I don't understand this questions to be honest.
The measurements are already for BTL configuration (standard Stereo-operation).
And no, you cannot set the power-mode profile per output. You can configure it via I2C, but the power-mode profile applies for the whole amp (and therefore also all outputs).
MA120x0 doesn't have stability problems in open-load condition in proposed ferrite-bead filter configuration.
Hi Toku,
what you describe is relatively typical for amplifier-boards where the input is not terminated and just having "open-connection".
A good design should always have a termination.
A 10kOhm between signal-input to GND should be fine.
I will try to be clearer. Let's say I want to connect the 4 channels separately (4.0), my question is if the distortion of the 2 nd and 3 rd channel is lower than 1 and 4?
Attachments
Hi,
Do the Eval board from infineon worth a try?
Seem expansive
https://www.infineon.com/cms/de/product/evaluation-boards/eval_audio_ma12070p/
Do the Eval board from infineon worth a try?
Seem expansive
https://www.infineon.com/cms/de/product/evaluation-boards/eval_audio_ma12070p/
The evalboard makes only sense in my opinion if you want to design an own PCB with the MA120x0 devices.
The best thing about it is that you have an USB-I2C converter on board and you can control all the internal settings with a computer based UI software.
You can see this here in slide 6+7
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d46269e1c019016ac02913fd32dc
Thanks...I just want to taste it ;-)
Any advice for a P board?
Or p based amp like smsl?
We tested the addition of an input VR and the addition of a preamplifier to eliminate noise during unbalanced connection of the MA12070 amplifier board.
I bought the following input VR and preamp board used for the test.
RK16 50KΩA
AIYIMA 1 ピースを 50 k 100 k ALPS ポテンショメータ RK16 ダブル 6 ピンボリュームポテンショメータ PCB ボードと XH2.54|alps rk16|board boardboard pcb - AliExpress
AIYIMA NE5532 Op Amp Preamplifier Board
AIYIMA NE5532 Op Amp Preamplifier Board With Volume Potentiometer Single Power Supply|preamplifier board|board ampne5532 preamplifier board - AliExpress
With the addition of the input VR, the noise when the input is open has disappeared, but when the volume is turned, a different noise than before has come out. The largest noise is generated at the intermediate position. I have experienced the same symptoms with my LOX JIE A10 power amp.
The addition of the preamplifier solved the noise problem. At the same time, this can compensate for the gain that was insufficient with the amplifier board alone.
However, the pop noise when the power is turned on / off now comes out from the preamplifier board. However, it is acceptable because it is not so loud pop noise. The power supply of the preamplifier is connected in parallel to the power supply terminal of the amplifier.
I expected the easiest way to solve the noise problem by adding a terminating resistor to the input terminal or adding an input VR. But these methods didn't solve the noise problem.
I thought it would be impossible to eliminate the noise without adding a buffer amplifier to the input.
I bought the following input VR and preamp board used for the test.
RK16 50KΩA
AIYIMA 1 ピースを 50 k 100 k ALPS ポテンショメータ RK16 ダブル 6 ピンボリュームポテンショメータ PCB ボードと XH2.54|alps rk16|board boardboard pcb - AliExpress
AIYIMA NE5532 Op Amp Preamplifier Board
AIYIMA NE5532 Op Amp Preamplifier Board With Volume Potentiometer Single Power Supply|preamplifier board|board ampne5532 preamplifier board - AliExpress
With the addition of the input VR, the noise when the input is open has disappeared, but when the volume is turned, a different noise than before has come out. The largest noise is generated at the intermediate position. I have experienced the same symptoms with my LOX JIE A10 power amp.
The addition of the preamplifier solved the noise problem. At the same time, this can compensate for the gain that was insufficient with the amplifier board alone.
However, the pop noise when the power is turned on / off now comes out from the preamplifier board. However, it is acceptable because it is not so loud pop noise. The power supply of the preamplifier is connected in parallel to the power supply terminal of the amplifier.
I expected the easiest way to solve the noise problem by adding a terminating resistor to the input terminal or adding an input VR. But these methods didn't solve the noise problem.
I thought it would be impossible to eliminate the noise without adding a buffer amplifier to the input.
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@Toku:input impedance of MA12070 is 9.2 kOhm (and 2.2 µf input cap) in high gain mode and 15.3 kOhm (and 1 µF input cap) in low gain mode. I think the 50 kOhm volumecontrol is too high in impedance. Low gain is 19.5 and high gain is 25.2 dB.
So if the gain is not enough in low gain mode one could change to high gain mode, use a 10 kOhm volume potentiometer with a 2.2 kOhm series resistor and cap to GND (input RC filter to prevent pickup of RF/HF). The point is that I can not find how to change from low to high gain and vice versa
10 kOhm input impedance is not problem for a modern source.
BTW here is how Infineon uses a buffer to the MA12070:
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d46272e49d2a017351e1abf55966
So if the gain is not enough in low gain mode one could change to high gain mode, use a 10 kOhm volume potentiometer with a 2.2 kOhm series resistor and cap to GND (input RC filter to prevent pickup of RF/HF). The point is that I can not find how to change from low to high gain and vice versa
10 kOhm input impedance is not problem for a modern source. BTW here is how Infineon uses a buffer to the MA12070:
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d46272e49d2a017351e1abf55966
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BTW: Checkout those YouTube Video: MA12070P in the Marshall StockWell II
Marshall Stockwell II Teardown l Inside - Nội thất tệ qua ?? - YouTube
PCB teardown starts at 9:17
And Teardown of the SOUNDBOKS
??? ?????? ? ??????? ?? 75.530 ?????? Soundboks 2 (850 euro) - YouTube
MA12070P can be seen 3:41
Marshall Stockwell II Teardown l Inside - Nội thất tệ qua ?? - YouTube
PCB teardown starts at 9:17
And Teardown of the SOUNDBOKS
??? ?????? ? ??????? ?? 75.530 ?????? Soundboks 2 (850 euro) - YouTube
MA12070P can be seen 3:41
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Thanks for the advice on noise issues with unbalanced connections on the MA12070 amplifier board.
But none of them solved the problem. I terminated the input with 10kΩ, but there are new noise and distortion issues. The input circuit of Infineon's MONO amplifier is a balanced input and is not helpful.
I'm having a hard time understanding why unbalanced connections make noise when balanced connections are perfectly fine.
I checked the finished amplifiers on the market, but all of them have the preamplifier of the OP amplifier connected to the input.
When I connect a preamplifier board equipped with two types of OP amplifiers purchased from Ali EXpress's Aiyima Technology Store with reference to them, new pop noise is generated when the power is turned on and off, but it works very smoothly.
The operation of this amplifier board can be set via the I2C interface, but it is necessary to install programming software on the USB-I2C connection unit and PC. The setting parameters are explained in the manual, but learning and time are required to master them.
But none of them solved the problem. I terminated the input with 10kΩ, but there are new noise and distortion issues. The input circuit of Infineon's MONO amplifier is a balanced input and is not helpful.
I'm having a hard time understanding why unbalanced connections make noise when balanced connections are perfectly fine.
I checked the finished amplifiers on the market, but all of them have the preamplifier of the OP amplifier connected to the input.
When I connect a preamplifier board equipped with two types of OP amplifiers purchased from Ali EXpress's Aiyima Technology Store with reference to them, new pop noise is generated when the power is turned on and off, but it works very smoothly.
The operation of this amplifier board can be set via the I2C interface, but it is necessary to install programming software on the USB-I2C connection unit and PC. The setting parameters are explained in the manual, but learning and time are required to master them.
The chip has balanced inputs by definition. Balanced is lower noise also by definition, this is one of the very reasons the topology exists Noise is cancelled by design, please look that up as it goes too far to explain here. I think (my board is still unused) that an input RC filter is needed anyway when used unbalanced. This is standard practice with sensitive devices.
The reason others use active preamps/buffers is the low input impedance of MA12070. That is then solved. The opamp stage also has very low output impedance preventing issues like pickup of signals. Your power on/off phenomenons should be solved by design with a muting relay shorting the outputs to GND at power on/off. For some reasons (cost probably) these are omitted nowadays but they bring great joy.
The question is what kind of noise and distortion occur unbalanced. Is it pickup of signals, is it 50 Hz from mains voltage ?
* The circuit of the MONO Infineon amplifier is helpful. Please look more careful. It converts SE to balanced input. Repeat that for the second channel (not connected in that schematic) and issues are gone.
Noise is cancelled by design, please look that up as it goes too far to explain here. I think (my board is still unused) that an input RC filter is needed anyway when used unbalanced. This is standard practice with sensitive devices. The reason others use active preamps/buffers is the low input impedance of MA12070. That is then solved. The opamp stage also has very low output impedance preventing issues like pickup of signals. Your power on/off phenomenons should be solved by design with a muting relay shorting the outputs to GND at power on/off. For some reasons (cost probably) these are omitted nowadays but they bring great joy.
The question is what kind of noise and distortion occur unbalanced. Is it pickup of signals, is it 50 Hz from mains voltage ?
* The circuit of the MONO Infineon amplifier is helpful. Please look more careful. It converts SE to balanced input. Repeat that for the second channel (not connected in that schematic) and issues are gone.
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