Blog Forums DIY Amplifiers and Electronics MA12070 / MA12070P Amplifier Boards Reply To: RE: MA12070 / MA12070P Amplifier Boards


@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.

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.


Noise information on the boards:

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.


Audio Performance (PMP2)
>101dB DNR (Aw, rel. to 1% THD+N power
140μV output integrated noise (Aw)
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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