Thank you Mixcder for sending us this Bluetooth headphone to review!

I have long been passionate about good sound. I was spoiled as a child, as my dad had a great sound system, though I didn’t realize how good it was until I moved out and no longer had access to it. Once I came to realize how bad cheap sound can be, and how good things can get, I have since been on a quest to be able to enjoy all content – music, games, movies, and more – with the best fidelity possible.

Once I got my home theater system sounding great, I then turned to personal audio. I have since found nice earbuds, and I also help my friends and family find headphones that make them happy. For listening at my desk, I prefer open-backed headphones, because they tend to have a more 'real' sound - there is a certain spaciousness that only real space can provide. Also, it's generally a benefit if I can hear someone calling for me when I'm playing a game at my computer. (This is less true while listening to music at the office.)

As great as open-back headphones can sound, they are simply not practical for all use cases. In the most extreme case, you are on public transportation, or even on an airplane. Not only do you not want to hear your neighbors, but your neighbors almost certainly don't want to hear you - open cans share both ways. At that point it's usually best to use sound-isolating, or noise-canceling headphones. The Mixcder E9s are of the latter type.

Active noise-canceling headphones work on a unique premise: in addition to getting a good seal on your head to block out external sounds, they also have a microphone on the outside that records ambient noise and plays back a phase-shifted version of that signal back towards your ears, which leads to silence.

If you'll forgive the physics lesson, all sound is varying levels of pressure. A single note or tone vibrates at a certain frequency, or vibrations per second, using a unit called Hertz (or Hz). As an aside, the reference note for most modern music is A4, or the 49th key on a standard full-size piano. This frequency is set at 440Hz; each A of an octave above or below is half or double of that value. The human ear can hear a total of approximately ten octaves. (Please excuse the musical digression.)

The relevant part here is that in order for a speaker (large or small; headphone or large speaker and anything in between) to reproduce a sound, it must vibrate at exactly the same rate as what the source material or recording has. This is true of all loudspeaker technologies; everything from dynamic drivers (common cone speakers) to domes to ribbons to piezos to electrostatics and everything in between; they all operate through vibration. Sound waves are often represented as the mathematical sine wave, and if you add one sine wave to the same wave exactly 180 degrees out of phase - where up is down and down is up - they add together and you get zero.

It seems crazy that you could actually experience this in the real world; you might think that adding two signals together would always make it louder, not quieter, but it really does work. So, by recording the sounds outside of the headphones, and playing back the phase-shifted signal in real time, all of a sudden you hear silence. Of course, just like sound reproduction isn't perfect, neither is noise canceling. But it works better than it should.

The noise canceling on the E9 works pretty well, though I think there is room for improvement. While we don't have too many pairs of noise-canceling headphones, we do have another pair, and it's the Monoprice 10010. (They are less expensive, but not wireless/Bluetooth.) The Mixcder seems to cancel lower frequencies out better, while the Monoprice cancels out the midrange a bit better. I found the total perceived volume reduction to be a bit better on the Monoprice, but many find that lower frequency noise is more bothersome, so it really depends. Both do a very good job of significantly reducing the volume of external noise.

The Mixcder E9 is Mixcder's new flagship headphone, and it gets a lot right. I have always found that 40mm dynamic drivers are a great sized driver, as some of the most balanced headphones I've heard use those. I find that these headphones are also well balanced - if ANC (active noise-canceling) is turned on. When it is off, they still sound good, but a bit more bassy than is my preference, but nothing is missing. Like most headphones, I'm sure the top octave could use improvement, but there's not too much up there anyway (if you are young enough to even hear it).

You can listen to them using either Bluetooth, or a wired connection. I have tested them quite extensively, using both Bluetooth and wired modes. Bluetooth mode works quite well on my phone, and is almost entirely without connectivity issues, and the battery life is also excellent. I've used it for several days at a time in between charges; it's really great. I did have some trouble with my USB Bluetooth adapter on my desktop; it worked, but would occasionally drop out. On my other devices it's worked well.

When you want the best audio quality, wired is always the way to go. This is certainly true with these headphones as well. They work perfectly without noise canceling enabled when connected via a wire, but I think they sound better with it on. It's also a bit louder, which shouldn't matter for most things, but on super-low-power headphone jacks like on the Nintendo 3DS, that extra bit of loudness makes all of the difference. It works quite well and sounds great on the 3DS with noise canceling enabled.

The microphone that is built into the right earcup works okay, though from what people tell me, I sound a bit muffled to them over Discord. It's strange, because at least with my phone, I found that a recording of my own voice sounds just fine. No one on the phone has complained about the sound of the headset; just connected to my PC over Bluetooth. The microphone is not accessible at all with a wired connection.

The headset has the noise-canceling on/off switch on the left side, and the power and volume buttons on the right side. The power button also doubles as a play/pause button while in use. You can also hold the volume up/down buttons to switch tracks. I have used other Bluetooth headsets with a similar button config, but these buttons have a nicer feel and I found it more reliable in operation as a result.

When it comes to comfort, that is always one of the most important aspects to any headphone. It doesn't help that I have a large noggin', which is always a challenge; I have reviewed several headsets over the years that didn't even fit. Thankfully, the Mixcder E9 does fit quite well, and has an excellent variety in supported head sizes. The earpads are good but not great; they are leather-like, and have a reasonable depth, but are a bit hard in comparison to the Monoprice 10010 mentioned earlier. If these headphones had softer pads, I think it would really help. Otherwise, the clamping force, headband, and everything else is pretty comfortable. On the plus side, it is possible to replace the earpads, but you would have to glue the replacements to the ring that the existing pads are glued to. They would just snap back on. One other point is that these headphones are pretty warm after extended use.

My brother, who is another audio nut like me, tested out these headphones and was quite impressed with the sound quality, especially for the reasonable price and feature set. I absolutely agree. I have been using them for more than a week, and I find that the Mixcder E9 is a great-sounding headset and an excellent value. If the pads were a bit softer, the comfort could be improved. I hope Mixcder will consider that feedback and make these even better!