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

#14288
tvor-ceasar
Moderator

@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.


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