Simple power supply tweak using HDMI - amazing improvement!

[jesper]

I have had an interest in improving my existing audio equipment and recently discovered RPi and RuneAudio. I saw its use as a music server, adding a DAC to deliver some good sound streaming my music in my network. Well, I didn´t have any DAC for the RPi (version 3B) yet, still having sound going out via HDMI.

I started out setting it up just using my iPad charger as power supply. I´m using the HDMI out signal from RuneAudio to send the sound digitally via a Supra HDMI cable to my preamp Emotiva UMC-200 and then via twisted pair single core RCA cables to my active speakers Emotiva Stealth 6.

The sound I got was, let´s say questionable. Streaming it to my AppleTV 3 gave better sound, but that involved having iTunes running on a computer which meant connecting my HDD to my laptop, starting it up and then start iTunes + turn on my preamp. This was too complicated, so here is where the RPi got interesting to me using it as a music server.

Now, I understood I needed a proper power supply and I finally decided to get the iFi iPower 5V. The very nice linear power supplies were just too expensive for me. Well, I just plugged in the iFi IPower and that made a substantial improvement in the sound. It now sounded a bit better than via my AppleTV 3. Nice!

Now I was on the plus side, but not satisfied with the quality. It must be able to tweak this RPi, I thought. I read the RPi´s clock caused jitter problems that could be solved by a master DAC rechecking the RPi and DAC, but I yet don´t have any DAC to do that. Looking at the RPi´s board I didn't really see any capacitors that potentially could stabilise the power on the RPi. So, I got the idea to add some capacitors. I decided to just try out some capacitors I had at home. The choice fell on two high quality capacitors:

1. ELNA LongLife RSH(M) 25v 2200uF
2. RIFA PME271M 40/100/56/B 250VAC 220nF X2

The ELNA capacitor should be able to have a big reservoar of easily accessible electrons for the RPi´s power consumption, and
the RIFA capacitor for stablising any small spikes due to varying power consumption operating far up into the megahertz band. Well, that was the idea. I wanted to add the capacitors between the iFi iPower and the RPi as close to the RPi as possible.

I soldered a cable having two wires (fitted with a female power plug for my iFi iPower) onto the RPi´s print (GND and +5v) under the mini USB power connection. Then I took off 5 mm of the 2 wire´s isolation close to the RPi´s print and soldered the 2 capacitors in parallell onto that cable. Done.

I installed the RPi again, plugged in the HDMI, network cable and the iFi iPower onto the new connector with the 2 capacitors on and started up the system. What happened to the sound? It was just breathtaking - no short of amazing! The sound stage opened up in both depth and width really much and now I don´t hear the individual speakers any more and I´m presented with a huge sound stage! Wow! Both instruments and voices are presented close to having them in the room playing live. The bass goes much deeper and there are no harshness in the high tones at all playing AAC Lossless 44.1 kHz stored on a network HDD.

I have never heard anything as good sounding as this before. Wow, wow, wow!
Using the CD quality format (44.1 kHz lossless) I wonder how much more room for improvement there can be using a good master DAC that will recheck the RPi. I have ordered the Allo Boss DAC and look forward to testing that, but for now I´m just amazed!

Kind regards,
Jesper

[jesper]

Ops, "rechecked"... Should of course say "reclocked". Auto correction error...

[jesper]

So, I got the Allo Boss DAC today and installed it using RuneOS ver 0.4b, which have pre-configuration in the graphic user interphase (GUI). That´s the same used when doing the above tests.

First I listened to the sound with my setup of sound via HDMI to the Emotiva preamp as mentioned above, but now adding the Boss DAC - just plugging it in on top of the RPi and turning on I2S. The result, I was curious to what this very precise clock could do a clock which reclocks the RPi when I2S is turned on having less jitter than 0.63 nano seconds - well below the hearing level of variation in jitter.

First impressions with HDMI setup
It was better, but only slightly better than with above setup. This means that the capacitors above did the trick of very much reduce jitter of the RPi. That´s kind of an amazing simple trick (in combination with iFi iPower) to reduce the infamous RPi´s jitter problem. And note I´m playing 44.1 kHz, which have been reported give most problems. That is a highly recommended upgrade to most users of the RPi, but don´t use some shitty capacitors and expect good results - use only really good ones with low inner resistance.

Next setup was using the RCA out (analog) from the Boss DAC
This sounded somewhat different, big and wide picture, good, but less natural sound and a bit thinner. Ok, now I have to say that the Boss DAC is new and didn´t get run any hours to "break in" circuits, it´s just out of the box sound. And my preamp didn't´t sound so well either when out of the box as it does now. What I can say now is that my Emotiva UMC-200 beat the shit out of Allo Boss DAC so far. This is not to say that the Boss DAC is bad - it´s not - it´s quite nice! But what it means is the Emotiva UMC-200 is great stuff! Just so you know, the Emotiva preamp has a Room EQ, but this was turned off wile comparing.

In my setup, the Allo Boss DAC so far have not been worth the about 85 € of total for getting the Boss DAC - the most expensive single component used yet and the one producing the least added benefit in my setup, at least for now. But I look forward to see how it will play after having been "broken in". The Allo Boss DAC should not be rulled out in my setup, and fine Emotiva is High End gear, maybe not a fair comparison. It can be said though that the Emotiva benefitted immensely from reduced jitter!

Well, I´ll be back giving a report on how the "broken in" Allo Boss DAC sounds.

[jesper]

Ok, an update on the Allo Boss DAC:

I kept playing it now for a while, but still up in about 20-25 hours, so it´s not yet run enough time for final decision. I can say it´s improving, but the mid range and voices I'm not satisfied with.

I decided to look into the Boss DAC's analog power and found that the DAC uses 3.3V, not 5V. this means there needs to be some proper capacitor to stabilise the 3.3V as well. Out with the DAC and solder another capacitor onto the board

I took a polypropylene capacitor of 1.5uF (ICEL MPL 160V K5 1.5uF 1%) and soldered it to the Boss DAC board at the big capacitor located between the PCM5122 and the left (white) RCA. It looks blue and yellow on allo.com's pic of the Boss DAC.

Now, the troubles in the mid range and voice are gone and the sound opened up - just an amazing improvement!
Now the sound is already fantastic! Wow!

So, the power supply of 3.3V MUST have a bigger, better capacitor to get the ALLO BOSS DAC to perform better in the mid range.

Now get out your soldering iron and a few capacitors and rock the place! I´d like to hear from someone who dared to try this tweak too. You won´t regret it (unless you don´t know how to solder)!

[hondagx35]

Hi jesper,

thank you for sharing this.

Frank

[Stephane]

This means that the capacitors above did the trick of very much reduce jitter of the RPi.

Hello,
Do you have a screen-copy of the oscilloscope showing the improvement?
Thank you.

[DJ le Roi]

Ok, an update on the Allo Boss DAC:

I kept playing it now for a while, but still up in about 20-25 hours, so it´s not yet run enough time for final decision. I can say it´s improving, but the mid range and voices I'm not satisfied with.

I decided to look into the Boss DAC's analog power and found that the DAC uses 3.3V, not 5V. this means there needs to be some proper capacitor to stabilise the 3.3V as well. Out with the DAC and solder another capacitor onto the board

I took a polypropylene capacitor of 1.5uF (ICEL MPL 160V K5 1.5uF 1%) and soldered it to the Boss DAC board at the big capacitor located between the PCM5122 and the left (white) RCA. It looks blue and yellow on allo.com's pic of the Boss DAC.

Now, the troubles in the mid range and voice are gone and the sound opened up - just an amazing improvement!
Now the sound is already fantastic! Wow!

So, the power supply of 3.3V MUST have a bigger, better capacitor to get the ALLO BOSS DAC to perform better in the mid range.

Now get out your soldering iron and a few capacitors and rock the place! I´d like to hear from someone who dared to try this tweak too. You won´t regret it (unless you don´t know how to solder)!

This sounds very interesting! Is it possible you show me a photo of the modification?

[jesper]

Hi Stephane,
No oscilloscope pic as I don´t have one, but I can assure you that the sound improvement is very obvious, at least in my setup. I trust my ears better than a test pic, but of course that would be interesting to see. If someone that has an oscilloscope and could do this simple tweak I would also like to see the pics. I guess someone having moderately good speakers might not get the same results, but I´m quite sure it will be obvious to the listener. The speakers I have are high end - very good indeed - which, after this tweak they really prove to be. I actually disconnected my subwoofer for music listening as it goes so deep and I even have to cut off 2 to 4 dB on the sub channels (active speakers), and these are 6,5" only!

The tweak is so cheap (10-20€) that I honestly think it´s worth trying. If you have some good capacitors laying around, like I had, the tweak is more or less for free. It´s for sure THE BEST improvement for the least money in my setup.
Kind regards,
Jesper

[jesper]

Dear DJ le Roi,
Pics, of course. As you see it´s in the tweak stage - no box, etc. but that will come later.

Here is the 1,5uF polypropylene capacitor soldered to the Boss DAC:

Allo Boss DAC capacitor

IMG_5920-1.JPG (37.03 KiB) Viewed 7233 times

Here is the tweak with two capacitors, mentioned above, soldered to the 5V power input of the RPi fed with 5V from iFi iPower:

RPi capacitors

IMG_5922-1.JPG (42.45 KiB) Viewed 7233 times

Here is one of my speakers. Note the stones under and on top. These really improve the overall sound and especially the bass becomes very deep having these, as it will not move - about 9 kg/stone! Also note the power cable to the speakers (red, black, yellow) and the thin blue ones. They are twisted, which improved the overall transient response.

Emotiva Stealth 6 active speaker

IMG_5924-1.JPG (32.02 KiB) Viewed 7233 times

Kind regards,
Jesper

[jesper]

Ops, speaker pic rotated to the side. Lean your head to the left...