Have you considered onboard regulation!? The amplifiers do benefit from linear PSUs. Tried that again last weekend.
Also the more film caps where they matter the better it is. Same goes for oversized filter coils.
I'm. But if i agree - i will have only 10pcs, coast ~25$
This is too much. I need only one board
Do u tried to use film caps around MA12070P? I think this can improve quality of integrated DAC
I think need to use two quality LC filters between the output of PSU and the amplifier board
Are you using two PWM PSU 24V and 5V? Show your power supply and can u recommend something good quality from Ali?
"Good quality from Ali"
If u want to use full linear PSU - try to put 5V line to new PCB layer. I think there need to use 4 layer PCB for EMI shield 5V power line where 3-d layer is shield and bottom layer is 5V line
I found arduino sketch that have:
1. Transfer to I2S mode - standard.
2. Profile switching.
3. Volume control with a potentiometer connected to the arduino.
https://forum.vegalab.ru/showthread.php?t=92780&page=2
ma12070p-2.zip
Someone write scetch for volume control by encoder?
I have a very quiet LDO for the 5v circuit, where it supplies the DAC. The rest of the amp depends on what you feed it. Only issue with the LDO is the narrow operating voltage of 5.5-6v required. So I step it down from the main 26v supply using a high frequency buck converter (1mhz)
Yes, definitely. The analog input and all outputs have spaces for PTH film caps. I've also been using some Panasonic Polyphenylene Sulfide (PPS) film SMD capacitors. Supposedly has a very low distortion. But probably can't hear the difference because supposed to be filtering RFI not audio.
My coils are quite oversized at 30A, but they look tiny because they are only 1.5uH.
I was thinking of that, but film caps are useful only for the DAC output filters. On the MA12070, there are no external DAC output filters, everything is internally connected DAC > AMP, so just followed the datasheet specs.
Most caps around the MA12070 are for flyback and decoupling. Also reading the datasheet, all these happen at very high frequencies. Inductance of the PCB trace (closer the better) and capacitor inductance need to be considered.
Since film caps have much higher inductance than MLCCs and larger so the PCB traces need to be 2x-3x longer than MLCCs, I again just stuck to the recommended components (Murata X7R) and layout.
I have used film caps where I can, for all the analog output filters
Last edited:
I got my hands on used medical grade 26v supplies. They change them every 2 years as part of routine maintenance for life support machines. Huge caps and LC filters. Ripple was almost at the limit on what my scope could measure.
But it's the LC filter at the output that made the difference. I have not measured the value of the inductor, but large toroidal coils plus caps. You can see what inductor you can get your hands on and sim it to find the capacitance value quite easily.
Yes, I have made 4 pairs of the digital version and they all work nicely. Just about the make the analog version
I'm just tweaking my design for easier manufacturing (I have a few SMD components which are too close together), and breaking out the pins so you can select the i2c address
Oh you will hear it when RF gets filtered out more.
An assumption, try them out at spots and then in the smallest physical 50V versions. At inputs they clearly make a difference. At various spots one can not do without ceramic SMD caps. Anyway, avoid X5R and such. Just have 100V X7R as minimum standard in the larger formats. I had a few MA12070 amplifiers where the 50V caps made whining noises.
The one spot where you definitely can not use film or TH caps is the flyback caps.
Last edited:
So impossible to add headphones output?
Some guys recommend to use EPCOS NP01 ceramic caps, they say that they suppress interference
I tried to get the China digital in version to run with Patricks Attiny Code. I get really distorted sound but I can hear voice with right pich within the distortion. Would I get the right pich from voice if the right Format was not active?
May be that my Bluetooth I2S board is to close to the amp. After all it is a switching amp.
Any ideas to solve my issue are welcome
Klaus
May be that my Bluetooth I2S board is to close to the amp. After all it is a switching amp.
Any ideas to solve my issue are welcome
Klaus
It would help to be clear and to add pictures.
1. What is the China digital version? They all come from China.
2. If that Patrick had it running the code seems OK and you introduced another variable.
3. Which Bluetooth I2S board?
4. How long are the connection wires between boards for I2S? Less than 20 mm is optimal.
1. What is the China digital version? They all come from China.
2. If that Patrick had it running the code seems OK and you introduced another variable.
3. Which Bluetooth I2S board?
4. How long are the connection wires between boards for I2S? Less than 20 mm is optimal.
My experience with feeding standard i2s into the MA12070 at default setting (LJ i2s) is soft but SLIGHTLY distorted sound. If it's loud and very distorted, there could be other issues.
There are other settings such as master clock and framesize frequencies that you need to get synced before it works. I don't know what your Bluetooth board outputs, but it can be easily checked with a multimeter with a frequency function. Here are the outputs from my Raspberry Pi:
LRCLK / WS: 44.1khz
BCLK / SCK: 2.822 Mhz
This means my i2s framesize is 64 bits per sample (2,822khz/44.1Khz). This is the default framesize of the MA12070. If you have any other ratio, then you need to set it accordingly. Bit 3&4 of register 0x36. See p.78 of the datasheet. Let me know if you need help on this.
The master clock frequency also needs to be in sync with the i2s inputs and correspond to the frequencies on p. 23 of the datasheet. On my board, I tied the BCLK to MCLK so it is at 2.822 Mhz which is listed in the datasheet.
I don't know how the Chinese board implements the MCLK input, but I suspect it's tied to the BCLK as well.
Patrick
There are other settings such as master clock and framesize frequencies that you need to get synced before it works. I don't know what your Bluetooth board outputs, but it can be easily checked with a multimeter with a frequency function. Here are the outputs from my Raspberry Pi:
LRCLK / WS: 44.1khz
BCLK / SCK: 2.822 Mhz
This means my i2s framesize is 64 bits per sample (2,822khz/44.1Khz). This is the default framesize of the MA12070. If you have any other ratio, then you need to set it accordingly. Bit 3&4 of register 0x36. See p.78 of the datasheet. Let me know if you need help on this.
The master clock frequency also needs to be in sync with the i2s inputs and correspond to the frequencies on p. 23 of the datasheet. On my board, I tied the BCLK to MCLK so it is at 2.822 Mhz which is listed in the datasheet.
I don't know how the Chinese board implements the MCLK input, but I suspect it's tied to the BCLK as well.
Patrick