Motorola S11-FLEX HD Headphones Review


With the holiday season right around the corner, we have more than our fair share of shiny new Android devices to check out (see our Nexus 4 Review & Droid DNA review as examples). Motorola sent us a pair of their new S11-FLEX HD Bluetooth headphones, but with an excess of reviews in the pipeline we weren’t sure how to fit them in! Fortunately, Mark Jackson from was able to step up and take on the review. In addition to being an audiophile and headphone enthusiast, Mark also happens to be the brother of Phandroid founder, Rob Jackson.


The S11-Flex HD is a new fitness-minded Bluetooth headset from Motorola. Just released in October, it offers an array of features that, on paper, make it totally worth the $129 asking price. Training for a marathon? The S11-FLEX HD fits securely and offers up to 6 hours of music playback on a single charge. Do you spend a lot of time on the phone and listening to music? Switching between the two is seamless on the S11-Flex HD, and it works from up to 150 feet away from the paired Bluetooth device.

This all sounds great, but every device has its flaws. Can you safely invest your money in the S11 as a companion to your mobile device? Let’s take a look!

Build Quality – 4/5

The headphones are made mostly of plastic and rubber, but the build quality is solid. Both the earpieces and headband are flexible and sturdy, and nighttime runners will be happy to hear there is a 3M Scotchlite™ reflective inlay on the headband so you can better be seen at night. They do not fold or come with a case so I had to be careful putting them in my overflowing backpack, but they held up without a problem.

My favorite aspect of the design is the tiny size of the embedded battery and Bluetooth. Many wireless headphones look bulky and awkward but the S11 manages a relatively low profile look. Whether you consider the S11-Flex HD stylish is another story. I find it a bit too sporty looking to be used outside the gym, but that’s just me!

Worth a mention is Motorola’s “rapid charge technology” which gives the headphones 3 hours of playtime after only 15 minutes of charging. Or, if you are really in a rush, 5 minutes of charging will give you an hour of playtime.

Wireless Controls – 4/5

When you first turn on the S11-Flex HD, you are greeted with instructions on how to pair the device via Bluetooth and a notification of available playback time.

On the right earpiece is the on/off button, volume rocker, and your standard micro-USB charging port. On the left is the Smart Controls button which can be used to mute (single click), skip songs (double click), or switch to one of the 5 equalizer presets (press and hold).

Overall I am satisfied with the array of buttons, but to nitpick, I wish the on/off button was a switch since the LED indicator does not blink when the device is on (it is only activated during start-up, charging, pairing, and shut-down). Another imperfection is the Smart Controls button which I found a little sticky. Sometimes I had to press it a few times before it registered. Not a huge issue but I question its longevity.

Design & Comfort – 3/5

From the looks of it, the S11-Flex HD is a very sleek and ergonomic headphone. It is very light (weighing in at 54g), the earpieces swivel 45 degrees and extend downward to accommodate different size ears, and an optional inner headband is included for additional stability (more on this later). Unfortunately, this does not add up to a comfortable headphone in my opinion.

The biggest culprit is the half in-ear design, which means it is shaped like an earbud but the driver nozzle reaches into the ear. The earbuds are very large, making it virtually impossible to achieve a proper seal. Although this type of fit ensures that you are not completely cut off from your surroundings (a great thing for runners), it negatively affects the overall sound, especially the bass (more on that in the next section). Although I never felt as if the S11 was going to fall off, the nozzle would slowly drift outside my ear, so I found myself having to adjust them every 10 minutes or so.

The S11-Flex HD comes with four pairs of ear tips, and as with all in-ear headphones you should experiment to see which tips offer the best combination of comfort and sound quality. To my surprise, I preferred the stock medium tips over various third-party tips I own such as the Sony Hybrids. Comfort is the name of the game since the seal has already been sacrificed, and the stock tips offer a loose, comfortable fit.

One thing I am simply baffled about is the optional inner headband attachment, which does not seem to have much of an effect. Even at its tightest setting, there is still a good half inch between it and the back of my head, rendering it almost useless. This is a shame because it was a good idea that was simply executed poorly. All I think Motorola needed to do was add a few notches to the headband!

All things considered, the S11-Flex HD offers a secure but loose fit, something that is hard to come by in the world of headphones. Unfortunately this is at the expense of sound quality, which we will discuss in the next section.

Sound Quality – 2/5

The sound signature of the S11-Flex HD is significantly altered by the inability to achieve a proper seal, the result being a cold, dry presentation. The midrange is decently clear, but the bass does not extend well, nor does it have good texture, and the treble becomes harsh at medium to high volumes.

The built-in equalizer helps achieve better balance depending on the type of song you are listening to, but it does not improve the overall sound quality by any means.

Motorola advertises “better than wired HD sound” but frankly this seems like marketing jargon. Not only are there better wireless technologies out there for music (Kleernet for example), there is a high frequency hiss that can be heard during quiet and slow parts of songs. Some people will find it more annoying than others, but it is noticeable nonetheless.

To put it simply, the S11-Flex HD does not sound like a $129 headphone. Heck, there are $20 headphones that sound better than these. A case in point is the $15 Koss KSC75 which is my go- to workout headphone. That might be an unfair comparison since the KSC75 is not wireless and it utilizes a totally different form factor (clip-on), but it shows that you don’t always get what you pay for.

Call Quality – 5/5

If there is one area where the S11-Flex HD excels, it is call quality. I had no issues when talking to people using the S11-Flex HD, although one person mentioned that I sounded louder than normal (could be considered a plus). But out of all the possible problems, this is not a bad one to have.


The S11-Flex HD brings a lot to the table in terms of features, but its ergonomics were not able to match the sleek design. The earbuds are simply too large for a comfortable fit, which causes a domino effect on the sound quality. Obviously the size of user ears varies, but these earbuds are ginormous.

The lack of wires is liberating, but anyone who demands even mediocre sound quality will not be happy with these headphones. They function well for phone calls, but these were designed for music and phone calls, and unfortunately I cannot recommend them for the former.

All things considered, I find it hard to recommend the S11-Flex HD, even for people who fit the target audience. It offers a lot on paper, but there are simply too many flaws in the design for it to be considered a good buy.

Rob Jackson
I'm an Android and Tech lover, but first and foremost I consider myself a creative thinker and entrepreneurial spirit with a passion for ideas of all sizes. I'm a sports lover who cheers for the Orange (College), Ravens (NFL), (Orioles), and Yankees (long story). I live in Baltimore and wear it on my sleeve, with an Under Armour logo. I also love traveling... where do you want to go?

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  1. Thanks for the review. I was considering getting one of these, but now I’m going to have to rethink my purchase.

  2. Glad I didn’t buy them.

  3. I’ll stick with my awesome rocketfish stereo Bluetooth headset.

  4. I have the S10 HD – love them…

    1. Same here w/the S10 HD model, the sound quality was awesome. I say was, because I left them up unattended for 10 minutes in a dept. store dressing room, & nowhere to be found upon return.

      Despite the review, I’ll probably pick up a pair of these once they hit a discount site such as ALL4CELLULAR, WOOT, etc……
      I got the S10 HD model for $24.99 from WOOT. I imagine a similar sale will also come around, as the MSRP on the S11-FLEX HD will keep most away until a more reasonable price is available.

      1. Hate the s10. The s9 was the last good pair of these. My s10s lose the buds daily. I just stopped wearing them. Either way it is impossible to use either while cycling. Is it the wind that blows the bluetooth waves and disconnects the music?

        1. Totally forgot about the loose-fitting earbuds w/the S10-HD’s.I just went w/o & found the fit to be surprisingly comfortable enough for use,not that this would be acceptable to most users,admittedly.

          I may pick up a pair of the S-9’s in the meantime until the S11-FLEX HD’s drop in price.

        2. I have owned all three models and never had a wind problem. I ride 150 miles per week.

  5. I bought the white labron James beats sport headphones at newegg for $119 no tax free shipping vs $149 way better though not wireless. to go with my white labron James note 2.

    1. Doesn’t make sense… Why would Labron James anything be white?

  6. For those that don’t care to have another gadget to tote around & don’t care for both ears being covered,I highly recommend the standand one-ear BT from MOTOROLA ,the ELITE SLIVER.Great call quality,customizable SMART BUTTON & surprisingly loud & clear audio,which is also customizable w/the MOTOSPEAK application


    Make sure ROB pays you for your time & contributions to the site…… :P

  8. I have the Motorola SF600 and they are amazing.

  9. In my opinion, the best bluetooth headset is the combination of a Jabra Street and a set of Denon AH-C360 earbuds. Both together is only $80. Best setup ever.

  10. I bought a pair of these, and at least from my experience, I’ve been really happy with the sound quality. I’m not sure if it makes a difference, but I’m using it with a Droid RAZR MAXX HD, which supports the newer AptX audio codec. I’ve generally found the sound quality to be very good, haven’t really had the problems described in the audio section below. I’d say the sound compares favorably to my Klipsch s4i wired earbuds. For what it’s worth, I haven’t had a problem with achieving a proper seal though, so perhaps that makes a difference.

  11. Great review
    I currently own the s10hds and Ill stick with them :)

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