PSU Upgrade Strategies for RasPi3 and Boss DAC --?

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I got my new iFi iPower yesterday. Tried it out for the first time last night.

There is an easily noticed, obvious improvement in the smoothness and 'listenability' of the playback with the iPower in place of the original Canakit PSU. Also, it should be noted that the iPower comes with a nice selection of adapters including the 5.5x2.1mm barrel to USB micro B necessary for the RPi.

Nice!
 
My initial thought would be to concentrate on getting some very good low ESR caps (OS-CON) onto the supply line, perhaps modding them onto the power input to the Boss DAC board.

I'd then look at an RF choke from the PSU to the caps. I don't think actual PSU is that important except that it should be quiet and of stable voltage, which I'd check with a decent (100MHz) scope. I've had PSUs who's burst RF noise appeared at the speaker terminals and it was basically impossible to get rid of, another, better switcher was fine.
 
Uh oh, trouble in iPower Paradise...

My initial thought would be to concentrate on getting some very good low ESR caps (OS-CON) onto the supply line, perhaps modding them onto the power input to the Boss DAC board.

I'd then look at an RF choke from the PSU to the caps. I don't think actual PSU is that important except that it should be quiet and of stable voltage, which I'd check with a decent (100MHz) scope. I've had PSUs who's burst RF noise appeared at the speaker terminals and it was basically impossible to get rid of, another, better switcher was fine.

Thanks for your reply, Globulator. Nothing ever goes easy for me. For some crazy reason, while powering the RPi3+BOSS DAC from the iFi iPower 5V really does sound very easy to listen to, I've become bothered by a buzzing noise coming from the left channel. I described it in this thread -- http://www.diyaudio.com/forums/pc-based/309101-allo-boss-dac-rpi3-ipower-buzz-hum-left-channel.html

In short, I get a ratty buzzing in the left channel audio only when using the iPower. If I switch the psu to the original Canakit 5V SMPS, no buzzing noise. Unless I hear of a miracle cure, this iPower is going back for a replacement or refund.

I'm beginning to think that I might get better results from an over-rated 5V SMPS (maybe a big Meanwell) and add additional capacitance and an RF choke for more smoothing.

On the other hand, there are a few people who think linear regulated 5V supplies work best with their RPi players. I have a few suitable power transformers, heatsinks and LM338 chips I could devote to this. I should get started on that.
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So here's my solution on vero board. The supply is based on 2 5V 2A Meanwell SMPS's each with a small filter on the output.

Using my dremel I removed all the unused traces on the mains side to minimise any arc over points or shorts.

I measured the PSU rails without load and then connected to the RPi3 & BossDAC. As you can see from the traces the BossDAC with all its own filtering is fairly clean. The RPi3 generates quite a selection of noise depending on what it is doing. Most noise is seen during boot but then settles down once all the services are loaded. Both traces were taken while playing a FLAC.

Hi garym,

Do you mind sharing values of you did filter after the meanwell?
Also what is the box at the input side of the smps.

I guess I will go with smp s for rpi. For the boss I will use linear.

Cheers,
Greg
 
Ok, I'll try to answer my own question.
For the output filter LC filter I would use 100-150uH (I can see 150 in the picture) and 220-330uF.
The other "thing" is probably a mains filter. I have seen a pc b mounted one.


Yep you've got it. The silver can is a mains filter not only is it cleaning up incomming noise it also helps to minimise what goes back up stream to the other mains kit nearby.
 
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