Raspberry Pi I2S to SPDIF Hat

Michael,
If I am reading the specs correctly, the Pi2AES hat itself only uses about 80 mA with a 12 V input voltage (i.e. 1W max). Apparently, most of the time it would use about 20 mA. Most of the power requirment comes from powering the RPi. If one was to separately power the RPi, you could use a pretty low power PSU for the Pi2AES. Maybe even a battery.

Am I missing something?

 

Sorry about that. Also the top has the pi2design logo.

Michael

 

No worries. By the way, the bottom on mine has the logo too. I thought that was a little strange, but no big deal.

 

So of course you got the one unit where I screwed up and etched a bottom!

Cheers (and apologies),
Michael

 

Michael,

Can you confirm my power supply calculations? That is, the Pi2AES itself uses a max power of 1W. At a 12 V input, 1W/12V = 83 mA. I am asking because, if I choose to build a linear power supply for 100 mA @ 12V, I can get away with a transformer that I already have in the parts bin. But, if I plan on powering both 83 mA hat and the RPi 3 at 700 to 1000 mA, the load regulation of the transfomer forces me to a higher voltage. Given that choice, I will probably try powering the hat alone with a linear supply and use the good old RPi switch power supply for the Pi.

Thanks in advance.

Jac

 

According to the bench power supply that I use for testing, it draws less than 60 mA at 12V. Remember that it can accept up to 48V with a corresponding decrease in current.

Michaell

 

I did something similar with a Digi+ Pro and it sure works.
I just added a J.S.T. connector to the other end of a short RJ45 cable and a header on the Digi. It’s hacky, but it works.
The Digi I2S are unbuffered and not meant to be tapped like that. The 502AES will perform much better.

 

Ok. Just switched configuration to separate power for Pi & hat. Pi is powered by an Illuminate v3, the hat is powered by an LPS 1.2. Quick impressions are: detail (micro / macro) is slightly improved over a single Illuminate v3 powering both. Background is slightly blacker. Voices have a bit more 'solidity'; bass notes are full and textured. Might actually be a bit much with cans with a 'U' shaped presentation (Verite is eating it up - don't remember which pads I have on, Empyrean is a bit too much in the bass / mid-bass).

Disclaimer: Honestly, it's sheer lunacy to power a $149 hat with ~$2k worth of power supplies. I am because I have them, and I'm very interested in how these Pi/HAT streamers scale. It'd be of more general interest to see how this new hat compares to the DigiOne sig when powered by more cost effective power supplies. I'll leave that to others, as I'm going to use the best power I have.

Does it seem to scale fairly well? Yes, yes it does. Has it replaced the DigiOne Sig in my chain? Yup. It'll take a more in-depth comparison with Sig to see which one ultimately eeks out a sonic win, but the performance I'm hearing, with the lower price and support for AES (and possibly I2S with Pavane) leads me to give it the edge.

 

@MisterRogers God damn you. But thanks

 

Hey, it's not like I'm using an Af as a preamp for a 3F. Now THAT'S insane, right @jexby?

 

So because I'm an idiot, what are the power specs for the Pi and AES HAT again? What is their voltage tolerances/range? Will need to figure out a LPS solution.

 

The PI wants 5V (actually better to have a bit over like 5.2V) at 2-3A and the PI2AES wants 12V to 48V, current of <60ma @ 12V, lower at higher voltages.

Cheers,
Michael

 

Thanks Michael. Sounds like if I get a supply that can do dual-output at 4A combined, I should be covered.

 

Yes that should work fine.

Michael

 

A single quality supply at 12v, ~4A seemed to perform very well. YMMV.

 

Worst case I could use the SMPS from Allo to power the Pi side as well, which is actually a good unit considering the minimal cost.

 

The recommended current for the Pi (and that supplied by its standard switchers) is 3A or so, but that's to account for anything else it might be driving (screens etc.). The current draw of the Pi alone is minimal. I'm powering a Pi & HiFiBerry Digi+ with a 1A linear wall-wart with no issues. Whatever 5V supply you have will be fine.

 

What a coincidence! Turns out the PI2AES uses the same SW driver so you could drop it in and get even better sound! Just saying.

Cheers,
Michael

P.S. HifiBerry is a great company so I am only joking, mostly.

 

fyi: HifiBerry: diyaudio--> 10
Also Allo has done great work building on these original drivers, it's all in GitHub to see and they communicate about it while developing.