Raspberry Pi I2S to SPDIF Hat

Please use a standard USB Pi supply and let me know what the results are. I personally tested all of these, so I would have noticed this. But, I used a USB supply to the Pi. I did not test the external input so it is possible something is wrong with the circuit. Although we have used the circuit before, maybe we missed something in building these protos. For now I suggest all testers proceed with caution using external power.

Cheers,
Michael

 

Hmmm, tried with a standard pi usb supply and computer usb power, no changes. Was using a piA+, swapped in a pi3, even tried removing the jumper and dual powering it--> no change.

@Mban the LPS I'm using is a dual LT1085 based one, use it all the time while testing and listening at my desk w/pi's.

Sounds like mine is a one off fluke, as long as they are not all doing that!

 

My testing board is working fine, using either Pi power or the external 5V (remove the jumper). It worked on both Pi 2 and Pi 3. And the on-board WiFi of Pi 3 is compatible to the SPD2 board. I even stacked an adafruit 3.5 inch touch screen on top of it without any problem. It doesn't have enough space to stack on top. I used an extension cable. I have no clue about the high pitch sound.

 

Usually a noise like this indicates an overloaded power supply, including on-board ones. Since you still get it when you run the pi via USB, it is a possibility that there is a short on one or more of the GPIO lines causing the Pi switching supply to be overloaded. I wonder if something happened when you ran the board from the Schiit DAC? What direction are the signals that you brought out from the Schiit?

In any case, what's done is done and I have no more boards to send. I will have some early production (25 or so) units middle to end of January, so we'll get you a new one then.

Cheers and Happy Holidays to all!
Michael

 

I'm *extremely* careful with the Schiit i2s, it's unbuffered & flapping happily out in the breeze (even leave the jumpers on for protection), and yes it has USB i2s out also... sure not gonna jam that into the 502 but even that is low voltage & idle without usb plugged in.

Seriously though, when I first got it noticed this right away while setting it up (nothing plugged in but power). Figured it was my dimmed overhead lights causing it at the time!

Poked around at the board a bit today, discovered the pitch changing and even stopping when I pressed on this capacitor near the PCM5122 chip: (prob need iem's & a bit of volume to hear it, believe me though it's actually really loud) Note: at the beginning of the clip you can hear the pitch changing, that's me starting and changing tracks.



Bad cap or cold solder joint, red herring to another problem? What do you think, could you check that out for me? Thanks!

Edit, leaning toward cold solder joint, seems to improve for a bit after pressing on it.

 

I would definitely check, if I had any boards left! Hopefully if anyone else spots this they will let me know. This was certainly part of the reason to send these out. Give them a good thrashing!

Cheers,
Michael

 

Thanks, I did edit that post a bit... is that just a bypass cap? I can probably trace it if you are busy.

Have a great holiday & New Year!!! Thanks!

 

It's one of the charge pump/internal regulator bypass caps. I suppose it could be bad. It's 10uf/16V, 0805 package. I suppose it can;t hurt to try!

Cheers,
Michael

 

OK, I'll flux it & flow some new solder on that part. If it's still bad I can send it to you to debug if you'd like!

 

Yes, please sen it back if it still acts up. Hopefully I can diagnose and fix it.

Cheers,
Michael

 

I heard the buzz sound today, however in different situation. It was quite obvious, surprised. It was not always there. I connected a Pi 7 inch official LCD to the Pi 3 running piCorePlay with Jivelite. The buzz started only when I "turn off" the squeeze touch interface (the power switch icon on the upper left corner of the screen). The unit did not turnoff, instead, the screen dimmed. Then I heard the buzz sound. The buzz went away after I click the power switch icon to "turn on" the squeezelite Jivelite.

 

Can you take some photos of how it is all connected?

Cheers,
Michael

 

Is that a no on the photos? Also does the noise occur when you do not have this display attached? I really want to figure this out and honestly, that was the point of sending these out. Maybe your just in a food coma from the holidays!

Also, what about the rest of you guys?

Cheers,
Michael

 

I pulled that cap... it measures 10.11 uF and 9.90 Meg ohms (was hoping for a dead short). No change to the board noise resoldering it, or removed completely.

 

Well, that sucks! I just sent off the re-spin and will have more for testing end of January. It will simply have to wait until then to see if this is a one-off or something else. As I said, I tested all of these and had no inkling of this. Probably my ears are too old to hear it. My new dScope should uncover it pretty quickly and allow us to fix it. Either that or I drag my 17 yr old son in to give it a listen!

Cheers,
Michael

 

Ok cool, can you hear it in the vid? It's high freq, but not dog whistle high! Also just an fyi I noticed when testing on a pi3, the bnc and xlr solder connections are crazy close to the ethernet/usb metal housings... it even cut out as I was plugging in the bnc putting light pressure on it.

 

I should have supplied you the normal 18 mm standoffs that we use. If you put the card in seating the connector all the way it ends up about 16 mm. The 18 mm gives it just a little bit of margin so that you don't have those mechanical issues. We do supply the standoffs with all our boards, but I did not for this project. Sorry about that.

Cheers,
Michael

 

Hi Michael, Sorry for the delay. I have been making a case for it - I like it so much that I think it deserve a good box. I will post photos and my second report. It also take some time to have friends listening in my system as well as bring the unit to their system. Will post in a couple of days. It is all good, excellent in deed. BTW can someone enlighten me how to post images as an attachment? I try to avoid other online photo website. Thanks.

 

@hifiandrun - imgur.com is a free and easy way to post photos.

 

Only "friends" can post images. I like using google drive