Raspberry Pi I2S to SPDIF Hat

According to Michael's hw_ref_manual on his website, my understanding was that any power input directly plugged in the 2.5mm DC power socket on PI2AES will first go through a over-voltage protection circuit/chip followed by a DC-DC converter to get the 5V DC power for both the PI2AES board and the raspberry PI. The DC-DC converter is essentially a switching circuit. The DC output between 12-48 V from any expensive LPS power supply will still have to pass through the DC-DC converter circuit. Would a clean-feed power to the DC-DC circuit yield a significant better sound? I doubt. Changes of sound signature? may be or may not.

Now here is the real itching question: what happened if we bypass the onboard DC-DC circuit and use a fancy 5V LPS for the PI2AES and a separate less-critical 5V DC for the raspberry Pi? After I understand that this would void warranty of the board and it was highly possible that I could fry the board (no over-voltage protection at all), I took the risk and tried the following. First, remove the black jumper (W2) on the upper-left corner of the board (left to the three LEDs). This would disconnect the 5V+ power supply from the PI2AES to the underneath raspberry Pi. Now the Pi can be powered by its usual way. Second, power the PI2AES board from the pin 2 (5V+) and pin 3 (ground) on the expansion header alone the left side of the board. The PI2AES only needs about 20 mA of 5V based on the reading of a cheap meter, which shows 10mA for Allo DigiOne Signature. Note, any LPS with an output voltage > 5.5VDC could potentially fry the PI2AES in a second connected this way.

I think I may heard a little different sound signature. The LPS-powered PI2AES (bypassing the on board DC-DC circuit) is a tad warmer. YMMV. I only tried it briefly for my curiosity, and I ended up using my $17 voltage-variable 3A switching PS from Amazon.com, which also avoided clusters of wires and the PI2AES sounds just fantastic.

 

Order placed, fwiw, the Paypal checkout was a never ending cycle, referred to Paypal, returned to pi 2 design, re referred to PayPal and on and on, beck and forth, never getting to "complete order", found my wallet and purchased ith a card.
update: just received an email from PayPal asking if I wanted to complete the purchase and a link was provided to return to merchant. Well, it has sent me back to the merchant twice already, so I guess this is paypal's fault.

 

I made a purchase of the PI2AES Monday evening using PayPal and no such issues were present. I guess it was a temporary issue.

 

OS/Browser shouldn't matter anymore, but they do. On macOS, I occasionally need to use Chrome instead of Safari for eCommerce transactions.

 

That sounds like some session/cookie problem to me. Easiest fix is switching browser or going incognito.

 

I see that moode has released their 6.1 which is a release after they started supporting the raspberry pi 4. If anybody has experience with it I’d love to hear. I will be testing myself in the next day or two to see if we can officially declare support for the raspberry pi 4. At least using moode.

Cheers,
Michael

 

Thank you for reporting on your experiment. I suspected something like this was true and, yes, the Pi2AES sounds very good, even with a switch supply.

Of course, I just finished assembling a nice quiet LPS for the Pi2AES, but maybe I don't need it.

One thought comes to mind. If I understand correctly, switch supplies are not very efficient at low duty cycle. Leaving one on all the time with the Pi2AES taking 20 ma might qualify as low duty cycle for a supply rated at 1 amp (my currently used switch supply). My LPS is a very efficient design. I wonder which will make my electric meter spin faster?

Jac

 

I just bought the PI2AES with an RPi3 and the stock power supply. I have Allo power supplies that I can use on the DigiOne Sig as a "stock vs stock" affair. I also got a starlight 8 AES to match the BNC cable I already have.

This will be cool to test the different input capabilities of the Metrum Onyx using the Pi2AES, but also to compare the BNC-out of each streamer device.

Both are seeming to be very capable units and frankly I predict the results to be less than exciting or dramatic haha.

 

Hi Jac, when I used the switch power supply, it was the common set up - e.g. to power both the PI2AES hat and the raspberry Pi. The raspberry PI 3B alone would draw at least 0.5A - 1.0A at idle. If the PI also connected with a usb-HD drive or with a 7 inch Pi display, more power will be drown. Thus I guess no need to worry about low efficacy using switching PS, although it’s just my guess as I don't have a professional EE background.

Michael's design uses expensive LT3042 regulator for the two critical ultra-low-jitter clocks. I would think this is one of the reasons as to why the PI2AES board isn't picky on power source. By the way, when use a nice LPS 5V with the onboard DC-DC circuit bypassed, the 5V will still go through and further smoothed out by the LT3042 regulator. Happy listening.

 

I just tried the moode 6.1 on a rasPI 4B / 4G RAM with a PI2AES. It works. Music from a USB HD drive directly connected to the Pi 4. I did not compare the audio quality with my LMS setup. I've been using the LMS for many years. The Moode uses MPD. So far, the Moode is convenient and easy to use.

The PI4 runs hotter. The biggest advantage of using the PI4 over an older Pi3 is the improved USB (USB3 on Pi4) and the separated Gigabit Ethernet (did not share thus limited by the USB2 PHY populated on PI2 and 3). It is almost mandatory to use one pi for music server and another one for music playback when use Pi 2 or Pi 3. The Pi4 makes putting the server and the player on one Pi possible without losing audio quality.

 

Thank you for the info!

Michael

 

I can now confirm what hifiandrun reported, Moode 6.10 on a PI 4 (I have a 2GB model) runs flawlessly. I tested all interfaces and they work.

I will need to make a new case design (just changes two sides) and should have that ready for Tuesday (Monday is a holiday in the US).

Question - Should we ship the two PI 4 case panels with every case order, or should we have the customer specify they want them? I don't have any idea on what the usage for the PI 4 will be. I also think we will offer just the two panels for a few $$ plus shipping for anyone who wants to upgrade.

Cheers,
Michael

 

Still running PI2AES with Pi side powered by a quality LPS and hat powered by an LPS 1.2. Couldn't be happier with the sonics I'm hearing. I haven't had time to do a more detailed A/B of PI2AES vs. Signature - or to wire up PI2AES into Pavane I2S, but I believe PI2AES to be a better value vs. Signature by no small margin.

Thanks for your efforts here Michael - I hope to provide more data points soon.

 

I haven't followed along in a while, but I am setting up my 502DAC now and want a case. I don't remember if I asked or it was answered a while back, but @Michael Kelly would you be willing to share your drawing files for the acrylic case so I could get some different materials and colors cut?

 

I have uploaded the files to our dropbox and here is the link:

.dxf
https://www.dropbox.com/s/pyy8wflszxm1o41/502dac_case_12_18_p5.dxf?dl=0

.svg
https://www.dropbox.com/s/5qdz0etpbw5kiyj/502dac_case_12_18_p5.svg?dl=0

It is a multi-up to build 3 cases at a time on our in-house laser.

Cheers,
Michael

P.S. I will post the PI2AES shortly now that I have updated the design to include the PI 4.

 

PI2AES on PI4 in case:

OK, decision made. We will supply the two PI 4 specific panels with every case order. That way folks can upgrade later if the choose to.

Cheers,
Michael

 

Any chance folks who already placed an order (but haven’t shipped yet) will get em?

 

Yes. And anyone who wants them even after ordering just has to pay the shipping (assuming you ordered a case originally). We'll be adding it as an item in the store for that purpose. Probably list as an upgrade so folks don't think it's the complete case!

Michael

 

Hi All, just a quick update on Pi 4B support. I briefly tested the piCorePlayer 6.00 beta 1 with the Pi 4B board. It worked fine as a LMS player using wired LAN connection. Extra functions such as expanding the image size or using wifi instead of wired connection were kind of little buggy. The 6.00 image includes files for both Pi 1-3 and Pi 4 thus the default image is larger then the 5.00 version. (64MB, but hey it is still just 6.4% of 1 GB.) The image size would need to expanded if you want install the LMS server, Samba, etc.
Note that the 'Hifiberry Digi Pro" option on the squeezelite tab will not show up on the "normal" tab page, but it will show up on the "beta" tab page. Here is the forum page and the download link. I will not go into details as this is the PI hat page.
https://forums.slimdevices.com/showthread.php?110727-BETA-piCorePlayer6-0-0-PI4-support

 

Full disclosure, I only tested Moode 6.10 with wired ethernet and an attached USB drive. I was looking for confirmation that the PI2AES worked on the PI4. So, there may be issues with Moode 6.10 as there seem to be with piCore Player.

Cheers,
Michael