Very interested in your progress. Trying to get this board to work off an ESP32 board. Have you followed the alsamixer settings procedure in the HAT manual? Maybe some threshold is exceeded?
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d4626eab8fbf016eef8084096be6
Mike
An externally hosted image should be here but it was not working when we last tested it.
Removal of the 0805 input caps enable a lot of more spatiality and air into the music. The input transformer is used to take the SE inputs and provide a differential signal for the amp module inputs. I now believe the caps on the board is a bottleneck.
Thanks to the tweak mentioned by Toku, the turn on pop has reduced to a very small click and power down is noiseless.
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Mmm, loss of galvanic separation then. Why the GND connection? I also assume (yes, dangerous) from experience that connecting the middle pin of the secondary to GND is not liked by the inputs if they have a DC potential.... In issue that would not occur if one just connects just the secondary to both input pins.....as both normally carry the same DC potential....
Again, all assumptions based on other chips. I might be completely wrong although I don't think so.
Again, all assumptions based on other chips. I might be completely wrong although I don't think so.
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Thank you for that reminder! I was using DietPi, which doesn't ship with the Merus drivers and overlays (even though it's based on Raspberry OS, which does ship with those). So I went ahead and booted up Raspberry OS, and am now using the official drivers (per the documentation you linked).
So far it works exactly the same as before, except that I can use the Alsa tools (e.g. alsamixer) to control volume and other parameters. Before I was doing that via manual I2C programming. So if nothing else, this is much more convenient.
However, the hiss remains, no matter what I do in the Alsa controls. Thinking maybe there was some "magic" in the official Merus drivers, I again tried using the MCLK from the Kali for the ma12070p, but I get no playback when I do that (although it does get rid of the hiss).
Now I'm thinking about trying one of those Chinese ma12070(p) boards that many in this thread have. Looks like they now offer analog or digital input. So I could grab the digital input version and see if that makes any difference.
Edit: DietPi does in fact ship with the Merus drivers. Looks like I was working off what appears to be a botched upgrade.
I used to have an Amanero, which would be good for testing another I2S source. But now I can't find it!
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Bummer! I had the board working using piCorePlayer, which now has the Merus drivers. I'll hook it up again. I don't remember any hiss, but then again my tinnitus may have masked it. I'll have my wife do the listening test.
I'm having a hard time using the MA12070 board on Aliexpress.
The balanced connection works perfectly fine, but with an unbalanced input connection that connects IN0B and IN1B to GND, connecting a volume or terminating with a 10kΩ or 3.3kΩ resistor does not improve the noise problem. .. When nothing is connected to the input, it makes a lot of noise and cannot be used.
So I checked some MA12070 amplifiers and connected the OP amplifier preamplifier to the input, and stable operation was obtained. However, when the power is turned off, pop noise will be newly generated from the preamplifier, and it is necessary to consider countermeasures for this.
I think it would be better to have a balanced connection with the MA12070 as the preamp to add, but unfortunately I couldn't find a preamp that would convert to unbalanced >> balanced. There seems to be no choice but to make it yourself.
Another improvement is to use the input transformer you have proposed. This is the most reliable method of unbalance-balance conversion. I used to use it all the time in the design of professional equipment. Recently, I have become accustomed to pseudo-balanced circuits using semiconductor circuits and forgot about the existence of input transformers. There are some good transformers I used in the past, so I would like to try them.
It is difficult to master the amplifier board using this MA12070.
I've read the datasheet over and over again, but am I overlooking something?
Hello Toku,
I've been reading this forum for a long time and learned a lot.
My English is quite bad, but luckily we can find a good translator.
I am using a 3eaudio 3255 revB card and a DAC E30 from topping.
I use now an unbalanced to balanced converter with.
I take the +12v directly on the 3eaudio card.
this card works wonderfully and is inexpensive(improved dynamics and bass)
DRV134 carte desequilibree a equilibree alimentation unique entree differentielle carte amplificateur de puissance double canal sortie BTL | AliExpress
The seller delivers fairly quickly (12 days for France).
Good continuation in your research
I've been reading this forum for a long time and learned a lot.
My English is quite bad, but luckily we can find a good translator.
I am using a 3eaudio 3255 revB card and a DAC E30 from topping.
I use now an unbalanced to balanced converter with.
I take the +12v directly on the 3eaudio card.
this card works wonderfully and is inexpensive(improved dynamics and bass)
DRV134 carte desequilibree a equilibree alimentation unique entree differentielle carte amplificateur de puissance double canal sortie BTL | AliExpress
The seller delivers fairly quickly (12 days for France).
Good continuation in your research
I found my Amanero. Did a couple more tests:
That would be interesting! Do you have the exact same board, the reference PCB from Infineon?
- Put the Amanero between the RPI and the ma12070p. Using the Amanero's MCLK with the ma12070p had the same result as with the Kali: no sound. So once again I didn't use the source MCLK, and jumpered BCLK and MCLK on the ma12070p board. In this config, playback works, but there is the ever-present hiss coming from the PCB itself.
- I used our laptop (running on battery) to power the Amanero. Interestingly, in this configuration I could get playback using the Amanero's MCLK connected to the ma12070p. I did have to temporarily connect the RPI just to send the I2C commands to the amp board to use right-justified I2S (I don't currently have a way to do I2C via the laptop). But after that, I removed power from the RPI. Playback works as expected, but the ma12070p board still hisses.
That would be interesting! Do you have the exact same board, the reference PCB from Infineon?
The exact same board. I did find small terminal blocks to solder to the board, which makes speaker connections MUCH easier. Had trouble until I realized I had D.Lim set at -40db.
Anyway, I just borrowed my wife's ears and she, too, could not here any hiss.
I have the ref board powered by a 12 volt battery.
I just noticed from your picture that the ground pins on the ref board are floating. Mine are connected to the ground GPIO pins on the Rpi. Could that be the problem?
Mike
Thank you for your advice.
I'm obsessed with the appeal of cheap class D amps made in China and have bought and tested over 30 amp products so far. The 3 audio amplifier products you recommended are 260W 2Ch (Ver1 & Ver2) and 480W 1Ch models purchased and in use. Recently, I also got an additional finished amplifier. All 3e audio amp board products are great.
Recently I was very interested in the MA12070 chip when I heard the sound of the SMSL SA300. I bought 4 MA12070 amp boards from Aliexpress and am currently testing them. However, this chip is very difficult to obtain stable operation unlike the conventional amplifier board products. I think I'm missing some knowledge information.
you can use 3e audio dsp adau1701 which has balanced output and you can take advantage of the dsp and a high performance from analog device IC. Even you can use sigma estudio to enable some filters.
Interesting. How did you connect MCLK on the ref board?
Since taking that initial picture, I have connected the ground pins on the reference board (to the GPIO pins of the RPI). I've tried all four combinations of those two GND pins connected/floating, and it doesn't seem to change anything.
I made my own Y splitter, giving me a female to two female jumper,
connecting the one side to the Pi's BCLK and the other two to the eval board's BCLK and MCLK.
I wonder if this results in a better voltage split to the eval board than the way you jumpered the two?
I connected the CT pins of the trafos to GND via an electrolytic cap as the DC potential isn't 0V. I used 2700uF/6.3V
Here's a pic of how I wired up the AVDD caps - bit of a gash job I must admit. There are polymer caps close to the IC (for low ESR) and those bulky Panasonic 15000uFs further away.
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