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Chord Poly / Chord 2go equivalent with a Raspberry Pi?

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#1
It's my first post on ASR, I've been a long time lurker. I'm amazed by the community on here, and figured some of you guys might be able to help me with a project.

I intent to build an equivalent of the Chord Poly / 2go streamers using a Raspberry Pi Zero W, hooked to an E1DA 9038S via the onboard micro-usb of the Pi. I'm not too interested in the streaming part of the Poly / 2go, but I highly like the possibility to use it as a portable screenless player with a micro-SD card on which to plug my headphones and control it with my phone. I did not buy one because I don't care much for boutique products, and I've been very happy with my E1DA 9038S gen3 plugged into my phone.

The idea arose that I could design a device that would provide the same function as the Poly-as-screenless-player, and that I could do it with a low consumption microcontroller such as the Pi Zero W, which only draws about 80mA when idle. I would make the Pi into a Roon endpoint, add a second Micro-SD slot to expand its memory to 512go, put my music collection on there, and use an app on my phone to access it remotely by having the Pi connect to my phone WiFi hotspot.

I did preliminary research, but ended up running into informations that might compromise the feasibility of my project. As I intend to have the Pi run on a battery pack (LiPo battery), it seems like the proximity of the E1DA 9038S and the power supply of the Pi might create unwanted noise that would end up in the signal running into my earphones. I have asked around but never could get a clear answer: is there a way to shield the PSU from the DAC? Will the DAC balanced output solve my issue on itself, filtering the noise before it reaches my ears?

The end device, if it were to work, would be able to play continuously for up to 8 hours, hold up to 1to of music. The most exciting part of this project is the design. I'm a design and visual arts major, and designing the case, the look and feel of it from the ground up is the most exciting part to me. I have a lot of ideas on how to improve the usability and practicality of such a device. Anyway.

If any of you have any kind of experience with something analogous to my project, or would like to present his/her musings about electromagnetic interference, shielding, the back digital noise of the Pi board, any help would be more than welcomed!
 

somebodyelse

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#2
The basic idea is plausible, but I think some of the specifics you outlined won't work as intended. There are alternatives though.

So far as I know you can't run the server part of Roon on a Pi, let alone a Zero. If you ant to work standalone I think you'll need something else. Logitechmediaserver (LMS) might work - I know PiCorePlayer works on the Zero-W, but I'm not certain it will let you install LMS on there too. You can use one of the phone apps to control it, using one or other as a wifi hotspot.

I'm not sure how you were intending to add a second µSD slot, but I guess it would have to be via USB and a hub. There are some hubs built to stack with the Zero - you might find one with battery power and/or card reader included if you're lucky.

If I've understood the 9038S thread correctly the interference is usually from the phone's intentional RF output, not incidental emissions.
 
OP
whaleboard
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Thread Starter #4
The basic idea is plausible, but I think some of the specifics you outlined won't work as intended. There are alternatives though.

So far as I know you can't run the server part of Roon on a Pi, let alone a Zero. If you ant to work standalone I think you'll need something else. Logitechmediaserver (LMS) might work - I know PiCorePlayer works on the Zero-W, but I'm not certain it will let you install LMS on there too. You can use one of the phone apps to control it, using one or other as a wifi hotspot.

I'm not sure how you were intending to add a second µSD slot, but I guess it would have to be via USB and a hub. There are some hubs built to stack with the Zero - you might find one with battery power and/or card reader included if you're lucky.

If I've understood the 9038S thread correctly the interference is usually from the phone's intentional RF output, not incidental emissions.
After some research, it seems like a DietPi setup will be the most fitting for my use case, it should work without an issue.

You can add a second SD-Card slot on the Pi Zero W using the SPI method. It allows to switch cards while the Pi is working.
https://ralimtek.com/raspberry pi/electronics/software/raspberry_pi_secondary_sd_card/

That's great! It means the 9038S won't be bothered by any kind of EMI.

Now my only concern is regarding the Pi Zero USB port's cleanliness. By according to Archimago, the USB ports on any Pi are clean enough to plug in any DAC and not hear any difference.
http://archimago.blogspot.com/2018/12/measurements-intel-i7-pc-and-raspberry.html

Why do you want to power it with a battery?

is this for a wireless speaker project of some sort?
I want it to be a screenless, portable music server. A music player that outputs via the 9038S USB DAC/AMP but that can be controlled via phone. Exactly like the Chord Poly / 2go.
 

somebodyelse

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#5
You can add a second SD-Card slot on the Pi Zero W using the SPI method. It allows to switch cards while the Pi is working.
https://ralimtek.com/raspberry pi/electronics/software/raspberry_pi_secondary_sd_card/
Thanks - wasn't aware of that option for the Pi
That's great! It means the 9038S won't be bothered by any kind of EMI.

Now my only concern is regarding the Pi Zero USB port's cleanliness. By according to Archimago, the USB ports on any Pi are clean enough to plug in any DAC and not hear any difference.
http://archimago.blogspot.com/2018/12/measurements-intel-i7-pc-and-raspberry.html
[/QUOTE]
You might want to check these on the 9038S thread or on their Discord - more reliable than me dipping into it from time to time and maybe misunderstanding. They'll have more experience of things like Y cables to give the DAC cleaner power if necessary - I think they're usually used for phones that can't power it directly.
 
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