Infineon MA12070 Class D

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#781
Just read that document by Infineon and some filter theory to see why "coils only" is not the right way. If one does not want to bother the 4 x BLE32PN300SN1L ferrite beads and 2 x 1 nF MKS/MKT are minimal protection. Any choice for coils will be more complex and time consuming certainly when not follows the recommendations of Infineon. No filtering or practically no way to add filtering in a ready made product is a no go for me.

Hence the search for MA12070 devices that do have the minimum of necessary bells and whistles so I made a small list of criteria. 1 to 4 are absolutely necessary IMHO to weed out the real bad ones, 5 and 6 are nice to haves:

1. Either beads or coils and caps or the PCB pads to replace/add those.
2. Decent way of converting unbalanced to balanced as it is a necessity for MA12070 to perform OK.
3. PCB layout as recommended by Infineon.
4. Possibility to replace class III input ceramic caps to X7R ones/film caps/wires.
5. Possibility to replace class III decoupling caps to X7R/film ones.
6. Possibility to replace the class III "flying" capacitors for X7R/film ones.

The impression is that Chi-Fi manufacturers of the cheapest products just use parts that resemble what should be used (and no one complains anyway). Specifically the class III caps are the cheapest one can find and also the worst available. Maybe it is better not to know 🙂 The chip must therefor do something really well in such an environment of cheapness.
 
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#783
On the Ayima a few of the bank of ceramics after the chip are certainly part of the Filter although I can not see any traces going to the coils. Propably 4 layer design
 

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#784
No caps after the coils (LC remember?) which is left on your picture. They could be added using the L+ and L-, R+ and R- pads when one knows the properties of the coils. If one wishes to do stuff right that involves measuring the coils, recalculation, remeasuring etc. The Aiyima exhibits a loud whine after switching it on. Still have to find out why that is. Not over the loudspeakers but through its casing.

https://electronicbase.net/low-pass-filter-calculator/

BTW an extra criterium could be:

7. Decent way of creating a low noise 5V for DVDD.
 
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#786
You won't as it does not exist as explained in 1 sentence. I am used to having stuff produced but in this case the costs are IMO not worth the trouble when comparing.

For instance: I paid 60 Euro for the Aiyima A8, power supply and shipping included. No way I can make even a PCB with parts for that price. If being done then choices for SMPS and other costcutting stuff also comes into play and the design will be a 1 day fly with main feature MA12070 like Chi-Fi devices. For an overall good quality design it will simply be not economically viable. Of course I am not so strict in the economical teachings as I use expensive transformers and linear power supplies as standard but that is audio and the forthcoming desire to raise the bar with regards to quality. This module seemed a good combination of factors and it easily integrates according design requirements:

https://www.audiophonics.fr/en/ampl...lifier-module-ma12070-160w-4-ohm-p-14732.html
 
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#791
DIY is for me not about economics. It is about making my own choices for components and layout. If i would design a MA12070 board. I use XLR/Jack no caps in. And rest X7R caps. Good filter out. It is not so difficult and expensive. Total cost about €20
 
#793
Koifarm said:
DIY is for me not about economics. It is about making my own choices for components and layout. If i would design a MA12070 board. I use XLR/Jack no caps in. And rest X7R caps. Good filter out. It is not so difficult and expensive. Total cost about €20
Click to expand...
For me it is about price/quality ratio with emphasis on the latter item so no SMPS for instance. I would like to see that design when it really costs 20 Euro. A quality design in all aspects with best parts for the purpose, no gadget like device. The nice thing of Chi-Fi is that many only got to know this chip because of the cheap gadget devices that lack a necessary feature here and there 😀. Only the power transformer for a decent design cost me 25 Euro today and this was a 50% discount transformer. Normally it would be 50 Euro and then one needs to add costs for rectifiers/filter cap/regulator/heatsink to that. Casing cost is also relatively high nowadays.

Radian said:
Mmmm, .3 ohms from Cap c20 to output of coil L3 .
Unless the damaged chip plays a roll here we have a filter
Click to expand...
Rethink that one 🙂

Nesha, do you have a link? Seems they knew how to design a device.
 
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#797
jean-paul said:
For me it is about price/quality ratio with emphasis on the latter item so no SMPS for instance. I would like to see that design when it really costs 20 Euro. A quality design in all aspects with best parts for the purpose, no gadget like device. The nice thing of Chi-Fi is that many only got to know this chip because of the cheap gadget devices that lack a necessary feature here and there 😀. Only the power transformer for a decent design cost me 25 Euro today and this was a 50% discount transformer. Normally it would be 50 Euro and then one needs to add costs for rectifiers/filter cap/regulator/heatsink to that. Casing cost is also relatively high nowadays.


Rethink that one 🙂

Nesha, do you have a link? Seems they knew how to design a device.
Click to expand...
Aliexpres, but i have problem to pass a link ???🤔
 
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