MTC Sound: controlling BD37xxx Sound Processors in MTCB Head Units (RK3066/3188)

Search This thread

peti007

Senior Member
Nov 20, 2014
125
16
Tatabánya
Dear 7floor,
I thinking of doing your great mod and I'm interested to buy an USB DAC too (KGL Unit + USB DAC SABRE ES9023).
Is there any way to disconnect the WM8731S's audio output from the BD37033FV's audio input and connect the USB DAC's audio output to BD37033FV's audio input? With this we could still use the fader/balance and subwoofer output with better sound card. Or the BD37033FV limits the sound quality and will no advantage?
 

7floor

Senior Member
Jul 20, 2006
236
179
Dear 7floor,
I thinking of doing your great mod and I'm interested to buy an USB DAC too (KGL Unit + USB DAC SABRE ES9023).
Is there any way to disconnect the WM8731S's audio output from the BD37033FV's audio input and connect the USB DAC's audio output to BD37033FV's audio input? With this we could still use the fader/balance and subwoofer output with better sound card. Or the BD37033FV limits the sound quality and will no advantage?

In theory, yes, you can do what you want.
You can check with datasheets for both BD* and WM* chips to find proper pins, and cut the PCB traces.
Then just solder wires from USB card output to BD* chip's input you just disconnected from the stock codec.
By the way, have you carefully read the post you are referring to? They wrote:
"If you want to build a serious car sound system, you have to make a digital out to your amp (or DSP) instead of using our head units line outs."

But I can't tell anything about sound quality. Personally I'm satisfied with what I have. I have no idea on how bad is the BD37033FV in terms sound quality limitation. Only can tell that I satisfied with my BD37534FV.
I have never seen any good research on how the WM8731 codec is bad if it is (noise level, bad AFC, whatever else?), and how external USB DACs are better - you know, those articles with AFC charts taken on professional equipment, noise levels etc.
I'm pessimistic about USB DAC mod. Sometimes people do what they BELIEVE is better, not what is ACTUALLY better. They heard about external DACs from the home Hi-End world or from PC world, and they think like "Hey, I would put an external DAC into this Chinese stuff and I'll get a Holy Grail!" - hmm :)
So fiddling with the external DAC is something out of my interest. I expect it will break an "ecosystem" - I mean all these functions like volume adjustment, background navigation mixing, rear gear mute etc. - for no noticeable benefit.

And you know... The car is not the place where you'll get the perfect sound. The engine/road/aerial noise, the noise from your climate control fan, sound reflections from windows which are pretty unpredictable. So is it worth effort at all? If you ask me why then I done my mod if I'm so conservative :) You know, my mod described in this thread is something different: I clearly knew that Chinese engineers have done something stupid, I knew how to do it right way and I knew that I'm able to do so.
 
Last edited:
  • Like
Reactions: xluisx

7floor

Senior Member
Jul 20, 2006
236
179
It might be good if when this error occurs during boot, 7floor has the equalizer retry access after receiving the BOOT_COMPLETED message. That might provide an opportunity to allow root access from SuperSU the first time, and quietly solve the problem afterwards.
Your suggestion makes sense. But it'll require some changes into initialization logic, which then will require testing to prove it is stable etc. And the benefit is too small: one need to configure SuperSU once after install. It's not something affecting everyday experience.
So, probably I would say: It is good enough as it is :) Sorry for laziness :)
 

7floor

Senior Member
Jul 20, 2006
236
179
Hello 7floor,
I made this mod and it working almost perfectly. The sound quality better than before, but I noticed a little problem. When I don't listen the music I hear a permanent background noise. It's only exists when the input focus on the system. Did you heard this issue before? Can you advise something for me?

Thanks and sorry my bad English
Babss

Yes, I heard it from a few people. I guess you are the second person in this forum, and people were discussing noise on Russian forum 4pda.
Some report they have a noise which depends on Volume (increases as you turn volume up), other report that they have the noise level constant, regardless of Volume.

Personally, I do not experience any new noise except I had already:
I have a little noise because of my installation - the 5-meter-long line-level RCA cables go to my trunk where I have my amplifier installed. And in a modern car it is almost impossible to fully avoid noise - they're so "digital-ish" :)
So I had some minor noise, even if I turn my head unit off, the noise was induced by the car's circuits to long line-level cables. To hear that noise, I have to sit quietly with engine stopped, and the climate fan turned off - only then I could hear noise from tweeters. That noise did not change after I done my mod.
Ah, yes, there is another kind of noise - when you turn the volume pretty high, 25 and above, another noise is starting become audible, and it is a kind of "digital", you know, as opposite to regular white noise.
This one I believe comes from inside of HU, because Chinese paid no attention on good separation of analog circuits from digital ones, and at high volumes we start hearing that.

And I still don't know, whether they got more noise after doing my mod, or noise existed before it. Nobody can answer for sure, you know. :) Some people even reported like they got noise with upgrade to latest firmware, Android part (sic!) Also, I had a thought, maybe people set their Treble too high after they got my nice-looking equalizer, so that the noise just became more noticeable? :)

So, may be it worth to start grabbing some statistics on this "noise problem" you and some other people have.
Can you answer the following:
- Your HU make / RK3066 or 3188 / MCU version / Firmware (stock/custom (author)/date)
- exact BD37*** chip model
- are you sure you hadn't this noise before mod?
- does the noise depend on volume or not?
- does it sound like "analog", white noise or more like "digital" noise?
 

peti007

Senior Member
Nov 20, 2014
125
16
Tatabánya
In theory, yes, you can do what you want.
You can check with datasheets for both BD* and WM* chips to find proper pins, and cut the PCB traces.
Then just solder wires from USB card output to BD* chip's input you just disconnected from the stock codec.
By the way, have you carefully read the post you are referring to? They wrote:
"If you want to build a serious car sound system, you have to make a digital out to your amp (or DSP) instead of using our head units line outs."

But I can't tell anything about sound quality. Personally I'm satisfied with what I have. I have no idea on how bad is the BD37033FV in terms sound quality limitation. Only can tell that I satisfied with my BD37534FV.
I have never seen any good research on how the WM8731 codec is bad if it is (noise level, bad AFC, whatever else?), and how external USB DACs are better - you know, those articles with AFC charts taken on professional equipment, noise levels etc.
I'm pessimistic about USB DAC mod. Sometimes people do what they BELIEVE is better, not what is ACTUALLY better. They heard about external DACs from the home Hi-End world or from PC world, and they think like "Hey, I would put an external DAC into this Chinese stuff and I'll get a Holy Grail!" - hmm :)
So fiddling with the external DAC is something out of my interest. I expect it will break an "ecosystem" - I mean all these functions like volume adjustment, background navigation mixing, rear gear mute etc. - for no noticeable benefit.

And you know... The car is not the place where you'll get the perfect sound. The engine/road/aerial noise, the noise from your climate control fan, sound reflections from windows which are pretty unpredictable. So is it worth effort at all? If you ask me why then I done my mod if I'm so conservative :) You know, my mod described in this thread is something different: I clearly knew that Chinese engineers have done something stupid, I knew how to do it right way and I knew that I'm able to do so.
Thanks for your complete answer!
My problem is the "Android sound". The high tones (treble) sounds like a very low bitrate mp3 (when listening high bitrate flac with Poweramp). I use Viper4Android, it helps a lot, but far away from good. I have to decrease the treble side a lot of V4A EQ. This is why I thinking of buying an USB DAC.
I don't want serious sound system for exactly what you say. (Noise in car)

"I expect it will break an "ecosystem" - I mean all these functions like volume adjustment, background navigation mixing, rear gear mute etc. - for no noticeable benefit."
The volume adjustment is working with the HU's and SWC volume buttons over @Petrows app. I asked to connect external DAC to BD* beacause I thought the BD* chip doing these function, not the Wolfson.

I will doing your mod and I will see the improvements :)
Thanks for your help and great work!
 

7floor

Senior Member
Jul 20, 2006
236
179
My problem is the "Android sound". The high tones (treble) sounds like a very low bitrate mp3 (when listening high bitrate flac with Poweramp). I use Viper4Android, it helps a lot, but far away from good. I have to decrease the treble side a lot of V4A EQ. This is why I thinking of buying an USB DAC.
I don't want serious sound system for exactly what you say. (Noise in car)
This definitely should not be happening. Are you confident you have your flac files originating from the good source, not something re-converted from, say, poor mp3? Do they sound well on your home Hi-Fi? Another thing, try disable V4A. This is nothing than additional layer of digital conversion with DSP effects, which is, on my mind, ALWAYS bad. Try maybe check your sound with some high quality test recordings, you know, those for sound quality testing.
I don't suspect the PowerAmp much as to sound quality it produces (I tried using it, and had no problems). But still, give a try to the Neutron Player maybe - it is positioned as a player for audiophiles :) At least it can do many interesting things such as 64-bit arithmetic, re-sampling, adding dithering; it has freely configured equalizer if you want (N-band parametric or N-band graphics, you choose). I am very happy with it.

"I expect it will break an "ecosystem" - I mean all these functions like volume adjustment, background navigation mixing, rear gear mute etc. - for no noticeable benefit."
The volume adjustment is working with the HU's and SWC volume buttons over @Petrows app. I asked to connect external DAC to BD* beacause I thought the BD* chip doing these function, not the Wolfson.
These functions are performed by BD37* only when current input is set to other than System - e.g. Radio, DVD, etc. When Input is System (Android), then all those is done inside of Android, and I'm not sure if it will work with USB DAC. And you may read the topic you linked to: the first post already mentions some of the problems. This is what I referred to as "breaking an ecosystem".
 

ojuniour

Senior Member
Feb 5, 2010
103
19
New Jersey
I'm getting " No device driver i2c-dev" Even though I have the driver at the right folder (system/lib/modules) with the correct permission 644. I have rebooted many times.. Same error.
Can you tell me what's going on? Thank you.
I'm on rk3066.
 
Last edited:

7floor

Senior Member
Jul 20, 2006
236
179
I'm getting " No device driver i2c-dev" Even though I have the driver at the right folder (system/lib/modules) with the correct permission 644. I have rebooted many times.. Same error.
Can you tell me what's going on? Thank you.
I'm on rk3066.
What ROM are you using?
 

ojuniour

Senior Member
Feb 5, 2010
103
19
New Jersey
What ROM are you using?
-----
MCU Version
MTCN-KGL-V2.72
August 10 2015 17:32:50
-----
ANdroid Version
4.4.4_18092015
-----
Kernel version
3.0.36+
[email protected] #387
Mon Aug 24 17:32:49 CST 2015
-----
BUild number
rk3066-eng4.4.4 18092015
-----

I hope that's enough infromation


EDIT: I am gonna try to update to the latest Malaysk rom (jan 12, 2016) and see if it helps...
 
Last edited:

ojuniour

Senior Member
Feb 5, 2010
103
19
New Jersey
But is it stock or custom ROM, I mean? :)
I've never tested my mod on a stock ROM, initial development and testing was done on Malaysk ROM from late summer '2015.

I installed the newest version of the Rom and it is working now even without copying the two files. Do I still need to do that?
 
Last edited:

7floor

Senior Member
Jul 20, 2006
236
179
Definitely a Modified Rom. Is that the rain why it can't funds the ic2 driver in the modules folder?
No, I've never tested it on a stock ROM, so if you had a stock, then I couldn't give you any advice.
Edit: I installed the newest version of the Rom and it is working now even without copying the two files. Do I still need to do that?
This is because Malaysk includes the two files required by my mod into his recent ROMs, I guess. Go check that, probably they already exist in their places.
So if you have it working, then I'm glad for you.
Why it wasn't worked for you before, it's a mystery.
 

ojuniour

Senior Member
Feb 5, 2010
103
19
New Jersey
No, I've never tested it on a stock ROM, so if you had a stock, then I couldn't give you any advice.

This is because Malaysk includes the two files required by my mod into his recent ROMs, I guess. Go check that, probably they already exist in their places.
So if you have it working, then I'm glad for you.
Why it wasn't worked for you before, it's a mystery.

The two files you provided already exist but I replaced them with the ones you provided anyway. Thanks!

---------- Post added at 04:14 PM ---------- Previous post was at 04:08 PM ----------

No, I've never tested it on a stock ROM, so if you had a stock, then I couldn't give you any advice.

This is because Malaysk includes the two files required by my mod into his recent ROMs, I guess. Go check that, probably they already exist in their places.
So if you have it working, then I'm glad for you.
Why it wasn't worked for you before, it's a mystery.

When I turn up the volume the left speakers just stopped working..I don't know why. Do you have a recommended minimum and maximum dB gain to use?
 

7floor

Senior Member
Jul 20, 2006
236
179
When I turn up the volume the left speakers just stopped working..I don't know why. Do you have a recommended minimum and maximum dB gain to use?

The default setting (-60 .. 0 if I remember it correctly) is something safe for all, close to stock levels, even a little bit lower than stock.
This definitely should not be the case of speakers or amplifier overload.
 

Airwin13

Member
Jan 14, 2016
21
7
I just completed the MTC Sound hardware modification. I am listening to my HU on the bench connected to my computer's 40W sound system (amplified two 3-way speakers / one subwoofer), running my infamous 'Test Tape' (actually it's mp3 now...used to be on cassette when I first got it 30 years ago, one of the pieces I used to test my sound system installs) . At first, my volume was low and I couldn't see what the app was doing. So I looked at the pic on the first post and noticed my Preamp was at -20 and my Loud and Equalizer buttons were off. So I just set everything just like that pic and whoa! I had to hurry and turn my volume down to 12/30. It was boomin! Sounds really good, and this is just on my computer's sound system; I haven't even put in my car yet. Can't wait:D Here is a pic of my wiring. I tacked the wire down with tape but when/if I go back in to do the mic mod I will use the proper wire tack tape in multiple places. I used 0805 1K-ohm resistors instead of the 0603 (I accidentally ordered the wrong size but it worked out) and 30AWG (0.0509 mm^2) wire.
Hi JEMShoe,
I also have the Joying unit like you. Do you maybe have another picture of the resistors which are located under the RK3188 board? So I could see where to solder the other ends of the wires.
 

Airwin13

Member
Jan 14, 2016
21
7
Bricked?

I have done the mod. I put a picture of it in the Attachment. But I think I bricked it, it won't boot up anymore. The illumination of the keys turn on and the Screen gets white for a few seconds and turns off again. After that the Keys keep flashing. I've made short video. Do you think i can rescue it somehow or is it gone?

Sorry I'm not allowed to post direct links or upload images yet.
Image: i.imgur.com/puLTITa.jpg
Video: youtu.be/SPux0QHwyzo

Update:
Ok I fixed it. I disassembled the whole unit and assembled it again. Now it is working. I think the problem was the flat white LCD wire.
So THANK YOU 7floor for the great tutorial and software.
 
Last edited:

peti007

Senior Member
Nov 20, 2014
125
16
Tatabánya
@7floor one questions
I made your mod on my HU and works fine. Now I can calibrated Radio sound with your equalizer, but the FM sound is much worst than MP3,internet streaming etc. FM have bad high tone. If I make also this mod http://home.scarlet.be/~spb27160/witson/Witson.html then FM sound will be better or not (high tone)?
Yes, sure
This is the same mod as @pauloxx linked?
https://translate.googleusercontent.com/translate_c?depth=2&hl=en&prev=search&rurl=translate.google.com&sl=ru&u=http://4pda.ru/forum/index.php%3Fshowtopic%3D695716%26st%3D300&usg=ALkJrhhsmbZPQ2BkSA3wXMHOQWBS24e_7g#entry44206991
@7floor: Does it matter what type of 1kOhm resistor I use in the new way of I2C Control Bus? http://www.electronics-tutorials.ws/resistor/res_1.html

Does anybody made @7floor's great mod with stock ROM? I read the developer not tested it, but I prefer stock ROM.
 

Top Liked Posts

  • There are no posts matching your filters.
  • 30
    Direct control of Sound Processor for Microntek Head Units based on RK3066/RK3188 processors.
    HuiFei, KGL, KLD, JY, and similar, generally discussed here: http://forum.xda-developers.com/android-auto/mtcb-android-head-unit-general

    WARNING! The hardware modification described in this topic, while being simple enough, still requires you to have at least average soldering skills and appropriate soldering iron that allows soldering of very small SMD components. Sample of suitable soldering iron is shown on the photo:
    soldering-iron.jpg
    Also, you will need a multimeter, any cheap one with buzzer will be sufficient.
    There is an excellent post by @JEMShoe, a must read: http://forum.xda-developers.com/showpost.php?p=63661855&postcount=39

    The goal of the modification

    Microntek Car Head Units based on RK3066 / RK3188 processors have so called Sound Processor IC made by ROHM, the BD37xxxx family.

    This sound processor has the following functions:
    - Three-band parametric equalizer with adjustments of gain in range -20dB – +20dB, frequency and Q-factor of the filter in each band.
    - Configurable loudness module with gain in range from 0dB to +20dB, and adjustment of filter frequency and the level of high frequencies suppression.
    - Setting of subwoofer output, including selection of signal source, cut-off frequency, phase, and gain.
    For more detailed technical information please refer to the datasheet: View attachment 3520723

    In stock implementation, this IC is controlled by another 8051-based controller (called MCU) which controls all the onboard hardware, such as display, hardware buttons, BT module, video switch, etc. The way it controls the Sound Processor IC is very limited and in some aspects wrong:
    - Instead of 3-band parametric equalizer, we have a 9-band graphical one, with strange logic – each of three groups of three bands controls a single hardware band, averaging their values; and the adjustments range is only +-10dB.
    - Loudness compensation does not use a built-in hardware circuit, but just adds some bass and treble, which is a way not the same.
    - Subwoofer output is fixed and cannot be configured.

    The MTC Sound module allows for direct control of all the built-in function the Sound Processor directly from Android, overcoming limitations of stock implementation, and allowing to tune the sound quality to the best, with only minor hardware modifications.
    Besides of that, in stock implementation, equalizer presets apply to any input, be it System, Radio, DVD etc. My experience tells me that it is desirable to have a separate equalizer settings per input. The Radio sounds differently than Media Player or DVD, so it needs to be adjusted differently.
    In addition, a Preamp value that can be found in Factory settings was pulled for live adjustment. It is needed to equalize the volume of different inputs.

    The software part

    1.equalizer.jpg2.balance.jpg3.settings.jpg
    The software can be installed without hardware modification, but it will not work. It can be used for evaluation, though, to see how it looks like and what settings it has.
    Make sure you have a rooted device, the Xposed framework installed, and you have some file manager that allows for file manipulations in system folders. I recommend the "Root Explorer".
    Find the files mentioned below in this archive: View attachment system-files.zip
    1. Copy libjnidispatch.so to /system/lib and set permissions to 644.
    2. Check if you have files i2c-0 .. i2c-4 under /dev directory. If they exist (typical for RK3188) skip step 3 and proceed to 4; if they don't exist (typical for RK3066) proceed to step 3.
    3. Copy i2c-dev.ko to /system/lib/modules and set permissions to 644.
    4. Download MTC Sound plugin from the Xposed repository (http://repo.xposed.info/module/com.sevenfloor.mtcsound) and install it. It will appear in modules in Xposed Installer, enable it there and reboot.
    5. After reboot, go to Xposed Installer, and check its Log. Watch for line "The Sound Control Status is:" (see below for possible statuses).
    The software brings the new Equalizer which will replace the stock one, and also it will be launched by hardware EQ button (if your unit has one).

    The statuses that can be displayed in the Xposed log:
    - No patch detected – either module is not active in Xposed, or device was not rebooted after activation.
    - mcu,No device driver i2c-dev – you have device which requires i2c-dev.ko driver, and you forgot to copy it where needed or set permissions (see step 3 above).
    - mcu,Exception com/sevenfloor/mtcsound/I2cBus$CLib – you forgot to copy libjnidispatch.so or set permissions.
    - No access to /dev/i2c-?; <some additional info> - despite existence of driver, failed to access i2c bus programmatically. Normally should never happen, but if happened, contact me for further investigation.
    - mcu,Error in write() 11 (no response from i2c slave) – programmatic access to i2c bus works well, but Sound Processor does not respond. Need to check soldering. Maybe there's no contact where is has to be, or you shortened something, or you messed with the wires making them wrong way around.
    - mcu,Error in write() 110 (no response from i2c slave) – same as above.
    - i2c,Channel x (x is a number) – everything is good, enjoy your sound.

    Note
    Starting from version 1.9.0, due to massive re-implementation of initialization logic, the statuses mostly change their texts.
    But they still have the same meaning as above, thus can be understood easily.
    Additionally, initialization steps are logged in details to system log with tag 'mtcsound' (viewed with apps like CatLog).

    The hardware part

    circuit-en.jpg
    Please see the circuit diagram above.
    Basically what we need to do is to re-route the I2C control bus of Sound Processor from the MCU to the Android Board.
    Find a 28-pin IC marked BD37<whatever>. It has a key - small dot or circle near the 1st pin. Pins are counted from that key dot, counter-clockwise.
    So that find pins 25 and 26, and using a multimeter, trace resistors connected to these pins, somewhere around the chip.
    Unsolder these resistors - this way you'll break connection to the MCU that needs to be broken.
    Keep the resistors, or throw them away if you plan to use new ones (e.g. bigger, easier to manipulate - not only SMD resistors may be used but also those with wired pins).
    Now find a 28-pin IC marked WM8731S, and with multimeter, trace resistors connected to its pins 24 and 23. The same rule for pin counting applies.
    Don't unsolder these resistors. Solder wires to their opposite ends.
    Other ends of wires solder to the resistors that you unsoldered (or to others you had for replacement), and opposite pins of the resistors solder to the pads that are connected to the BD37xxx chip.
    So that you will have the following traces:
    WM8731S pin 24 - resistor - wire - resistor - BD37xxx pin 25
    WM8731S pin 23 - resistor - wire - resistor - BD37xxx pin 26
    After soldering, carefully check the circuit with the multimeter.
    WARNING! Later in this thread, users who already done the mod share their experience, photos, drawings, etc.
    When doing the mod yourself, ALWAYS read this my post and refer to the diagram above.
    Use pictures from others to get an idea where the components are located, but think yourself, don't blind-follow others work.

    Mini-FAQ

    Q: So will the sound be much better after this modification, is it worthly at all?
    A: It will not make your hardware parts like amplifier and other audio circuits any better. But it will allow you to fine tune the sound to the best that can be achieved with all the features of the Sound Processor, which is not available in the stock. Many people say they get "incredible sound". I would say that I managed to tune mine to be "much better" :)

    Q. Would your software be useful without the HW modification part?
    A. No. In future, such a possibility might become available. Other developer works on MCU patch, and when/if he finish his work, I will update my software to work thru his modified MCU, so that without a HW mod. As I see the picture, it will take not less than a couple of months.

    Q. Please help me with the HW modification for my device XXX / YYY / ZZZ
    A. I'm not familiar with other devices than mine, and, unfortunately, I've got not very helpful pictures of my work. So if you can't follow above instructions yourself, then please wait for more experienced users with units like yours, when they do modifications and share their photos.

    Q. I've done the HW mod, and the software gives me the status "i2c,Channel x", which indicates success. I have sound from the Radio, but not from the Android / Media player. What's wrong?
    A. Some people reported an issue with the resistors at the WM8731S chip. They're fragile and can be easily fried/broken when soldering wires to them. The WM8731S chip is the Audio Codec for Android and with broken I2C control circuit you'll get no sound from Android. Please check with the multimeter and replace one or both that are broken. Use 1 kOhm resistors suitable by size.

    Q. I've got the status as follows: mcu,No access to /dev/i2c-?; su exit code 1
    A. Have you installed the SuperSU or one of similar super user managers? SuperSU has the option to allow SU during boot - just enable it and reboot.

    Q. Why the feature X doesn't work exactly as it worked in stock unit, or doesn't work at all? When will you fix it?
    A. As the MCU does not control the Sound Processor anymore, I had to re-implement many stock features in my software from a scratch. Example is the GPS application sound switch/mix. There are some other stock features that were not implemented -- either they are impossible to implemented, or I was not aware of their existence, or I just don't want to implement them because consider them not important. Anyways, ask for a specific feature in this thread, and at least I'll answer, whether it will be implemented and how soon.

    Q. You said that some features are impossible to implement. What these features are?
    A. Anything related to Sound control by the MCU alone, before Android gets loaded, for sure. Not sure what this may include, maybe something related to parking sensors beeps? Did this ever existed in stock? Other features except that also may appear impossible to implement or too hard to ever try to do that.

    Q. Where on your Equalizer are the sound presets like Pop/Jazz/Rock? And why my hardware EQ button which was switching these presets earlier, now just executes the Equalizer app?
    A. This is a good example of a feature that I consider unimportant and will never implement. These presets are nothing than a marketing bu11$41t and have nothing in common with a quality sound. Period.

    Xposed Repository link

    http://repo.xposed.info/module/com.sevenfloor.mtcsound

    Links to how-to posts by users who have already made the mod.

    KLD by @dazza007
    http://forum.xda-developers.com/showpost.php?p=63520630

    JY by @JEMShoe
    http://forum.xda-developers.com/showpost.php?p=63712823

    JY-UQ128 by @JrFaust
    http://forum.xda-developers.com/showpost.php?p=65587419

    KGL by @Tutti-frutti:
    http://forum.xda-developers.com/showpost.php?p=64460726

    ---
    My other work:
    - Xposed Volume Bar: http://forum.xda-developers.com/showthread.php?t=3246360
    7
    Thanks, but you must work on your ego. Instead of talking about 0-30 you could have said volume knob to lowest setting 0 vs highest setting 30. Which would have been easier
    to understand.
    You're welcome, but taking my work for free, you must not tell me what I must to do.
    Instead, you must carefully read posts, where I'm trying to help you, and ideally, you must try to understand them. Just because if you don't understand, it's your problem, not mine.

    If you really need somebody to teach and to demand support from, I can recommend the Chinese seller who sold you your unit -- at least you paid him money. Go ahead, tell him about his ego.

    So, my congrats: you win the "No Support" prize.
    6
    Update:
    Version 2.0.0:
    - Now also works on Android Lollipop 5.1.1 on MTCB/MTCC/MTCD head units

    Special thanks to @kumarai for testing!
    6
    New version 1.6.0
    Added new setting "GSM via Android" for some Bluetooth types that route phone call sound via Android board (BC6B seems to do that)

    There are reports that the sound of phone call cannot be heard after the mod.
    Examples are:
    http://forum.xda-developers.com/showpost.php?p=63967019&postcount=88
    http://forum.xda-developers.com/showpost.php?p=66083203&postcount=253

    It turns out that some types of BT modules outputs the phone call sound via the Android board, not directly to the sound processor chip. Seems like BC6B module does like that.
    So for those who lost their phone function with my mod, this new setting should help.
    6
    I am a HW engineer and several of my skills include Printed Circuit Board (PCB) layout, soldering and I frequently review PCBA manufacturing facilities (we own our own electronics assembly plant).
    Just a few tips and observations:

    1) Static electricity (formally known as Electrostatic Discharge or ESD) will damage your electronics. You are taking a great risk soldering your PCBAs in areas that are not ESD safe. If you do not have such area but are insistent on handling your radio's electronics, you can reduce the amount of charge your body is carrying by first discharging yourself at a grounded fixture such as the metal screw holding the electrical outlet faceplate, any non-painted metal device (or area on that device) that is plugged in an outlet with a grounded plug (usually a third non-current carrying terminal), wearing non ESD generating clothing, do not work in carpeted areas, do not roll your chair around while handling your electronics, etc. People do not realize that some of their devices fail later due to latent ESD failure because they opened and handled their devices in a non ESD safe area.

    2) Because these devices are manufactured so that they can be sold ROHS compliant to places like Europe, they use lead free solder. Lead free solder requires more heat to melt but the components themselves are not necessarily more tolerant to heat. These parts were intended to be solder with a specific reflow profile which is never repeatable with a soldering iron. A part can be damaged in less than 10 seconds of applied heat (especially if the soldering iron is above 600C). The fastest way to get solder to melt so that a part can be removed is by adding some flux to the component pad prior to applying the soldering iron. It helps if you have a temperature controlled soldering iron and the proper tips for component removal (I actually have channel tips to simulateously heatup all the IC pins, allowing me to remove, say a 20-pin SOIC part, in about 5 seconds without damaging pads).

    3) It is better to buy and use new 0603 resistors (100 ohms, 1000 ohms, etc.) ahead of the modifications than reusing heated parts. When you heat the parts the conductive ends may not be free of contaminates due to over heating. Also the pads must be cleaned prior to putting the part on the board (new or reused). Failure to do this may required excessive heat to get the part to solder to the board.

    4) I have seen some photos on this thread and I can clearly see that there are some cold solder joints, some joints were disturbed while cooling, some did not use flux when soldering, some have the wire strewn across other components (Wires carrying I2C can induce noise into circuits the wire is laying across--SCL is the clock line and can run at speeds of 100kHz, 400kHz and even 3.4MHz), etc. I also saw unsecured wire...the radio is in a vehicle that experiences vibration and shock (sudden jarring movement with energy transferred through the medium) so if the wire is not well secured it could break loose then that energized wire could short something out inside your radio.

    5) During PCB layout, not all traces go out from the chip. Sometimes I route under the chip, through the board onto an internal layer, etc. Thoses 'pads' that were identified as alternative pickup points for SCL and SCK, those are VIAs. On this board, they are coated with soldermask. If you try to heat that via to make a wire stick you will be applying heat for a long time and risk damaging the via. If you improperly scrap the solder mask you also risk damaging the via. If that via is damaged you can render the board unrepairable if that via happens to be going to an inner layer trace that you can not see nor access. Best to use the larger component pads.

    6) Invest in good wire...don't just grab any wire you have around as a poor choice can reshape the signal and make the circuit misbehave. The wire should not be any longer than necessary (I2C is very sensitive to noise).

    That's all for now.