Saturday, January 11, 2014

Plantronics M165 bluetooth headset teardown - Making a hole for the microphone to fix the low volume and make the other person hear you better

Some month ago I decided I should get a Bluetooth headset for my smartphone, mainly to get less RF to my head :-)
After some research and reviews reading activity I opted for a Plantronics M165 Marque 2 (I bought it on Amazon, they always have a fantastic customer service).
It looked nice, with a practical "hear plugging" system, and the reviews were good.

Effectively the headset is very nice, very light, and fit perfectly in my hears.

BUT, there is an issue, a big one (in my opinion).
The sensitivity of the mike is too low, if there is a bit of noise around me, the person I'm talking to hear the noise instead of my voice.
So, this Plantronics M165 Mk2 works nicely when I'm in a silent room, but if I'm outside near a road it is totally useless, I need to turn it off and recall the person without the headset. This happened to me so many times that I've stopped using this headset.

Just to be clear about the level of noise I'm talking about: when I'm in the office, in the outskirts of the city, then I go on the balcony: we are on the 4th floor, and the nearest road is at about 60mt. Here, the noise of the road is enough that I can't use the headset.

I asked myself why I can't use the headset with such a low noise... maybe that my headset is broken/defective? it is possible...
But I think there is a better explanation: this headset DOESN'T have a hole for the microphone.

Take a look at the following image, a photo of the frontal part of the headset.
There isn't any hole, it's all solid plastic, and the microphone is behind this plastic.
How can it hear my voice?

There is second mike (for noise reduction) that instead it's near some hole facing "the noise" on the opposite side of my mouth.
Here you can see an image of the hole near the "noise reduction" mike.
I've circled them in red because they are so tiny that even with a macro photo you can barely see them. They are very tiny, about 2-3mm x 0,5mm and are "trapped" between the plastic bezel of the headset.

In my opinion, this can't work well.
Any headset I've ever seen have a hole for the mike, why the Plantronics M165 doesn't have it?

Now, I think I understood the problem: no hole for the mike.
I have also decided that this headset is useless for me, because it can work only in a silent room, which is not the the typical situation where I want to use it.

So maybe I can find a way to fix it? If only I knew where exactly the mike is, then I could make a hole for it.
So, why not try to dismantle it? :-)

I always loved to dismantle things, and I know that try to dismantle a headset can be a one-way street. Sometime they are glued together, and they are so tiny that it's really easy to break something.
Anyway, I should at least try :-)

So here is my venture in dismantling and fixing my headset.
To dismantle it I've used some plastic opening tool and some mini screwdriver.

Typical plastic opening tool

After trying to put the opening tool in any spot I could find, I've been able to open my way into the headset.
In the following image you can see the partly opened headset.
In red I've circled the only existing opening on the headset, them are near the "noise reduction" mike. Through these holes the headset can listen for the ambient noise.
Circled in yellow there is one of the 5 clips that hold the headset together.

  Here are some other images of the partly dismantled headset.

After some more pulling and bending I've been able to open the headset.

In the following images you can see the external part of the headset.
Circled in Green there are the 5 clips that keep the headset together.
Circled in Red and Orange there are other 2 clips that hold the headset together.
These last 2 clips are very hard to "unclip" because them are very tiny, and you cant use the typical plastic opening tool to unclip them (because them are placed in the corer of the headset)

As you can see from the photo, the Orange one is missing, I  broke it during the opening procedure... :-(


Now we can take a look inside the headset.
Circled in red there are the hooks of the clips.
Circled in green the leds of the headset.
Circled in pink the switch of the main button.
Circled in yellow is the bluetooth antenna.
Circled in blue is what I suppose to be the "noise reduction" mike.

And where is the microphone for the voice?
Let's take a closer look...

 Look at the object circled in red, it looks very similar the the noise reduction mike (circled in blu)

Let me check better.. I can also slip a piece of paper under it, it definitely seem to be the voice mike.

Now I know exactly where I need to make a hole, on the external plastic of the headset :-)
So, let's drill a hole in this deaf plastic shell!
To make the hole I've simply used my old trusty Olfa Cutter


And after some hand drilling... Ta-daaaa!
Here is my modded version of the Plantronics M165 Marque 2, now with a hole for the mike, so that the person you are calling can hear you better :-)

Here you can see the voice-microphone through the hole :-)

I reassembled the headset, and I'm happy to tell you that it stay together perfectly, even with a broken clip.

Clearly the headset have now some sign of the surgery procedure it went over :-)


Now the headset works way better than before, and I can talk on the balcony of the office without any issue! :-)


  1. Do you need to open it or can you just create the mic opening? Also, does it make sense to create an opening for the noise cancelling mic?

    1. You can just create the mic opening. I dismantled it because I didn't know where the mic was.

      I think that the noise cancelling mic doesen't need an extra opening, it already have a lot of opening along the bezel of the headset.

    2. Very cool. I have the same problem. Now I can fix it. Does anyone say anything like its too loud or do they hear extra noise?

    3. Nobody complained, my Plantronics M165 just works better with the added hole :-)

  2. Massimiliano, great hack. Turned my brand new M165 from a useless piece of junk into useable gear. Took my pocket knife, drilled out a quick tiny hole and tested it out. Callers report that background noise is now very minimal when I had originally thought the noise-canceling mic was broken. I can't believe this unit gets so many good reviews with this fundamental defect. Thanks for sharing.

  3. Massimiliano, thanks a ton for the tutorial! You gave me the bravery to test this out for myself!
    I used a dremel to make a small incision exactly where you did, then used a 2.0mm flathead screwdriver to widen the hole a little bit. Attached a few pics of the finished product. Thanks again hoss.

    1. Nice job!
      Thanks for sharing the pictures! Can I add your pictures in in my post?

  4. Thanks man :) I used a power drill with 1.5mm bit to fix mine. Will call someone tomorrow and see if it's better.

  5. Thanks! You Helped me to fix my headset!

  6. Thanks for the tear-down. Did it seem like it'd be difficult to get to the other side of the circuit board? I'd have liked to see how the battery setup was.

    1. The circuit board seem to be locked in place by 2 tiny plastics cylinder near the voice mic. The top of the 2 plastics cylinder has been melted a bit so that the melted plastics keep the PCB in place.
      To get out the PCB you need to break this melted plastic, and it's not something you can undo... if you break this plastic, the you need some other way to keep the PCB in place after reassembly.
      Other than that, there must also be something that keep the PCB in place on the other side (near the speaker), but from my photos I'm not able to understand what can be.

    2. Thanks, that is what I kind of thought by looking at the pictures. Probably have to attempt to drill out the cylinders a little bit, and attempt to re-melt them after you are done. That is if a replacement battery can be found.

  7. Thank you! I just made that same exact hole on my plt_m165 wich actually came out pretty decent, small and perfectly round. Now i know why my callers would complain so much about the excesive background noise. But, The reason i even attempted the procedure is because my MIC seems to have gone permanently mute. I can listen to music on it and all other audio but callers can NOT hear my voice through my bluetooth anymore. Ive never dropped it,never spilled any liquids on it or anything and it was working perfectly fine untill one day the mic just stopped working. All of the buttonts, controls and audio still work except for the mic. I was doing alot of research to see if anyone else has had this problem but i found nothing similiar. However i did run into THIS post and thought maybe if i drill that same hole by the mic my issue would be resolved. And sadly it did not work. Im thinking i should open it up to do some surgery on it maybe a detached wire in it or something but im not to much of a electronic tech type of person so i dont want to ruin it more than as is. I guess atleast i can still listen to music on it. Any suggestions as to what i can or should do to solve this? I need help please.

    1. I don't have any suggestion, sorry.
      The mic is soldered on the PCB, from the photos I have I can't see any wire than can broke... maybe that some component broke (a resistor, a capacitor... or even a soldering point)

  8. My problem is that the volume is too low. With it turned all the up, I can't hear very weel when I am in the car. Only works in quiet situations. Any way to increase the maximum volume?

  9. Bought a Plantronics M165 Marque 2 and I was affraid of what i saw here. I did a small test, I was speaking very close to a washing machine in my home, when the centrifuge was working. A lot of noise and guess what: I was able to hear perfectly, the other person was able to hear me perfectly - he was not aware of what I was doing. I call him to show that I was standing with my headset at 20 cm close to the washing machine. He was amased.

    Now, either I have a new revision of the hardware, either yours was fake - a loat of people are complaining about fake models on the internet.

    1. Thanks for reporting your experience, I'm happy that your headset works perfectly.
      I bought mine in 2013 from Amazon, exactly because it had a high reputation in the Amazon reviews.

      The build quality, the finish, and the packaging of my headset was perfect, so I don't think I got a fake one.

      Maybe that my headset was defective? I guess I'll never know...

  10. I thought i was the only one complaining (actually, the other side complained)
    Eventually i was using aliph jawbone for the last 12 years and i was able to ride my bicycles and talk.
    I certainly going to drill that hole now and fix this piece.

  11. Ok did it. Took the position of your drill and did it with a hot office attachment clip.
    Hole is clean and tiny. Looks original

    1. Well done!
      I hope it works better than before :-)

  12. I drilled my with a very small drill bit. I used a 5/64 inch bit but you could go smaller with a 1/16 bit. The hole in mine is super clean. Wish I could post a pick for you guys. If I figure out how I will. If you go this route, just be sure to put masking ir duct tape over the surface before drilling so the bit doesn't slip. Also, use extra caution while drilling, use very little force to penetrate the shell and back off once your through the plastic. I did notice a slight improvement in mic volume (I used a voice recorder to test before and after).

    1. Great job! I'm happy it helped you to get a better audio.

  13. Massimiliano, do you happen to have a picture of the connection of the speaker wires? mi plantronics came with the two headset-wires disconnectec and I don´t know were to solder them

    1. Sorry, I don't have any pictures of the other side of the circuit board, I did not take it apart.
      I've found a video where you can see the wire of the speaker, and the back of the board, but it's not very high resolution: