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fusionice

Member
Oct 19, 2010
42
3
Folks, I'm at my wits end and hope someone here can help. I purchased a Mekede M300 Android head unit (I believe this is a rebranded Joying unit) over a month ago for my wife's Honda HR-V 2017. Installation was fairly straightforward and any minor issues that came up were able to be resolved messaging the seller on Aliexpress.

There is one major issue that remains which is a dealbreaker - call quality is absolutely horrendous while driving and/or with the air conditioner on.

I've tried:
  • Testing on multiple devices
  • Testing with and without an external 3.5mm microphone installed (unit has a crappy internal one)
  • Factory resetting
  • Adjusting "sound mix scale" and "power conditioning" values in unit settings with no noticeable improvement
What I believe is happening is some processing/filtering is being done on the mixed audio input from internal mic (and the external mic, if plugged in). AC or road noise drowns out my voice and I cannot be heard well on the other end. No idea how to avoid this...

Does anyone have any suggestions or solutions? Attaching system info if it helps identify the device.
 

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surfer63

Senior Member
May 4, 2010
3,705
1,389
Zwolle
hvdwolf.github.io
This is a major issue with all of these Chinese head units. They do not use noise-cancelling microphones.
As soon as "ambient noise" like airco, ventilation, tyre noise, wind noise, engine noise, etc. becomes too loud, you can forget it.
Even a 10 euros/dollars investment in a cheap noise cancelling internal mic (so two cheap mics instead of one cheap mic) would already be a great difference.
Even the cheap units are so powerfull that simply using two very cheap mics and some algorithm to separate the "general constant" noise from the "differentiating" signal (voice) would make a huge difference.

Maybe you could try with a USB headset to see if you can use a USB microphone for a phone call. If it works you might purchase a USB-cancelling microphone. I must admit I never tried that as I don't do phone calls in my car.
 

fusionice

Member
Oct 19, 2010
42
3
This is a major issue with all of these Chinese head units. They do not use noise-cancelling microphones.
As soon as "ambient noise" like airco, ventilation, tyre noise, wind noise, engine noise, etc. becomes too loud, you can forget it.
Even a 10 euros/dollars investment in a cheap noise cancelling internal mic (so two cheap mics instead of one cheap mic) would already be a great difference.
Even the cheap units are so powerfull that simply using two very cheap mics and some algorithm to separate the "general constant" noise from the "differentiating" signal (voice) would make a huge difference.

Maybe you could try with a USB headset to see if you can use a USB microphone for a phone call. If it works you might purchase a USB-cancelling microphone. I must admit I never tried that as I don't do phone calls in my car.
Thanks for the info. Any recommendations for a replacement mic? I already tried purchasing a rather cheap one on Amazon that didn't make a noticeable difference.
 

firstbob

Member
Jun 4, 2021
45
3
I tested hypercardioid microphone and results were pretty good, but it has to be mounted near your head. Problem I have is that internal microphone, the one on the display, is still on. I'm thinking of de-soldering it as it's not too difficult to access.
 

fusionice

Member
Oct 19, 2010
42
3
I tested hypercardioid microphone and results were pretty good, but it has to be mounted near your head. Problem I have is that internal microphone, the one on the display, is still on. I'm thinking of de-soldering it as it's not too difficult to access.
I read about this and didn't want to have to do it if possible. Was call quality acceptable with the hypercardioid microphone? Can you provide a link?
 

firstbob

Member
Jun 4, 2021
45
3
I read about this and didn't want to have to do it if possible. Was call quality acceptable with the hypercardioid microphone? Can you provide a link?

It's like this one: https://www.aliexpress.com/item/1005002433011687.html I specifically was looking for cardioid microphone that does not pickup lower frequencies, this one starts at 50Hz.

It could be a bit louder ( gain was set to medium ) so it's probably not perfect, but results from directional pickup were good.
 

fusionice

Member
Oct 19, 2010
42
3
It's like this one: https://www.aliexpress.com/item/1005002433011687.html I specifically was looking for cardioid microphone that does not pickup lower frequencies, this one starts at 50Hz.

It could be a bit louder ( gain was set to medium ) so it's probably not perfect, but results from directional pickup were good.

Thanks, I'll look into that one.

When you say that you set the gain to medium, is that some setting on the headunit? If it is, I could not find a similar setting on my unit.

@surfer63 I've seen one of your posts breaking down different values in the "config.txt" file. Could mine be a culprit? It is set to "persist.btmic.gain=8"
 

firstbob

Member
Jun 4, 2021
45
3
Thanks, I'll look into that one.

When you say that you set the gain to medium, is that some setting on the headunit? If it is, I could not find a similar setting on my unit.

@surfer63 I've seen one of your posts breaking down different values in the "config.txt" file. Could mine be a culprit? It is set to "persist.btmic.gain=8"
Browsing through engineering menus I saw the mic gain settings. I found it after testing so I did not play with it.
 

mastrv

Senior Member
Jul 1, 2010
137
32
On my head unit, a TEyes FYT sc9853i unit, it did not have an external mic connector. I modified the harness so that my stock car microphone could be used. I soldered a connector directly to the internal mic location and removed the internal mic. It was located on the side panel where the touch controls are located. It is easily accessible from behind through a separate removable cover panel. Not sure if yours is the same. The stock microphone is located just above the drivers sun visor. I have a North American Kia Sorento 2012 SX.
 

firstbob

Member
Jun 4, 2021
45
3
On my head unit, a TEyes FYT sc9853i unit, it did not have an external mic connector. I modified the harness so that my stock car microphone could be used. I soldered a connector directly to the internal mic location and removed the internal mic. It was located on the side panel where the touch controls are located. It is easily accessible from behind through a separate removable cover panel. Not sure if yours is the same. The stock microphone is located just above the drivers sun visor. I have a North American Kia Sorento 2012 SX.
I think it's likely that all 9" (and probably 10.1") HU displays with capacitive buttons on a side are the same. I have TS10, relatively new unit, and date on the that side board is 2019.
 

fusionice

Member
Oct 19, 2010
42
3
On my head unit, a TEyes FYT sc9853i unit, it did not have an external mic connector. I modified the harness so that my stock car microphone could be used. I soldered a connector directly to the internal mic location and removed the internal mic. It was located on the side panel where the touch controls are located. It is easily accessible from behind through a separate removable cover panel. Not sure if yours is the same. The stock microphone is located just above the drivers sun visor. I have a North American Kia Sorento 2012 SX.
Yes mine looks like this as well. How difficult was your modification? Did you need to build a custom harness/connector to keep the OEM mic? Seems pretty involved, but I'd give it a try if I just needed to solder a readily available part.
 

mastrv

Senior Member
Jul 1, 2010
137
32
If you have access to 4pda, the hardware forum has good write-ups on microphone changes and other hardware modifications. I use Google Translate for 4pda and it works well enough. This has info for an external mic:


I needed an external module for my head unit to work with the OEM amplifier. The module harness came with a connector for the OEM mic. It plugged directly into the microphone connector I added to the head unit.

It's a little involved, but not difficult. My soldering skills are very limited. Made a huge difference in the call quality.
 

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    @surfer63 I've seen one of your posts breaking down different values in the "config.txt" file. Could mine be a culprit? It is set to "persist.btmic.gain=8"
    This one is unknown to me. Like mentioned: I don't do phonecalls in the car and never even looked at this one. I really don't know.