PCM2704 Sound Card for VoCore

qiqiji
 
Posts: 14
Joined: Wed May 06, 2015 1:31 pm

PCM2704 Sound Card for VoCore

Wed May 20, 2015 11:51 am

I made a PCM2704 Sound Card for AirPlay Server with VoCore

Good thing: it works, AirPlay works too..
Bad thing: when i enjoy music, i hear noise too.. :(

It seems noise begins by the time WiFi is on
i try wget some files ( heavy WiFi transition) noise get worse, When i turn off WiFi, noise gone too..

Need to be fixed..

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qiqiji
 
Posts: 14
Joined: Wed May 06, 2015 1:31 pm

Re: PCM2704 Sound Card for VoCore

Wed May 20, 2015 12:15 pm

Case size missed 0.5mm each side, can't fit :? but this is nothing, easy to fix~

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netomx
 
Posts: 6
Joined: Thu Feb 19, 2015 9:26 pm

Re: PCM2704 Sound Card for VoCore

Thu May 21, 2015 1:07 am

A cap could work?

Endat
 
Posts: 44
Joined: Mon Feb 02, 2015 6:29 pm

Re: PCM2704 Sound Card for VoCore

Thu May 21, 2015 2:38 am

Hey, that's pretty awesome :)

Sounds like just some interference.. I think some shielding or an antenna replacement would help. Analog sound is prone to interference.. a good example is, my desktop speakers.. they pick up radio stations.. so I leave them off.

deshipu
 
Posts: 21
Joined: Wed Nov 19, 2014 5:10 pm

Re: PCM2704 Sound Card for VoCore

Thu May 21, 2015 7:59 pm

This really looks like some very slick and useful device! Great work! I'm sure you will figure out the noise thing, can't really suggest anything apart from trying to shield random parts, or trying thicker traces on the pcb and/or having them greater distance apart. Perhaps a ground fill would help too...

Vonger
 
Posts: 839
Joined: Sun Oct 19, 2014 6:00 am

Re: PCM2704 Sound Card for VoCore

Fri May 22, 2015 1:15 am

It is easy to fix, just make the memory buffer bigger, make it to 1MB or 2MB, it might delay 2~3 seconds to play, but will avoid noise from unstable wwan.
VoCore is not optimized for mass data transfer due to its small size, so software part buffer is necessary.

qiqiji
 
Posts: 14
Joined: Wed May 06, 2015 1:31 pm

Re: PCM2704 Sound Card for VoCore

Sat May 23, 2015 3:08 am

Vonger wrote:It is easy to fix, just make the memory buffer bigger, make it to 1MB or 2MB, it might delay 2~3 seconds to play, but will avoid noise from unstable wwan.
VoCore is not optimized for mass data transfer due to its small size, so software part buffer is necessary.


Sadly, it's a hardware issue, i think this kind of ground noise is current noise because of electromagnet interference or something like that.

1, I used a well-made USB PCM2704 Sound Card with no this kind noise at all. (i try wired my card long-distance from vocore no luck )
2, Noise began at snd drivers recognition, getting worse when WiFi being initiation, before any music(or sound) played yet.
3, Try madplay some mp3 file with noise too( not worth to try because point 2)

So it's clearly not a soft issue by driver( See point 1) or Shairplay software ( See Point 2 and 3)

Still working on it.

qiqiji
 
Posts: 14
Joined: Wed May 06, 2015 1:31 pm

Re: PCM2704 Sound Card for VoCore

Mon May 25, 2015 8:58 am

update:

noise is due to wifi has been confirmed

when PCM2704 is near RT5350 about 40-50mm , noise began..
moving away , noise gone, moving closer, noise getting worse..
turn off WiFi, noise gone, turn on WiFi, noise back..

i have no idea how to fix this

Endat
 
Posts: 44
Joined: Mon Feb 02, 2015 6:29 pm

Re: PCM2704 Sound Card for VoCore

Tue May 26, 2015 6:39 pm

Endat wrote:I think some shielding or an antenna replacement would help.


^ maybe remove blue onboard antenna, and use external antenna like on VoCore 0.5

Image

Endat
 
Posts: 44
Joined: Mon Feb 02, 2015 6:29 pm

Re: PCM2704 Sound Card for VoCore

Thu May 28, 2015 8:27 pm

...Or you could redesign it so it could be mounted with the antenna/cpu facing OUT

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