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MA12070 / MA12070P Amplifier Boards


Nixem
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Hi all, just wanted to make this thread for the Infineon MA12070 and MA12070P amplifier boards. If anyone has any experience feel free to share!

I am interested in the P version, running direct i2s from an adau board. 

At the moment, I am not sure about running multiple PBTL mode boards (3-4) on a single smps power supply, and if any special considerations need to be made, like multiple i2s amp boards on 1 PSU would need decoupling capacitors. Any ideas appreciated, I do not have much experience in this area.

 


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123Toid
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@nixem @ajc9988 and @elliottdesigns do you guys have any input here?

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ajc9988
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Posted by: @nixem

Hi all, just wanted to make this thread for the Infineon MA12070 and MA12070P amplifier boards. If anyone has any experience feel free to share!

I am interested in the P version, running direct i2s from an adau board. 

At the moment, I am not sure about running multiple PBTL mode boards (3-4) on a single smps power supply, and if any special considerations need to be made, like multiple i2s amp boards on 1 PSU would need decoupling capacitors. Any ideas appreciated, I do not have much experience in this area.

 

So, many smps power supplies are single rail. Some considerations to have is peak transient amperage that may be called on the power supply with so many boards. For a linear transformer, you can just put a slow start to help suppress the instant call for power so it doesn't slam down stream when you turn on the power supply. With an SMPS, it depends on nuances related to the design on if it has something to help arrest the transient hit of power for peaks or even turning on the setup.

And with bridging, it may request up to 640W instant upon being turned on. Then, you have to remember the SMPS is not fully efficient, so if you spec'ed the power supply too close to the draw on the 4 boards, pop goes the power supply. I would recommend between 20-50% more than the amount you plan on drawing regularly from all of the amplifiers, which 20% should somewhat keep the PSU safe, but then you need to also figure out the possible transient peak pulls of the amplifiers under load. Those peak transients, if they last over a certain amount of time or pull too many amps, you could pop the power supply with the surge. Think of power like water, if you have too much power go down a tube just to hit a wall, that wall has to absorb A LOT of momentum. In the same way, if the transient amps pulled exceed anywhere in the chain, you can pop something.

So, try to figure out the transient power pulled and the terms for when over current protection kicks in, so that if it does have enough capacity to handle that many amps, that it won't kick the OC protection every time you turn it on or when you crank up the volume.

That means if you got a 1000W power supply (56% over the potential 160W per board bridged), you will leave headroom for the power supply of 20%, then you will leave room for inefficiencies of the amps (which could be an additional 6-40%, I do not know your amplifier boards and haven't seen if the board has been benchmarked for efficiency, which means you may pull even more than the output levels, depending).

Decoupling capacitors or input buffer boards can sometimes help alleviate what I discussed for the initial power slammed into the device (they use input capacitor filters for CPUs on motherboards to help combat the transient effects, so this should help with that concern to a degree as well).

Now, decoupling capacitors or input buffer boards/power filter boards (do not confuse the latter with rectifier boards which also contain a large number of filter capacitors as a rectifier shouldn't be needed in this situation but is required after the toroidal transformer) can have additional benefits of further smoothing PSU ripple, which you may have if you do not use an SMPS where they test for ripple which can effect audio components (all should test for ripple, but there are different acceptable amounts of ripple depending on the use case). So I will not discourage that practice of putting in a filter bank before providing the power to the amplifier board, just on certain considerations other than your question. 

But the main thing is making sure the power supply is suitably rated for enough power that it can handle that much load onto the supply, that the ratings for over current protection are enough that it can handle the transient loads demanded of the power supply, etc.

There is also the question of the power from your mains having dips in voltage that can disrupt things, but that is less likely to cause the catastrophic destruction found in over current. Look for a power supply that can has under voltage protection and know that filter banks that are large enough can help with this to a degree. 

Direct i2s is pretty cool. I would need to research more the chip's handling of the signal. ( https://www.infineon.com/cms/en/product/power/class-d-audio-amplifier-ic/integrated-class-d-audio-amplifier-ics/ma12070p/ ). That said 93% efficiency on the chip at full rated load @8 Ohm, but that doesn't mean there is not other inefficiencies of the board on which it is deployed. Just to give another data point.

I hope some of this made sense and if I misstated anything, anyone else can feel free to correct me. This is my current understanding, but that does not mean I cannot be wrong on certain points.


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ElliottDesigns
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@ajc9988 Couldn't have said it better myself.

 

The reference boards look of high quality and the fact that they are filterless is definitely a plus. I'd say it might be a lot easier (and possibly even cheaper too) to have separate power supplies. As for supporting peak current draw (mostly needed in the bass region since a lot more energy is needed to move the cone), for this I would recommend replacing the onboard capacitors, but that can be difficult since they are of a surface mounted type, so it's difficult not to ruin the traces or pads on removal without a hot plate.

Elliott Dyson - Mechanical Engineering Student and 3D printing & Design Freelancer


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Nixem
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@ajc9988 thanks so much!

Edit: not sure if the below would work because of the minimum voltage may be 28 for that PSU. One of the reasons I am trying to do one PSU is physical space limitations.

I have been eyeing the Connex SMPS800RS ( https://connexelectronic.com/product/smps800rs/) which says has 1000w peak.

I was hoping that would be sufficient for 4 PBTL. I think Sabaj is using a 350w for two PBTL chips on their a20a, which I think may be larger than similar SMSL implementations. 

 

Do you think I would be ok to simply wire 4 boards up in parallel to the SMPS800RS supply?

These are the test boards I'm looking at atm: (v1.4 "P" version): https://www.aliexpress.com/item/1005001810845146.html

 

Thanks!

 


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Nixem
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@elliottdesigns 

Do you have any thoughts on the reference board vs the Shenzhen boards?

 

Reference: https://www.infineon.com/cms/en/product/evaluation-boards/ref_audio_d_ma12070p/

Shenzhen: https://www.aliexpress.com/item/1005001810845146.html

 


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ElliottDesigns
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@nixem 

It's difficult to see exactly since the reference board image is quite blurry, but they seem to have the same components. Apart from the fact that the Shenzhen one has what appear to be gain switches which is useful if you don't have an Arduino and it also has a heatsink which may or may not be helpful since it's designed to be run without one.

So I'd say, whichever is cheapest depending on your region. One thing for sure though, the reference board is designed by the chipmakers so they should know what they are doing with the layout more so than Shenzhen, but that I do not know for sure. Maybe the layout differences only affect the size, but there is a possibility of slight detriment to audio quality, but I doubt it would make any noticeable difference either way.

Elliott Dyson - Mechanical Engineering Student and 3D printing & Design Freelancer


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ajc9988
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@nixem - for more on the reference vs the shenzhen, I would probably go with whichever is cheaper. I noticed the shenzhen has gone with smaller surface mount capacitors around the chip. This can help with quick transients. For a discussion of surface mount caps, I recommend you look at the recent discussion of the Nvidia 3000 series graphics cards and the cap selection on the backside of the PCB underneath the GPU die.

https://www.techspot.com/news/86900-capacitor-issues-causing-rtx-30803090-crashes.html

https://www.techspot.com/news/86916-card-makers-respond-rtx-30-series-capacitor-controversy.html

The issue was basically resolved with a driver update which lowered the speed of the cards almost imperceptibly. But, the discussion of the capacitor choice is interesting nonetheless.

With those two designs, without more information on the surface mount components, I cannot say much other than they are likely functionally equivalent. Multi-level ceramics can have better transients. But I need more on what was used to truly understand what is going on.

As for the PSU, if unsure, have you considered contacting the manufacturer to ask if they think the PSU (Power Supply Unit) can support it.

I was busy yesterday and am just drinking my morning coffee, so I will try to give a better answer on the power supply later today (sorry for the delay). But I did want to mention most companies, if you have a highly technical question, are happy to kick you over to talk to someone that can answer that question (mainly because a good answer can lead you to a sale). So you might shoot them a question like that and they may recommend the single power supply or instead to get multiple less powerful ones. Like the cost of their 250W supplies, if buying 4 of them, comes out to double the price of the single larger power supply. But there is no question it could do the job asked of them at that point. But I would say ask the company.

I'll try to give a better answer later.

Edit:

Noise information on the boards:
Shenzhen:

6. Audio performance (PMP2) : >110dB SNR (a-w, relative to 1% THD+N power level), no complex dynamic following power supply design (with conventional sound power supply design scheme to improve energy efficiency).

7. 45 V output integrated noise (A-W), which does not require A low pass filter (LPF) in most applications.

8. THD+N is 0.004% for high output electricity.

 

Reference:
Audio Performance (PMP2)
>101dB DNR (A-w, rel. to 1% THD+N power
level)
140μV output integrated noise (A-w)
0.007% THD+N at high output levels

 

So, in theory, even though functionally equivalent, if they tested the THD+N the same way and properly, the Shenzhen has an edge. There is also a question of accuracy of the test equipment used. But, just wanted to give hard information from their claims on which one could make a decision.


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Nixem
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@ajc9988 off the top of my head, the Shenzhen and reference difference may be the 12070 non P vs P version. The P version has worse dynamic range and thd+n if I recall. One of the tradeoffs with not needing to use a DAC.


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ajc9988
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@nixem - On the power supply question, I saw an interesting video with Laurie Fincham just now (

In it, when they discussed the 120dB speaker that they built, it said in the article they used 3 power supplies to power 8 amplifiers for a 1600W speaker. If you look at your question, I would, on this basis, look into using 2 power supplies for the 4 boards. This would ensure proper loading without having as much to worry about. Just wanted to throw that bone I found to you.


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TVOR-Ceasar
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@ajc9988 is that video from Erin's Audio Corner? Just asking because it gives a playback error.

I had a good post all written out yesterday, but got logged out between posts, so I lost it.

Power, when it comes to figuring out how much you'll need, it goes way deeper than just how much for the output. You'll need to get the max draw for the whole circuit just to get a baseline. So, you'll need to know what the boards will take in standby as well as when under full load ( max draw MAY be somewhere around 70-85% of full power with some devices). For example, you'd need whatever the Bluetooth or WiFi would draw, plus the ADC/DAC and processor plus whatever preamp may be included, along with the power amp output at it's least efficient. You'll find the power needed adds up to a decent but more than just amplifier output. For instance, an old analog receiver I had years ago was maybe 5 watts output, but with all the other circuitry in use, the power consumption was listed at 45 watts. Big difference from the supposed 10 watts it might deliver.

So, once you get your baseline, you have to know that that is the thinnest line you could hold and get acceptable performance without killing the power supply. At this point, you'd need a buffer, say 30 to 50% higher, and depending on how hard you want to use it, up to or even exceeding 100% higher capacity, just to make sure you don't severely stress the components in the power supply. The more you stress them, the weaker they get, if the stress is too high for too long.

If you are wondering why such a buffer, think about the way many things are built these days, with ever shrinking components. It's not that the components can't handle the current, it's that they have less surface area to dissipate the heat caused by the high currents they have to handle. Not only does the heat harm the components, it cycles the solder, possibly allowing things to shift and come undone or cause arcing if one side comes loose. 

So when looking at supplies, also look at how they cool themselves and how they are constructed, and take that into consideration as well as just total output. 

Good luck on your search.

-Charlie
https://www.youtube.com/user/TheTrueVoiceOfReason


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ajc9988
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@tvor-ceasar - That is Erin's Audio Corner. So if you go to youtube, you can find it. This talk is about cabinet resonances and how to make a cabinet from a manufacturer's perspective. It was a good talk, but I came in late, so I have to go back and rewatch it.

Erin has had some good interviews on his channel.

Edit:

image

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ajc9988
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@Nixem - I'm including this video on power supplies for computers. Although it isn't precisely dealing with power supplies for audio, the testing and the elements discussed in the video other than the rating for efficiency really touches on many things I mentioned above and can serve as a resource. So I'm adding this video here. Gamers Nexus, "The 80 Plus Problem: Rigging results, misunderstood ratings, & limitations"


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