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Really bad audio
#1
Hi guys, 
I have a CM3 with the latest SD card image. I’m having audio issues which are happening constantly (whether I’m in game or not). Lots of chirping and buzzing, similar to what’s described in this thread:

https://forum.freeplaytech.com/showthread.php?tid=4769

I’ve turned my software volume way down in the Freeplay audio settings, and I’m still getting lots of noise. This seems to happen whether or not the system is actively reading or writing to the micro SD card (a brand new Samsung 128 GB micro SD). 

I’ve tried to eliminate sources of interference (phones, etc), and this seems to have no effect. I’m also using a Boxy Pixel shell, so I imagine that the aluminum shell would do a pretty good job of shielding it from interference anyway. I’m also having the same audio issues if I use headphones, so I can rule out the speaker itself being bad.

Any idea what I can do to troubleshoot this?
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#2
Is there any chance that the metal Boxy Pixel shell is contacting the circuit board? I think their guide mentions shielding some areas with tape and also clipping back some protruding solder joints. Maybe look into that next.
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#3
(06-09-2019, 12:13 AM)Flavor Wrote: Is there any chance that the metal Boxy Pixel shell is contacting the circuit board?  I think their guide mentions shielding some areas with tape and also clipping back some protruding solder joints.  Maybe look into that next.

No, I was having the same issue when the board was outside of the shell, sitting on a wooden table. I also used Kapton tape to prevent shorts. I wasn’t able to find the guide that you mentioned on the Boxy Pixel website. Do you know where I can find it? I’ll take a look just in case. EDIT: Nevermind about the guide, it’s here: https://www.boxypixel.com/pages/assembly...erry-pi-cm

I’ve tried setting the audio level in Alsa Mixer to 3% with the volume wheel set to high, and I’ve tried setting the Alsa volume to 80% with the volume wheel set to low. In both cases, the hissing and popping sounds were equally prominent.

I’m starting to worry that it may actually be faulty audio hardware at this point.
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#4
Okay, I’ve applied a crap-ton of Kapton (not a great joke, but not a terrible one either), especially near the audio hardware. I’m certain that there are no shorts with the shell. I’m still having the same issue though. It’s most noticeable in the Emulation Station menu, but I’m still hearing a constant whining sound, along with intermittent popping, no matter which games or emulators I am playing. It’s maddening.
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#5
You said that you turned the software volume way down. Did you try turning it way up (90-100 in ALSA) as another data point?

This stuff is very difficult to track down, and part of that is because there's always (at least in my mind) the chance that you are more discerning than other users. Do you think there's a chance that what you are hearing would seem "normal" to most users?

Most people will be able to hear noise until the system initializes the audio. Once in game, this (at least to me) is gone.

So, I want to be sure that we're talking about some issue with the hardware that's out of the ordinary (and not that your ears are able to hear stuff that many people can't notice).

Having said all that, we did (well over a year ago) have some units that had a solder issue in the audio amplifier section. As far as manufacturing goes, this issue was resolved a long time ago, but I guess there's always a random chance that a capacitor is bad or that it didn't get soldered well. Would you want to post some photos of the circuit board around the volume wheel and headphone area?

I'll talk to my colleague a bit more about this, but we may need to get you some different hardware to test. Can you open a SUPPORT ticket at https://www.freeplaytech.com/contact/, so we could try to get you some different hardware to test with?
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#6
(06-11-2019, 10:11 AM)Flavor Wrote: You said that you turned the software volume way down.  Did you try turning it way up (90-100 in ALSA) as another data point?

This stuff is very difficult to track down, and part of that is because there's always (at least in my mind) the chance that you are more discerning than other users.  Do you think there's a chance that what you are hearing would seem "normal" to most users?

Most people will be able to hear noise until the system initializes the audio.  Once in game, this (at least to me) is gone.

So, I want to be sure that we're talking about some issue with the hardware that's out of the ordinary (and not that your ears are able to hear stuff that many people can't notice).

Having said all that, we did (well over a year ago) have some units that had a solder issue in the audio amplifier section.  As far as manufacturing goes, this issue was resolved a long time ago, but I guess there's always a random chance that a capacitor is bad or that it didn't get soldered well.  Would you want to post some photos of the circuit board around the volume wheel and headphone area?

I'll talk to my colleague a bit more about this, but we may need to get you some different hardware to test.  Can you open a SUPPORT ticket at https://www.freeplaytech.com/contact/, so we could try to get you some different hardware to test with?

Yes, I tried turning Alsa volume up to 90, and brought it down one point when the volume gauge turned red.
Also, today I reflashed my SD card to the latest image (the one from a few days ago) just to rule out any issues there. I've tried a couple of different Micro SD cards.

I understand what you mean - I definitely don’t have picky audiophile ears though. I’ve noticed that it happens when data is being written to or read from the SD card. I recorded a video of the chirping happening loudly and continuously while importing files via a plugged in USB drive. I’ll try to upload that video somewhere when I get a chance. I also noticed that it happened when I was writing files to it over SSH. My best guess is that the interference comes from I/O activity somewhere on the board.

It does seem to decrease in intensity when I’m playing a game, but I’m guessing that’s just due to decreased I/O activity. It definitely happens when the system is basically idle though (for example, I paused a game which has no audio when paused, and I could hear the chirping sounds then).

I’ll definitely open a ticket and get those photos to you as well.
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#7
(06-11-2019, 11:55 AM)GameBro Advance Wrote: It does seem to decrease in intensity when I’m playing a game, but I’m guessing that’s just due to decreased I/O activity. It definitely happens when the system is basically idle though (for example, I paused a game which has no audio when paused, and I could hear the chirping sounds then).

I’ll definitely open a ticket and get those photos to you as well.

Okay, good. We can proceed with the support ticket when we receive those.

It's pretty normal to hear that IO/SD sound while booting up. Typically, once the audio has been initialized, that sound is not noticeable. It should be inaudible in game.
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