Different power supplies to the Raspberry Pi
Contents
We hook up different power supplies to the Pi. The Raspberry Pi runs on DietPi OS. We use the track ‘Labyrinth’ by Mammal Hands to hear the differences. Consecutively:
- The 5V power supply provided by Raspberry Pi itself
- The 5V power supply from DLink, which is supplied with the switch
- An iFi iPower2 in 5V
- An SBooster in 5-6V
- The Pura Dodo in 5V
Raspberry Pi power supply
Raspberry Pi’s own power supply doesn’t give great results. It all sounds a bit messy and dark due to a lot of pounding power in the bass. The highs seem to have a life of their own and the difference between bass clarinet and saxophone is barely audible.
Dlink power supply
The DLink power supply surprises positively. It all sounds a bit lighter and airier. The midrange is a bit dry and thin. Control over the bass notes is better than with the previous power supply. The piano still sounds a bit mechanical and the saxophone sounds squeezed.
iFi iPower2 power supply
An iFi iPower2 is a big step forward. The music takes on more timbre, more texture can be heard in the instruments and the musicians sound like a collective. In particular, it is suppleness in playback and reverberation that stand out compared to previous power supplies, making for a much more enjoyable listening.
SBooster power supply
Then the SBooster, which we put on 6 volts, for reasons explained later. This is a big step up from the iFi. The music becomes very rhythmic, there is a lot of texture in the cymbals. Especially the high frequencies are tamed down and gain depth in the sound. There is more layering in the stereo image, both in the placement in depth and in the sounds of the instruments. The dynamics in the piece are emphasised more, there is much more movement in the music and the contrasts become larger. It is mainly the transients that are much better than with the iFi. As we have noticed many times, the reproduction of transients is where the difference is made from a good reproduction to a lifelike one.
If we put the SBooster in 5 volts, it sounds like deflating a bicycle tyre compared to 6 volts. At 6 volts the energy and rhythm is palpable, at 5 volts it all sounds a bit muted. We spoke to SBooster in Munich about our findings with switches and they confirmed our findings. They gave us the tip to set the SBooster to 6 volts for our testing purposes. That has stuck, but it not a recommendation in any way.
Small note: at 6 volts, an SBooster delivers less current. If you want to connect a DAC via USB to the Raspberry Pi, an SBooster at 6 volts cannot provide enough current, it can only do so at 5 volts. If you are using Audirvana using UPnP or Chromecast, then the SBooster will provide enough current at 6 volts for a Raspberry Pi 4B.
Be warned: offering a different voltage than what is prescribed for a piece of equipment is always at your own risk
Pura Dodo power supply
We plug in the Pura Dodo and the sound changes considerably. It sounds very clean, for lack of a better description. There is a lot of control, quietness and detail in the reproduction. It gets close to the way the sound is reproduced with the Gigabyte computer, but does not reach the same level of authority, insight, detail and quality.
With the Dodo, you navigate more between the musicians, you are more in the soundstage, where with the SBooster you are looking on to a group playing together. Again, what you prefer more is a taste preference.
We just think that if this type of sound is preferred, buying a PC like the Gigabyte is the logical step. But the Dodo confirms that the quality of power supply is largely sound-determining when converting to RAW PCM. The extra horsepower of the Gigabyte computer’s CPU seems to add more depth to the sounds, it lifts the whole sound reproduction to a higher level compared to the Raspberry Pi with Dodo. But this could also be the power supply on the Gigabyte’s motherboard being more substantial for the more powerful CPU, not just the CPU itself. We don’t know what causes it, we can only note the outcome.
Hi,
When I started USB Async (UAC 1.1) back in 2003 I thought here it is digital freedom from jitter and other problems with SPDIF. Was I more wrong.
In 2010 I was at Rocky Mountain and a bunch of us were talking about why software sounds different. When I returned to the office that next week I cleared my schedule and put the following test setup:
MacBook Pro (with bootcamp Windows)USB Analyzer | both a Tektronix 4K series with USB and I2S plug ins and a Beagle Protocol Analyzer | Wavelength Wavestream module (basically a test set XMOS for companies using my USB to I2S software) with an I2S header.
Using flat WAV files (just made it easier to see samples) I ran that into the test set captured the USB and I2S and compared it to the original file. Actually told a few companies they were not bit true, but they had fixes really quick.
So after I had the new software and I determined everything was bit true I looked at Jitter. Ok well my Symetricon didn’t really show any difference in jitter on the I2S. I used my modified Stanford SR770 (good for noise testing down to 10nVrms at 1Hz) and saw a little difference in the noise on the power rails even though the unit was self powered. This was one of the reason’s at that point I started to think of isolation in my products.
I swapped out the Wavestream for several dacs I had on hand from my company and others I had done software with in the lab system and tried a bunch of different software. I then ask Atkinson and Charlie Hansen (RIP) from Ayre. Both of them said your nuts it could be anything.
I took the setup down and went on my way, not really happy with the outcome.
Years later I had this problem were my fan on my MacBook Pro was spinning like crazy. I asked my buddies at Apple and they suggested I load iStat Menus which keeps track of everything, super utility. Found a rogue device driver for my battery backup was taking up one of my CPU’s to 100% deleted it, reboot and everything was fine.
I was designing the AudioQuest Cobalt and I was listening to music on my AKG702 and was happy with what I heard but I went back through the software wheel and then it hit me!!! Products like Audirvana pre-load and decode the file into memory and then when interrupted by the system it just returns with a pointer to the next block of samples. Audirvana system usage 0.3%. I set the default sample rate for the file (88.2) and ran iTunes and it was 43% ok maybe we have something here.
I went through all the software and go some interesting numbers. Then I said ok, JTEST to the Prism dScope III with the Cobalt. Sure enough some differences. I have a break out USB board by Tektronix for testing USB and on that is VBUS and Ground so I hooked the Standford up and could see a difference in the power supply noise to the Cobalt.
Ok but why a difference when I use a self powered or even an isolated USB with reclocker? These computers have a boat load of clocks and switching supplies regardless of who makes them. I started measuring noise on the mains and sure enough the % of cpu usage and noise correlated. That noise goes back to the panel and into the system amps, preamps and so forth.
Yes isolation helps really well but there are other things I learned.
1) WIFI which we knows is really a bad network connection with audio in mind.
2) Your library interface should never be the same as your dac interface. Your basically doubling up on the transmission and reception and it’s all synchronous. Not good!
3) Memory the more you have the better off you are!
4) Laptops better sounding than desktops. FCC standards for laptops are far better than desktops and also the engineering going into laptops over desktops is almost 10:1. Mainly for energy usage which from above can be a real difference.
5) The OS makes a difference but the application makes more.
6) Sample rate… funny but upsampling to really high rates is not a good idea. The dac chips really don’t sound better at 768 compared to 88.2 or 96. I think that is heat related plus how much work the CPU (yes they are processors now) can do between samples!
The big thing is…. computer audio is not a slam dunk. Trial and error can really make a big difference in the sound.
Have fun, and thanks great topic!
Gordon
Wavelength Audio, ltd.
Hi Gordon,
Thank you for that long comment, much appreciated. I edited it slightly for better readability by adding some white lines in between. I think that will help more readers to actually read what you wrote 🙂
There’s one thing you say that caught my eye:
“Your library interface should never be the same as your dac interface.”
How should I interpret that, if you have a computer networked through ethernet where Audirvana is running and a streamer/DAC that is connected on the network as well, and you use UPnP to stream from Audirvana to the streamer/DAC?
Correct, in that case you have 2 synchronous streams running against each other. This would not be an optimal setup. A better one would be local storage and then stream via Ethernet. Or USB DAC and pull from files or server over Ethernet. WIFI of course has 4x the traffic so I don’t suggest that to users.
Thanks,
Gordon
I´m getting the feeling that you are concluding, or working from the hypothesis, that noise in the digital domain is mainly the problem when it comes to the variation in sound quality in the digital domain. The source of this noise could come from many different places, even software generated CPU noise, right?
What i find interesting is then the talk about taste, in this matter. Taste is of course taste… and we can´t change what people like and perceive. But at the same time, the best sound should be created if we have NO noise getting into to the DAC/Clock, from what i understand. (even if there always will be some level of noise) Then the DAC conversion has the best possibility to recreate that digital feed exactly correct as it was captured in the ADC process.
My thought is that we should at all cost (if we want or care) remove the noise in the digital domain and this should ideally never be driven from matter of taste. Otherwise it feels a bit like saying that i prefer that my vinyl records and stylist is dirty and therefore i keep them dirty, which is of course ok, but not something we want to suggest doing because you like it.
If we want to match the sound with our taste, that should ideally be done somewhere on the analogue side, at least not before the DAC, in my mind.
Just some philosophical thoughts 😀
You can also “split the processing” among the cpu cores of a single computer, which is what I’ve been doing with a 8Gb RPi4 running Audiolinux as a Roon endpoint. Starting with Allo’s SBC-based DigiOne and USBridge transports six years ago, I’ve played with several stripped-down OSs (DietPi, Volumio, PiCore Player, VitOS and, now, Audiolinux) and different players (Roon, AV, Squeezelite) to find what sounds best to me through my Meridian active speakers.
Isolated cores can make a difference.
Thank you for that addition.
Amazing work Martijn and very interesting observations! As you have alluded to earlier I really like that you take the approach of “not knowing anything” when going into your tests and don´t assume anything. I make some assumptions my-self but its good that you don´t!
Maybe this question is out of topic, but i can´t get away from wondering what the plug´n-play streamer sounds like in comparison with fiddling around with these software´s yourself. I get that the Raspberry Pi is much cheaper, which is an interesting prospect if it sounds similar, or better, than the Motivo on its own, but does it?
Is it worth going down the software rabbit whole, from a sound quality perspective, if you already own a streamer, similar to the Motivo, with good power supply for example?
To make my self more clear. Let´s say i use the Tidal App in Motivo which is not connected to any other computing device in the signal chain. Is it then worth exploring other software alternatives using a Raspberry Pi instead, if all the connected hardware in the signal chain is the same? (again, from a pure sound quality perspective)
Hi Tobias. Good questions.
First of all, we don’t create our own streamer in this test. We add a music server to the chain, and still use a streamer. We don’t use much of the Volumio software in this case, but we still do and utilise all the work Volumio has put into designing the signal chain within the Motivo.
We could have used the Primare NP5 Mk2 instead of the Motivo, or the Volumio Rivo, but those streaming bridges would need a very good power supply, the Dodo in our case, to prevent them from becoming the weakest link in the chain of this test and thus influence the outcome.
We needed the Dodo power supply for the test setup. That’s why we chose the Motivo: we know it is optimal with its own power supply and it is a very high quality streamer. I think a lot of people underestimate how good it is.
To return to the question: comparing the Motivo on one hand and a Raspberry Pi running Audirvana Core Player with the Motivo on the other hand, will result in a different sound signature, because of Audirvana software. If you compare like this, it will be hard to tell what attributes to the sound and draw any conclusion.
But what would happen if we add a Raspberry Pi running Volumio software next to the Motivo and compare to using the Motivo stand-alone? Because that would be the right test to see what the effect of adding hardware and splitting tasks across computers will add. I don’t know the answer.
I will try to see if I can use the Volumio software on a Pi to stream to a Volumio device, just like Audirvana can. I’m not sure if the Volumio software will be able to work this way, but there’s only one way to find out! If we compare like this, we would be able to conclude something. That will be a fun test, thank you for bringing up the suggestion.
If you look at the high end market, to for example Antipodes music servers: they use different computers for different functions: storing music files, running the music library software and processing the sound.
Also Grimm uses two computers in their players: one running Roon and one for the processing of sound. Of course, these expensive machines have a lot of custom hardware, it is not just tying together a few computers and a streaming board. From visiting Grimm (to be found in the archives of this website) we know they research and engineer a lot when creating their players. But, given that manufacturers like these split the music processing across different computers, each dedicated to specific tasks, you can deduct that doing this yourself has added benefits. But you also introduce new sources of noise as well, so it is not that easy to do it right.
Thanks for the detailed answer. I really had concentrate and read several times what you where saying since the complication of the noise problem is really intricate and all the variables involved makes it hard to compare apples with apples, i see that now. Thanks again for your work for the audio community!
I’ve tried to see if I can stream from a Pi running the Volumio OS to a Volumio Motivo. The answer is ‘no, you cannot’. Volumio OS cannot send a signal to another device using UPnP (like Audirvana or any other music player communicating over UPnP, being the UPnP server), it can only work as a UPnP renderer (meaning being the receiver of music streamed through UPnP).
When connecting on USB, the Motivo isn’t seen as a USB DAC by the Volumio OS running on the Pi.
So, unfortunately, I cannot test this scenario.