Raspberry Pi I2S to SPDIF Hat

The header pinout is fine, but it looks like my RJ45 footprint is wrong. I have pin 1 on the right when facing the front with the key down, but it should be on the left. Not sure how this happened, but I need to remake the boards. I will jump on it asap and send replacement boards out as soon as I can.

Michael

 

I plan to feed the Pi2Aes to a Modi 3 (via coax) .. digging a bit back in the thread, it appears the preference was to use the BNC->coax vs the SPDIF out, right? If so, is it ok to use a cable like this or should a BNC-to-Coax adapter be used?

 

A cable without any adapters is always preferred. As long as it is 75 ohm impedance you can’t get any better.

Michael

 

I had an issue i2s initially, was a bad board. Replacement and subsequent purchases all work perfect.

 

Just while I remember: is there any isolation on the i2s in the way that there is for the other outputs? I read somewhere up thread that part of the i2s output is from the pi and part from the PI2AES board but couldn’t see if that meant the output was electrically isolated from the pi or not. Thank you.

 

It is not isolated, but it is buffered. A separate chip takes all the signals and drives them with proper series termination so that they can go a fair distance. You are not connecting directly to the raw signals.

Michael

 

Thanks Michael. Is there then something about the way i2s is configured that makes it less susceptible to transmitting noise compared to the S/PDIF implementations? I'm sorry I don't know enough about it, but does the buffer mean that any noise could also then go a fair distance or is there something about it, as there is with optical, where the signal transmitted to the DAC is somehow separated form any noise that may be present in the raw signal?
(I am using 'noise' in a very non-specific way here simply to mean anything that may be present in the Pi stack that could have an effect on the DAC.)
I don't know if you aware of the Allo Isolator that they developed to provide galvanic isolation between a Pi and any DAC HAT that may be mounted on it. Since they then introduced the USBridge Sig as an ultra quiet Pi board there have been quite a number of users who decided that the Isolator was no longer necessary and possibly added latency (or somesuch). I have now gone back to using the Isolator (with Allo Katana DAC), as (in my context) I find the sound somewhat fatiguing without it.

 

Since we are talking about digital signals that need to be recovered/detected at the far end, as long as they are sufficient for that process, than any other "noise" is irrelevant. In my opinion the use of an isolator for digital audio transmission is a waste of money.

As to sound quality, if you have setup that pleases you, stay with it and spend your money on the music!

Regards,
Michael

 

@Michael Kelly Any update on if you have a Pi4-compatible case? I placed an order last night, LMK if I should reach out and request a Pi4-friendly case.

 

The case set up is included with two extra pi4 specific panels, one for the front where the USB and ethernet are and the right side where the two HDMI connectors are. They are marked with a “4” so you know which ones to use.

Michael

EDIT - Only the PI2AES has the PI 4 compatible case panels. The 502DAC does not.

 

Quick cable write-up for the Pi2Aes. Tested various cheapish cables with the AES output of the Pi2EAS and found the Pro Co 6' Premiere Canare to sound the most transparent/cost effective with the Yggdrasil A2. BlueJean cable (s) are pretty good for the Bnc/component connection, the best but expensive are the Oyaide Digital Cable BNC. For i2s, all the Hdmi cables tested sounded the same, just bought the shortest one. If anyone has a good hdmi cable to try, let me know.

 

ref: https://www.superbestaudiofriends.o...pi-i2s-to-spdif-hat.1990/page-109#post-279258

Stock Pi2AES will work fine, but you'll have to do the annoying 44.1/48x multiple manual switch on the C2 if in master clock mode. Also it probably recovers the clock even when master/bitclock in-- ie minimal sonic changes, however:

My modded PSAudio on the other hand, I removed a XO (the 192 crystal) and wired that coax straight in... and did some logic setting the internal upsampler/pll to BYPAS & not recover the clock-- still, maybe the C2 does that (bypass the clock recovery pll), thought it'd be fun to try.

 

So I received the Pi2AES (w/ stock power supply) a few days ago and wanted to report a few meaningful differences I'm noticing between it and the DigiOne Signature (w/ battery pack and allo stock psu). Also, take all this with many grains of early impression salt.

First, my DAC is Yggdrasil A2, and each transport is utilizing its best output - Pi2AES feeding AES and DigiOne Sig the BNC.

Prior to the Pi2AES, I attributed the slightly muddy/loose sounding bass to my untreated room. Well, while the room still needs work, the most immediately noticeable improvement Pi2AES brought to my system was in the lower registers, where bass lines sound tighter, slammy-er, and better seperated.

I wasn't unhappy with the DigiOne's bass performance, but I was surprised at how much better the Pi2AES via AES sounded there. But then I decided to test the Pi2AES via BNC on the Yggdrasil, and lo and behold, the bass sounded pretty much like the DigiOne's. So, what's likely is that I'm providing more insight into the capabilities of the Yggdrasil's inputs, with the general principle of "BNC is good, AES is better" being confirmed? Not sure that I'd switch from DigiOne Sig to Pi2AES if BNC is my best input option.

But one last conundrum, the DigiOne actually produced more relaxed/smoother sounding highs, but still seemed a tad brighter, fatiguing than the Pi2AES. At this point, I feel like I need to listen a lot more before commenting on other technicalities. Might be a testament to the quality of both transports that I don't hear much of a difference in the mids.

 

This is (generally?) true though. Here for example, jitter of RCA < BNC < AES on Gustard U16 (img source is a Chinese blog):

 

Could I ask if the DigiOne and PI2AES are on a Pi each and, assuming they are, whether you power down and/or disconnect the one you are not listening to at the time? I also have a separate Allo based set-up which I alternate with the PI2AES and I'm pretty sure (though still not 100%) that when they are both powered up there is an influence on what I am hearing which may be due to their respective power supplies, but I'm not sure.

 

Have spend a few days with the Pi2AES with stock power supply.

Previous set-up was Eitr out of my laptop.

Gear Chain:
SFD1-MKII & Gungnir A2 -> Freya S -> Mjo2 or Starlett -> LCD-X, 650, 800S

New is Pi2AES:
- Volumio OS
- AES into the SFD1
- BNC and SPDIF into Gungnir (wanted to compare)

My motivation was mostly just NO wires and easily controllable on my phone. If if it sounded great, bonus for me!

Turns out it does sounds good... maybe great. Definitely different from the Eitr.

Things I noticed:
- Resolution increase
- More defined layers and separation of layers
- Everything is more tidy, hard to explain
- Finally just more ease to listening

BNC vs COAX SPDIF on the Gunginr... hard to tell any difference.

Really enjoying my system and it's synergies right now! It all starts with the source...

Great work Mike!!! I am a very happy customer.

Best part, fun lights!!!

 

Yes, they're both on their own Pi's, always powered on and connected simultaneously to the Yggdrasil (unless I was comparing between the BNC outputs of the DigiOne and Pi2AES.)

 

I ran MoOde audio 6.4 with a RPI 4 successfully with Qobuz and UpNP, but with Pi2AES, what "I2S" Audio Device do I select? HiFi Berry? Allo DigiOne? None of that is working. Or do I need to be in some other portion of MoOde?

Here's the setup:

iPhone mConnect -> WiFI -> Pi2AES -> SPDIF -> Airist R2R DAC -> Amp -> Headphones

I had mConnect working great earlier via USB and RPI 4.


Update: refer to page 101 of this thread for the Hifiberry Digi+ Pro guidance

 

Hifiberry Digi+ Pro is what you pick in Ropieee, so I assume it is the same in Moode?

Edit: actually I use AES not i2s - not sure if that matters or not...

 

Doesn't matter what output you use, Digi+ Pro is what is used.