aspect of the earphone is the sound – while those in search of deep, thumping bass will be unimpressed, the Flex can match far pricier models when it comes to clarity and space. It really doesn’t matter whether the Flex is a waterproof sports earphone that happens to sound good or an entry-level audiophile in-ear that happens to be waterproof – H2O Audio has once again managed to reconcile real-world usability with impressive sound quality, all at a very reasonable price. Will the flex survive daily underwater use as advertised? I can't say for sure but there are (pricier) sets that are likely better-suited for the purpose. However, as a reasonably-priced everyday earphone for music and movies that can also survive a sweaty workout, the Flex very difficult to beat.
Pros: Lightweight and comfortable; Water- and sweat-proof; Balanced, spacious, and surprisingly refined sound.
Cons: Not much in the way of accessories; Rubbery cable can be noisy; Bass lacks depth and rumble.
Rating: 4.5 out of 5