I recently got a raspberry Pi to be used only as a Flac player combined with volumio. I am planning to use it with an Indeed TA2021S + HifimeDIY Usb sabre 2+ HifimeDIY external power supply PSM3+ (i hope they arrive on the next days).
I am doing a research for a value for money (max 30 euro) power supply 5V 2A for the rpi. I have read the article on raspyfi blog but at the moment i haven’t found any solution with regards to the price range i mentioned. The only power supply i have in my hands is a Nexus 7 charger.
Any suggestions regarding the above are highly appreciated!
I bought the standard R-Pi power supply (1.2A, 5V, looks like one for cell phone chargers) and then I measured its output with an oscilloscope before R-Pi, after voltage regulation inside the R-Pi board, and also in the USB 5V line.
The variations were extremely small in the R-Pi board after regulation and definitely not worth buying or spending time on anything else (or: feel free to do it, but you get nothing from it).
On the other hand, the USB power line was oscillating, because the same one is used to power the LAN and other LEDs, that affect the voltage on the USB line. The oscillation however had the same frequency of on/off of the LEDs, that means no more than 10 per second, therefore, realistically, only those frequencies MAY be affected.
If you are worried about power supply (and you shouldn’t, it’s just audiophile paranoia), you should look into an USB audio device that has a good power supply, external.
The R-Pi supply doesn’t matter much and it’s as good as needed for audio purposes.
and who cares? USB devices are designed to work with 4.75V input… and the R-Pi itself lowers the voltage internally to 3.3V, therefore it has also no problems with a normal supply giving out 4.75V.
BTW: the standard R-Pi supply I bought never went that low, they are exaggerating to sell more.
in my first days I used a 1.2A 5v switching PSU (from old iPhone) and experienced some random crashes when the wlan was very busy. now I’m using a 2.4A PSU (a spare iPad one) and no more crashes.
If the RPi PSU is giving the right juice amount, there’s nothing about “audiophilia” you ask to it, while amp state PSUs are very important to the final sound quality (pre amp and amps).
if your DAC preamp is USB powered you have to worry about it but my advice is to buy a better dac other than a better PSU (or to mod your preamp to make it externally powered by a nice toroidal transformer as I’ve done)
Yesterday I had a very bad experience with the psu of the above post.
I received my tripath amp and I was able for the first time to test my new toys:
I was very disappointed from how it sounded and I started changing the volumio sound settings to get a better result. The sound was worse than my standard pc sound with my pc speakers and when I tried to raise the volume it began to heavily distort.
Suddenly the raspberry stopped working and I realised that the psu was dead. I took a tablet charger and put it immediately and everything started working as it should.
As it seems I have to be more careful with the choice of the psu I will buy in the next days.
You realize that those measurements are useless right?
The only measurement someone should make is to play a standard 1 kHz tone and check the analog audio coming out, to see if different power supplies are ACTUALLY affecting the final sound.
No one does it.
Because audio amps and DACs are quite insensitive to input noise and even the cheapest power supply would not impact it enough to change the sound you hear.
I’ve used old PC PSU’s pretty much since I got a Pi and Arduino and never had any issues of any kind. Cheap, Clean power. separate 12V supplies for amp inputs and a fan that comes on when you need cooling - which might tell you something else is up that you want to look into.
Maybe its just because I have 4 power supplies sitting around from old PC’s going back several years, but I just dont see the problem with needing a 5V or 12V supply in this day and age.
my 2 cents.
But that’s offtopic. I’ve just finished my double 5V PSU- prototype.
It has been tested with hifiberry dac and digi and- to me- it’s a step forward in sound performance.
Have a look:
PS: Lag-na- please don’t klick it if you aren’t in a very relaxed mood There are things to see that you would call sheer madness :mrgreen: flickr.com/photos/125186975@N06/
For everyone who is interested in such a modification:
DIGI or DAC are extra powered
Therefore the 5V pin on the P5 header of the pi should be cut off or removed
Afterwards you are able to power the little boards via their own 5V inputs
BUT! You will loose onboard fusing with this method!
I didn’t care
Take 2 good PSU’s or build up one on your own with two completely separated 5V rails.
Power the pi through the micro USB port with one rail- the other rail is for the dac or digi only- you can solder mini- board- connectors
to the dac’s or digi’s 5V input (as shown on one of the fotos) so you are able to easily connect and disconnect if necessary.
Please note: !Keep in mind that dealing with mains voltage may endanger your life!
Moreover it might happen, that you brake your devices if something’s going wrong!
And- of course there are no guarantees for this information.
There’s a shot of noise performance of the advanced PSU I got from my 35 year old Hameg 312 (Separated 5V Rail to Digi)
Unfortunately the camera thickens up the line a little bit- reality shows a significantly sharper line : flickr.com/photos/125186975 … 340180445/
Noise seems to be very low- the device is adjusted at 5mV per section. But I’m not sure if I can trust the result.
Maybe I’ll get the chance to take measurements with an up to date device soon.
What I’m worrying about is that noise increases when playing web radio via wlan dongle. Noise increases up to near 1 mV in this case.
Playback via hdd delivers noise far beyond that mark. Might be better with ethernet connection and cut ground shield.
A problem I’m suspecting generally is the still active ground connection between raspberry pi and the dac or digi. I have to take on further more research if there are other possibilities. But- sound is great anyway! To me- it makes much sense to put some effort in optimizing power supply.
I’ve been looking for a cheap, clean source of 5V power to test my Cubox-I with a DragonFly DAC, and this us just the ticket. Had plenty laying around, and did not even think about it until I saw this post.