A Bluetooth device review: KN308 from AliExpress of China.

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This a bluetooth named “KN308” device is from AliExpress seller who in China. I bought it for about 4 USD, and took over a month to hold in my hand.


I’ve been teared down so easily (just pulled each different side of plastic case) and checked what components used in.  Some solderings are seems so weak, so I need to reinforcement work for thes.


Then I have tested on my car with AUX input thru iPhone4 and iPhone5. KN308 notices with a female voice but unclear. And found a problem mic not works – It was a component defect. So I need rework to soldering new mic component from other wasted device – 3mm diameter an 2mm depth condenser microphone. Finally it works well, but only recording function works on iOS devices, not any Androids. Music, Phone call works with a single button well, but talk or recording thru Bluetooth didn’t worked in my Android devices. It seems to a problem of bluetooth protocol compatibility.


This device displays bluetooth battery state on iOS state bar on screen, I can use it for my music and talk controller on the street. Actually connection quality is not good for while moving, it is continuously tickering by shortley lose audio packet.

Audio quality is little bit strange in lower frequency. There’s less bass, but high frequency is too much. I can hear well most of voices and instruments as like hihat, guitar and violin, but such as drum and bass guitar distorted to less. So I hear music with cheap dynamic open in ear headphones to make it balanced for Hi-Fi.

I don’t think this device is well made, but some people who like me, maybe can enjoying well for handheld portable music and talk device. But not for normal people if you don’t have soldering iron.

Positive features:

  • A2DP, control in single button allowed.
  • No volume control, must be adjusted in host device like iPhone.
  • You can talk if you have iOS device, not for Android – Android can sens mic but not work.
  • Small battery inclued inside, it works about 5 to 6 hours for listening music.
  • iOS can display internal battery how long left on top state bar.
  • iPhone4 works with this.
  • Treble frequency too modulated to higher, bass relatively less.
  • Little bit hard to using on the street while moving anywhere.