XTRONS MTCD - Weak Bass - HW Audio MOD

[Twain0]

Hi all

Bought a XTRONS MTCD head unit for my Audi TT MK2 (PX5, PB76ATTARP, Android 6.0, Octa-Core, 2GB RAM) and paired it with active OEM system. The sound was over all extremely disappointing so I decided to upgrade my car with the Audi Plus sound system, being specifically designed by Alpine for the TT MK2. Sound still appeared thin and had been lacking very much of bass despite of strong 200mm bass drivers and 400W amp. All integrated equalizers (also Viper) did not help to give the system sufficient deeps.

Made some investigations and found the audio design in the XTRONS head unit to be a complete disaster. The cinch outputs are actually not capable to drive low impedance amp inputs such as present with the Alpine amp. The rather low impedances of the Alpine's inputs do interact with the output decoupling capacitors in the head units audio design giving a high pass effect with pretty high cut-off frequency (somewhere between 100 and 200 Hz! ).

Fortunately the cinch audio signals are extracted with an external breakout board including an audio buffer section. The affected four decoupling capacitors (C156-C159, next to output connector of board) can easily be replaced with larger capacitors without disassembling the head unit. Just cut open the shrink hose (keep it and reattach later with adhesive tape) and replace the capacitors with a thin solder iron. This step needs a certain degree of solder experience but will be provided for sure by service guys of local Radio/TV store if you do not want to take the challenge.

The original capacitors are SMD 0603 size and have capacity of 0.8...1uF. I replaced them with 0603 capacitors with 4.7uF and 10V voltage strength. You can get such parts from Ebay, Mouser, Conrad Electronic, Distrelec, Farnell and many other places.

Cannot show picture here since I'm new to the forum. But can send picture of the breakout board with affected capacitors marked.

After capacitor replacement the bass is now very present with deep and punchy lows. The difference before-after is like night-day Still wondering how these Chinese guys did mess up the audio design by saving 0.003 cent per head unit...

The measure might be applicable also to other/older head units such as PX3 and other Android head units. As I e.g. remember, the PX3 has also a weak audio design with no dedicated output buffers for cinch signals. There the signals are directly broken out between audio codec and amp section and the capacitors in those signal paths might also be too small to serve low impedance loads with deep bass.

BR
Twain

 

[eagle88123]

Hello,
Got same issue can you pls share the the pictures ? Pls email on [email protected]
Thank you.

 

[Oberbergler]

Hi,
thank you for your explanation. I've also weak bass. Could you please send me pictures of your work to [email protected]
Regards

 

[eagle88123]

Hi,
thank you for your explanation. I've also weak bass. Could you please send me pictures of your work to [email protected]
Regards

Just to confirm that I received the picture that you send.
Thank you very much.
Your the man!!

 

[crator1349]

Hi can you send to me as well? [email protected] or if someone who can post them please post?

 

[Twain0]

Hi,
thank you for your explanation. I've also weak bass. Could you please send me pictures of your work to [email protected]
Regards

Can you post the picture here?

Thanks

 

[Oberbergler]

Can you post the picture here?

Thanks

Sure

 

[Twain0]

Sure

Thanks!

 

[marchnz]

Note that standard MTCD coupling capacitors to preamp and RCA are 2.2uF, also to onboard TDA power AMP are 10uF.

Not sure what your unit is from the image provided, looks like an additional signal board.

Requested MOD move this thread to correct MTCD Hardware section.

 

[ab1702]

Hi all

Bought a XTRONS MTCD head unit for my Audi TT MK2 (PX5, PB76ATTARP, Android 6.0, Octa-Core, 2GB RAM) and paired it with active OEM system. The sound was over all extremely disappointing so I decided to upgrade my car with the Audi Plus sound system, being specifically designed by Alpine for the TT MK2. Sound still appeared thin and had been lacking very much of bass despite of strong 200mm bass drivers and 400W amp. All integrated equalizers (also Viper) did not help to give the system sufficient deeps.

Made some investigations and found the audio design in the XTRONS head unit to be a complete disaster. The cinch outputs are actually not capable to drive low impedance amp inputs such as present with the Alpine amp. The rather low impedances of the Alpine's inputs do interact with the output decoupling capacitors in the head units audio design giving a high pass effect with pretty high cut-off frequency (somewhere between 100 and 200 Hz! ).

Fortunately the cinch audio signals are extracted with an external breakout board including an audio buffer section. The affected four decoupling capacitors (C156-C159, next to output connector of board) can easily be replaced with larger capacitors without disassembling the head unit. Just cut open the shrink hose (keep it and reattach later with adhesive tape) and replace the capacitors with a thin solder iron. This step needs a certain degree of solder experience but will be provided for sure by service guys of local Radio/TV store if you do not want to take the challenge.

The original capacitors are SMD 0603 size and have capacity of 0.8...1uF. I replaced them with 0603 capacitors with 4.7uF and 10V voltage strength. You can get such parts from Ebay, Mouser, Conrad Electronic, Distrelec, Farnell and many other places.

Cannot show picture here since I'm new to the forum. But can send picture of the breakout board with affected capacitors marked.

After capacitor replacement the bass is now very present with deep and punchy lows. The difference before-after is like night-day Still wondering how these Chinese guys did mess up the audio design by saving 0.003 cent per head unit...

The measure might be applicable also to other/older head units such as PX3 and other Android head units. As I e.g. remember, the PX3 has also a weak audio design with no dedicated output buffers for cinch signals. There the signals are directly broken out between audio codec and amp section and the capacitors in those signal paths might also be too small to serve low impedance loads with deep bass.

BR
Twain

Is this item that is now pictured the one that is attached to the 4 audio cables inside some black heatshrink with a connector on it?
If so I’ll be doing this mod as I have put my Audi concert radio back in at the moment while my xtrons is being repaired and I can tell the difference straight away even though I thought the sound with my xtrons(GS) unit was decent.

Thankyou for figuring this out

 

[homer.ali]

Bump! Interested in the answer to the question above!

 

[lysaer]

Hi all

Bought a XTRONS MTCD head unit for my Audi TT MK2 (PX5, PB76ATTARP, Android 6.0, Octa-Core, 2GB RAM) and paired it with active OEM system. The sound was over all extremely disappointing so I decided to upgrade my car with the Audi Plus sound system, being specifically designed by Alpine for the TT MK2. Sound still appeared thin and had been lacking very much of bass despite of strong 200mm bass drivers and 400W amp. All integrated equalizers (also Viper) did not help to give the system sufficient deeps.

Made some investigations and found the audio design in the XTRONS head unit to be a complete disaster. The cinch outputs are actually not capable to drive low impedance amp inputs such as present with the Alpine amp. The rather low impedances of the Alpine's inputs do interact with the output decoupling capacitors in the head units audio design giving a high pass effect with pretty high cut-off frequency (somewhere between 100 and 200 Hz! ).

Fortunately the cinch audio signals are extracted with an external breakout board including an audio buffer section. The affected four decoupling capacitors (C156-C159, next to output connector of board) can easily be replaced with larger capacitors without disassembling the head unit. Just cut open the shrink hose (keep it and reattach later with adhesive tape) and replace the capacitors with a thin solder iron. This step needs a certain degree of solder experience but will be provided for sure by service guys of local Radio/TV store if you do not want to take the challenge.

The original capacitors are SMD 0603 size and have capacity of 0.8...1uF. I replaced them with 0603 capacitors with 4.7uF and 10V voltage strength. You can get such parts from Ebay, Mouser, Conrad Electronic, Distrelec, Farnell and many other places.

Cannot show picture here since I'm new to the forum. But can send picture of the breakout board with affected capacitors marked.

After capacitor replacement the bass is now very present with deep and punchy lows. The difference before-after is like night-day Still wondering how these Chinese guys did mess up the audio design by saving 0.003 cent per head unit...

The measure might be applicable also to other/older head units such as PX3 and other Android head units. As I e.g. remember, the PX3 has also a weak audio design with no dedicated output buffers for cinch signals. There the signals are directly broken out between audio codec and amp section and the capacitors in those signal paths might also be too small to serve low impedance loads with deep bass.

BR
Twain

I have a joying unit currently and was looking at upgrading to an Xtrons but am worried I might suffer the same issue

do you know the width of the capacitors you purchased, was looking at these

https://www.mouser.co.uk/Passive-Co...Z1yx4aw4Z1yzmou6Z1y95kco&Keyword=0603&FS=True

 

[dj-clark]

Xtrons PX5 have much better sound quality than Joying unis... I had Joying and now have Xtrons... Much better bass output and overal quality.

I have a joying unit currently and was looking at upgrading to an Xtrons but am worried I might suffer the same issue

do you know the width of the capacitors you purchased, was looking at these

https://www.mouser.co.uk/Passive-Co...Z1yx4aw4Z1yzmou6Z1y95kco&Keyword=0603&FS=True

 

[lysaer]

Xtrons PX5 have much better sound quality than Joying unis... I had Joying and now have Xtrons... Much better bass output and overal quality.

It does seem though that the original poster still suffered this weak bass issue with an Xtrons PX5 unit

 

[Hyundai2005]

Thanks

 

[typos1]

Hi all

Bought a XTRONS MTCD head unit for my Audi TT MK2 (PX5, PB76ATTARP, Android 6.0, Octa-Core, 2GB RAM) and paired it with active OEM system. The sound was over all extremely disappointing so I decided to upgrade my car with the Audi Plus sound system, being specifically designed by Alpine for the TT MK2. Sound still appeared thin and had been lacking very much of bass despite of strong 200mm bass drivers and 400W amp. All integrated equalizers (also Viper) did not help to give the system sufficient deeps.

Made some investigations and found the audio design in the XTRONS head unit to be a complete disaster. The cinch outputs are actually not capable to drive low impedance amp inputs such as present with the Alpine amp. The rather low impedances of the Alpine's inputs do interact with the output decoupling capacitors in the head units audio design giving a high pass effect with pretty high cut-off frequency (somewhere between 100 and 200 Hz! ).

Fortunately the cinch audio signals are extracted with an external breakout board including an audio buffer section. The affected four decoupling capacitors (C156-C159, next to output connector of board) can easily be replaced with larger capacitors without disassembling the head unit. Just cut open the shrink hose (keep it and reattach later with adhesive tape) and replace the capacitors with a thin solder iron. This step needs a certain degree of solder experience but will be provided for sure by service guys of local Radio/TV store if you do not want to take the challenge.

The original capacitors are SMD 0603 size and have capacity of 0.8...1uF. I replaced them with 0603 capacitors with 4.7uF and 10V voltage strength. You can get such parts from Ebay, Mouser, Conrad Electronic, Distrelec, Farnell and many other places.

Cannot show picture here since I'm new to the forum. But can send picture of the breakout board with affected capacitors marked.

After capacitor replacement the bass is now very present with deep and punchy lows. The difference before-after is like night-day Still wondering how these Chinese guys did mess up the audio design by saving 0.003 cent per head unit...

The measure might be applicable also to other/older head units such as PX3 and other Android head units. As I e.g. remember, the PX3 has also a weak audio design with no dedicated output buffers for cinch signals. There the signals are directly broken out between audio codec and amp section and the capacitors in those signal paths might also be too small to serve low impedance loads with deep bass.

BR
Twain

Interesting, always found MTCB/C and MTCD/E units to have too low a signal on the RCA connectors to properly drive my factory Bose amp, although 7floor's mod overcomes this. MTCD PX3 units wont be any different as they simply have a different processor board, everything else is the same..

Note that standard MTCD coupling capacitors to preamp and RCA are 2.2uF, also to onboard TDA power AMP are 10uF.

Not sure what your unit is from the image provided, looks like an additional signal board.

Requested MOD move this thread to correct MTCD Hardware section.

He said "Xtrons" so I guess he has a GS unit.

 

[Twain0]

Hi there

Yes, its the pcb in the heatshrink, sitting outside the actual head unit.
And again, the sound improvement has been REALLY obvious after the mod. At least with my setup.

Sold the car meanwhile so the topic went out of focus a litte.

BR

 

[bossman4]

Hi there

Yes, its the pcb in the heatshrink, sitting outside the actual head unit.
And again, the sound improvement has been REALLY obvious after the mod. At least with my setup.

Sold the car meanwhile so the topic went out of focus a litte.

BR

I sent back my XTRONS unit when it died. Before it died, I was having a hard time before it quit to match levels with my OEM Bose amp unit in my Mazda Miata. Everybody that does a workaround on the replacement by using the speaker outputs of the new head unit rather than the RCA outputs utilizing a device like SCOOSCHE SLC-4. I am looking at another unit now from EONON that has a DSP chip in it. I asked the EONON folks the question about the line output levels. Here was their answer below.

Dear Customer,

Nice day.
Thank you for your interest in our products, pls kindly refer to the specification below:
1. The pre-amp voltage of GA2171S is: 2.0Vrms±0.2V
2. RCA audio output voltage: 2.0Vrms ± 0.2V
3. Other audio output voltages such as subwoofer are: 1.5Vrms±0.2V
4. The resistance value of audio output / (horn resistance value): 4Ω
5. Signal to noise ratio: ≥-65DB


I am not sure how to interpret this apparent good news (2.0Vrms±0.2V) with questions like balanced and unbalanced inputs. Sound like the replaced BOSE head unit has unbalanced outputs. Not sure how that affects these specifications..

 

[typos1]

I sent back my XTRONS unit when it died. Before it died, I was having a hard time before it quit to match levels with my OEM Bose amp unit in my Mazda Miata. Everybody that does a workaround on the replacement by using the speaker outputs of the new head unit rather than the RCA outputs utilizing a device like SCOOSCHE SLC-4. I am looking at another unit now from EONON that has a DSP chip in it. I asked the EONON folks the question about the line output levels. Here was their answer below.

Dear Customer,

Nice day.
Thank you for your interest in our products, pls kindly refer to the specification below:
1. The pre-amp voltage of GA2171S is: 2.0Vrms±0.2V
2. RCA audio output voltage: 2.0Vrms ± 0.2V
3. Other audio output voltages such as subwoofer are: 1.5Vrms±0.2V
4. The resistance value of audio output / (horn resistance value): 4Ω
5. Signal to noise ratio: ≥-65DB


I am not sure how to interpret this apparent good news (2.0Vrms±0.2V) with questions like balanced and unbalanced inputs. Sound like the replaced BOSE head unit has unbalanced outputs. Not sure how that affects these specifications..

All MTCB/C/D/E headunits have that sort of voltage on the RCAs, this wasnt enough for my Bose system that like yours uses the speaker wires, but I did @7floor's sound mod on my MTCC unit and the pre amp function sorted the problem , I m about to do @Wadzio's audio mod (same as 7floor's but via software) which also has a pre amp setting, cant say if the DSP unit will be better but see these 2 threads :


https://forum.xda-developers.com/and...tcd-e-t3823075

https://forum.xda-developers.com/and...p-com-t3803557

and general audio improvement discussion here :

https://forum.xda-developers.com/an...d-e-sound-improvement-options-advice-t3849317

 

[rroblesleal]

PX3

Hi, I have the Audi A3 PX3 headunit from Xtrons. Does this also works with that unit? Also the capacitors, whats the difference between the 4.7UF and the 10UF? I really don’t know anything about capacitors so I don’t know which one to choose. I have the Bose sound system and It also has really weak bass.
Thank you!