I've owned the BlueBuds X for a few years, mainly as a running headphone. I'm only reviewing them now because I feel that at their current price (~$70), they make a really great deal in the market, even today.
Fit and Form
The headphones are well designed. Their micro USB charging port is hidden underneath a snap-off cap on the left earbud. The battery resides in the earbuds themselves, along with a microphone, pause/play, and volume button brick on the left side of the earphones. The earbuds fit me well without their included honeycomb stabilizers, which fit in your concha like the EarLocks on Audeze's iSine series do.
Included is a very nice hard-case, which latches with a magnet and is supremely portable.
Also included are a set of clips that shorten the cable by holding them folded up behind your head. This allows a snug fit without the cable bouncing around during exercise, tearing them out of your ears. Microphonics were obviously nonexistent, given that the cable has virtually no room to move, even when in motion.
JayBird advertises that these earbuds are covered with a Liquipel nano-coating to resist damage from sweat and splashes of water, which I've found to work well. I haven't had any build issues whatsoever over my two-ish years owning them.
One issue I found with the mic controls themselves is that whenever you increase or decrease the volume, the audio is temporarily cut out and a beep is heard, which is helpful to confirm that you pressed the button. However, I would imagine that the actual change in volume resulting would be notification enough.
These paired with no problems with everything that I attempted, including two phones over time, my computer, my laptop, and my portable player.
These use the Bluetooth 2.1 standard, which is very outdated, but still works well enough for me given the expected quality-of-audio from a pair of work-out intended IEMs. They deliver a practical maximum of 320kbps, which worked just fine for me.
A personal issue that I had with the design of these headphones was that I have particularly small ears, and these are particularly large headphones, given that the battery resides in the earbuds themselves. These stick out of my ears pretty comically, if I'm honest, but I found that once I sacrificed a little bit of dignity, I very much enjoyed the experience of these for their use-case.
If you're looking to purchase these now, and I would still recommend them (more on that later), don't come into it expecting a beautiful, detailed sound signature. These have a V-shaped sound signature, without exceptional detail, and a bit bloated bass. However, I found that when in motion, I stopped paying attention to those minutia and was only really looking for a reasonably pleasant sound, which these provide.
Soundstage is inherently very claustrophobic, and imaging and separation are not stellar, but for IEMs, and particularly wireless IEMs, I found myself satisfied with them in use.
Recommended genres include hip-hop, rock, EDM, electronic, and most bass-heavier genres.
Songs used: Monster by Kanye West, Tentacles by Noisia, and You Want it Darker by Leonard Cohen
The bass on these is pretty massive. It isn't particularly detailed and is relatively slow and syrup-ey. However, when running or exercising, I found that I tended to listen to generally more bass-emphasized music, and that these headphones did a more-than-good-enough job handling that music. Although it is bloated and bleeds quite a bit into the mid-range, the bass has good slam and punch without being too obnoxiously slow or echo-ey, and was, in their intended use-case, enjoyable.
Key descriptors: big, bloated, and punchy
Songs used: While My Guitar Gently Weeps by Jake Shimabukuro, Did We Live Too Fast by Got a Girl, and Coming Home by Leon Bridges
The mids are where I encountered an issue with the bass, surprisingly. In the picking of "While My Guitar Gently Weeps", I found that I was hearing a distinct bass impact where I knew there was not intended to be one. This was a very noticeable effect of the bleed that the bass suffers from. Beyond that, as I found myself noticing it mainly when listening specifically for this review, the mids are pleasantly presented, with warmth and clarity that I was satisfied with. They were a little bit round and puffy, if that makes sense, masking detail in their presentation. Given the sound signature, they are noticeably recessed, and some vocals may seem a little distant, but it was, again, a non-issue in their intended use.
Key descriptors: round, warm, and recessed
Songs used: 22 (OVER S∞∞N) by Bon Iver, Fitzpleasure by Alt-J, and Holy Ghost by BØRNS
This is where I can complete my impression of the sound signature. It seemed that it was almost like a reverse check mark, as opposed to a true "V", with the treble falling slightly below the bass in terms of emphasis, and the mids tailing behind both. However, the treble is, thankfully, relatively detailed in comparison to the other ranges, and is rarely sibilant. I found that I could get through "22 (OVER S∞∞N)" without getting a headache. Although they are relatively detailed, I wouldn't stretch to call the treble airy, as it seems more focused and direct than I feel that classification implies.
Key descriptors: clear, focused, and distinguished
Minutia and Miscellaneous
The newer models of this series come with a slew of convenient features, including their smaller size, arguably better design, and the adjustable sound signature of their newest model. However, I found that given what I use these for, I did not need anything more than what these provide in terms of performance or features.
For all the critique in the "sound" section, I really enjoy these headphones. They don't necessitate a bitrate higher than what they can supply for their use, and the sound signature, for its flaws, is satisfying and pleasant to listen to when your focus is elsewhere. I couldn't see myself reaching for these for at-home listening, but they fulfill pretty much everything I need for an exercise set, and at approximately $70 as of now, they seem to be a very good deal given their feature set.
These headphones were not provided to me by JayBird, they were purchased purely of my own accord. I am not being paid by anyone to write this review, to endorse the product reviewed, or for the content that I put in the review.
These headphones were powered by an Astell&Kern AK Junior, a Google Pixel, and by whatever soundcard is in the motherboard of my computer.
I have had these headphones for about two years, and they have been my main driver for running during that time.