Raspberry Pi2 and Hifiberry Digi+: A cheap transport that made me happier

Scott is that a kit and where did you get it? Looks like a great DIY project.

 

http://www.diyinhk.com/shop/audio-k...e-dac-power-supply-regulator-3357v-15ax2.html

 

@Vastx: I didn't see on the diyinhk page... what voltage input does that regulator accept?

 

On the pcb it says 6-8V (ac).
Diynk told me 9vac to get the 5vdc and 7 vac to get the 3,3dc.
Imo it is conservative. I'll try first a 7Vac.

The regulator itself can obviously take more but you are limited in this kit made to provide 3,3\5\(7) Vdc.

Note the warning on center tapped transformer.

 

It looks like a well thought out kit, components are very nice. Wima capacitors etc. No instructions needed, the silkscreen has everything on it. Looks like a lego kit

Once one is together I'll measure the 5V,3.3V output using the 7VAC input, check for heat... run a pi for awhile etc.

 

I love it: "Caution : For Audiophile DIY use only"

I really enjoy reading this stuff. Keep up the good work...

 

FYI, we've talked to Daniel (HifiBerry) about the possibility of a Digi+ PRO

https://support.hifiberry.com/hc/en-us/community/posts/201496372-Digi-Pro- and a little here: https://support.hifiberry.com/hc/en-us/community/posts/201496272-Removed-Toslink-added-BNC

His stance is the PLL in the WM8804 is very good, and to get the best performance, you should probably not be using SPDIF anyway... should be using i2s out of their Dac+ Pro.

He's probably right about SPDIF, but some of us don't want to give up our DAC's without i2s in just yet

 

< Noob Alert >
I stumbled across this thread, and am wondering how isolating the playback from a PC affects/improves sound quality. Can I expect to hear differences with just a Raspberry Pi outputting USB to my DAC vs. PC > DAC? And then more improvements going to S/PDIF > DAC? What are the reasons for these improvements? Has anyone tried measuring the differences? Is using the Raspberry Pi as a transport equivalent to a really good USB decrapifier? Nobody seems to be talking much about using TOSLINK. Is this because it's not a good output to use, or just that your DACs don't have optical inputs?

Thanks for your patience in answering my questions!

 

Well, didn't blow it up yet. Measuring good 5V or 3.3V (depending on what you set it to) using the 7VAC in. Runs cool.

The Digi+ there now is using the LT3042 LPS, underneath the piZERO, has pins 1,17 removed (the 3.3V).

Using my other LPS supplies (LT1085 based) to power the pi separately, and wifi separately. (This keeps the pi at a very stable 100mA) with wifi direct, or ethernet dongle, big 100mA-220mA swings continuously -- not sure this help yet, but it's an interesting theory.

BTW, that Digi+ board, only draws 13mA, when playing 24/192!

--gonna do a video, these images are clips

--also in my AudioSystem link, there's another link full of my notes configuring piCorePlayer, and some Hardware stuff, I change it here and there as we go.

If anything we have a nice base here... to compare to how it should *really* be done, the D1 & D2 !

Sounds so so pure


Is this TMI? I can tone it down...

 

Nope it is GREAT! REally nice to have some sort of guide as a reference. How does this compare to a normal good qaulity SMPS in listening tests?

 

@Scott Kramer
Thanks for the update. Is the lt3042 stable under load ordoes it drop? How would you rate the sound quality of the psu compared to something like the lt1085 you have around?

 

Thanks for your reply. I also done some reading/lurking and still don't really have a real grasp of the subject (USB async, jitter, clocks, etc.). I don't think the differences are due to getting all the bits through, because if they didn't you'd be hearing glitches rather than just unimpressive sound. It must have something to do with the accuracy of the timing resulting in more accurate D-to-A conversion further down the path. Perhaps noise can throw the occasional bit one way or the other, also affecting the integrity of the digital signal.

Hopefully someone can provide some answers as to why doing it this way sounds better.

 

I found this supply for the raspberry.
http://www.audiophonics.fr/en/hi-fi-power-supply/linear-power-supply-double-2x-12v-2a-p-10885.html
Any thoughts if this is a good one?

 

I am going to be testing out budget/mid fi solutions to see if I can hear any differences. Currently, I am running PC to Wyrd to Bifrost 4490 to Valhalla 2 (listening with slightly modded HD650). Depending on who you believe, my system may or may not be good enough for any of this to make a difference.

PC (USB) -> Bifrost -> Valhalla 2
PC (USB) -> Wyrd -> Bifrost -> Valhalla 2
RPi3 (USB) -> Bifrost -> Valhalla 2
RPi3 (USB) -> Wyrd -> Bifrost -> Valhalla 2
RPi3 -> 503SPD1/503SPD2 (BNC/SPDIF coax) -> Bifrost -> Valhalla 2
I might do some testing on my YJ Blue TPA3116/Energy RC-10 speaker setup, but I only use it 10% of my listening time so probably wouldn't notice changes as much.

I do plan to build a couple linear power supplies and box up the RPi3 nicely at some point (which in theory will increase performance), but that takes the investment from sub-$100 to almost $300, which I consider getting out of budget fi range. The only thing I wish I had on hand was a sub-$100 USB to SPDIF adapter to test, but I don't really want to pay for one. I am not sure what to expect, as I don't have as discerning ears as others on this forum and others. At the very least, I am excited to have the RPi3 as a streamer just for gits and shiggles.

 

That's exactly the kind of comparison I'd be interested in hearing about, especially from the ears of a mortal. Looking forward to it.

Can you hear any difference with/without the Wyrd between your PC and Bifrost?

 

I never did a proper comparison with the Bifrost 4490 (have only had it for a few weeks). I originally got it to kill some noise that was getting through to an old USB DAC (which it did), so I have used it "just in case" ever since. This is a good time to finally do that comparison.

 

I'm wondering which side of the RPi3 the Wyrd should live? One might argue the little computer would benefit more from the clean power, then just the USB signal out...

Unless you have some kind of upgraded power supply in place already?

 

Interesting point. I had read that the Pi USB subsystem was a little weak (not sure if RPi3 fixed things), so I was trying to minimize its effects with the Wyrd. I suppose cleaner power on the front side for the Pi could also offset that. I might bite the bullet and build a couple LPSs to remove power from consideration and only look at everything from a digital processing standpoint. Need to sell my Vali 2 to offset the LPS costs first, though.

 

In the absence of more experienced feedback, It is not bad for the price since it is assembled in a case. But the lt108x LR family is quite old and doesn't boasts particularly good specs by today "audiophile" standard for digital circuit. Take a look at the datasheet and see that the ripple rejection in the whole audio band and beyond. There are better things (analog devices ADMseries, the TI TPS series, the linear tech. I and Scott Kramer bought, etc.), but that psu should definitely be better than the typical wallwart smps. None of the better choices is already assembled in a case or cheaper than the psu you linked.
My opinion, your wallet and choice