Raspberry Pi I2S to SPDIF Hat

Could not agree more! USB on the Raspberry Pi will always be a compromise. Not because USB2.0 does not have the raw bandwidth for audio, heck not even that it is shared with Ethernet on the Pi (though that totally does not help). No, it is because the Pi runs Linux, a non-real time, non-deterministic OS. Linux is filled with so much junk code it is sometimes amazing it runs at all. It is truly the embodiment of the joke about an infinite number of monkeys writing Shakespeare! For USB audio, the Pi3 does a better job simple because it has a bigger hammer to smash the code into submission. But, using I2S, the humble, 800Mhz single core B+ will work as well as the 1Ghz quad core Pi 3. My biggest recommendation if you use the Pi for audio, is to only use it for audio. At $35 you can always get another! Web surfing, video decoding, SD Card writing, all can impact even the I2s, though much, much less than the ridiculously complex USB layers in Linux. So many of the USB issues such as dropped sync, weird popping noises, etc are very likely due to the OS dropping data to the USB. Remember, USB audio data does not get re-sent, miss a frame and it's gone!

Rant over!

Cheers,
Michael

 

I'm glad the you'really carrying on with this project and look forward to hear the speed. I'very been positively impressed by the 503dac1. There's nothing to be sorry about. It's not your fault. Italian customs (and beurocracy in general) slowness is proverbial here

 

MIchael, what would you say is worse for audio, Linux or Windows? Right now I am getting ready to compare different audio players on the same machine but running Lubuntu versus Server.

 

It is less about the OS than the power of the CPU. If it is a PC then most any system will do that is not a low end netbook. As I mentioned, the USB layers and the lack of real time determinism is the issue. On a Pi there is not enough horse power to overcome all issues, but on a typical PC there is.

[EDIT] this is referring to USB audio only, not I2S.

But remember, this is my opinion based on some experience and reading what others say they have found, but not exhaustive testing.

Cheers,
Michael

 

No Worries. Always have to feed yourself first. Thanks for the attention you have given this community. Look forward to testing!

 

@Michael Kelly Any news on the builds? I noticed everything died down on this thread, so just bubbling stuff up.

 

Just the usual product development stuff. PCB's came in and parts all arrived, but a key piece for the assembly process, the solder paste stencil, came in backwards! Now I have to wait a week for a new one to come and get on our machine. Sorry to keep you all waiting!

Cheers (or is that boos),
Michael

 

Take as much time as you need. You only get one chance to get it right the first time,

 

What I'd the price for these builds?

 

Extremely reasonable would be an understatement.
http://www.superbestaudiofriends.or...ry-pi-i2s-to-spdif-hat.1990/page-2#post-50564
"Like Digi+ we'll offer with and without transformer versions. Price will be $39 without and $49 with." Only the hat, not including the Pi

 

How much will this be in Europe or does it have to be imported?

 

@Vastx and @Scott Kramer . I am figuring out how to power the HAT first and then the Pi. What would be the options to achieve this?
Investigating some PSU options but seems rather limited here is Europe. Any links as where to look?

 

@Eugene du Toit
How much DIY? These kits are almost ready and are In France.
http://www.audiophonics.fr/en/linear-regulated-psu-c-6305.html?orderby=price&orderway=asc
Take a dual rail lt1083 and save some money
http://www.audiophonics.fr/en/linea...y-module-double-dc-lt1083-20v-75a-p-8426.html

If you can solder and can wait, these are kits from China but are more expensive.
http://www.diyinhk.com/shop/audio-k...e-dac-power-supply-regulator-33v55v-1ax4.html
http://www.diyinhk.com/shop/audio-k...e-dac-power-supply-regulator-3357v-15ax2.html

Or make something Better ang get a Salas PCB from DIYaudio.com. This one is too much hassle for me.

In any case I would advise against spending big money.

 

I have built some DIY amps and speakers so I can solder. I was not planning to spend much money on it, more of a experiment.
I also found the ifi iPower 5V which could be good option, but reviews are far and few in between. I think the cost is about 60 euros, and unlike those linear PSU comes in a small package. @Vastx Nice options you gave there thank you. How is your PSU connected to the Raspberry? According to @Scott Kramer there is big benefits to powering the Digi+ first which then feeds the Raspberry.

 

I agree, I feel like feeding directly the digi+ through the gpio is better soundwise. It's not something I A\B'd but over the weeks It just felt better. Also Scott advised to feed the 3,3 directly to the digi+. I did it and I found improvement.
If you don't have the digi+ yet wait for the speed1\2. Judging from the 503dac1 I tried It is gonna be worth. It already sounds better than the stock Digi+ and though I slightly prefer the modded digi+ softness no one that has heard them in my house agrees with me

 

@Vastx I allready have the Digi+ and Digi+ Transformer version. Could you show me with a picture how you are feeding the Digi+ directly? I am trying to see what kind of adapter I have to buy to do so.

 

I already gave information about it here:
http://www.superbestaudiofriends.or...ap-transport-that-made-me-happier.1970/page-5
The 2 pin white connector I used for the 5V was desoldered from something like an old VGA.

 

The current group buy for the Reflektor-D digital PS boards/kits is ending soon (June 26th) if you want one: http://www.diyaudio.com/forums/group-buys/258340-gb-salas-reflektor-d-power-supply-digital.html

If you want to push higher current through a Reflektor-D (e.g. 1 amp), I would recommend sinking the mosfets and rectifiers in the build to a sufficiently big heatsink(s). Also don't forget to electrically insulate them from the heatsink so there is no shorts (e.g. use thermasil III pads, etc.).

 

Looks interesting. Have to study it a bit and see if I can do it.

 

would I need 2 of these one for the pi and the other for spdif?

weighing my options and pi solution is probably the best transport (without breaking wallet) when its done.