Orange PI PC analog-codec Left channel working only - how to get stereo

[Peter Gregory]

I'm on an Orange PI PC running Armbian_23.08.0-trunk_Orangepipc_bullseye_edge_6.5.1_minimal 

I've enabled analog audio out the 3.5mm jack using overlays=analog-codec in /boot/armbianEnv.txt

I'm connecting the analog 3.5mm jack to a 3watt amp & speakers.  It works mostly, but I only get audio on the left channel.

Alsa mixer Line Out only allows one channel to be unmuted at a time - left channel or right channel.

Left channel sounds pretty good (DAC reversed appears to increase dynamic output).

Right channel is very low volume and appears to be "squelched" - is the audio signal reversed from ground or something?

Anyway, is there some way to get stereo output working similar to a USB sound card with stereo DAC?

I'm currently connecting the left channel to both left/right inputs to my amp and that appears to be working well.

Any audiophiles out there get stereo working through the 3.5mm jack?

 

 

Edited September 17, 2023 by Peter Gregory

[Peter Gregory]

Turns out this issue was my audio jack.  I think the stereo plug was shorting the video out and audio channels together causing a hot mess.

I bypassed the audio jack by soldering my analog audio connections directly to the SMD pads in the audio jack and the sound is great.

Now I'm having trouble getting my PAM8403 2x 3W Mini Digital Power Amplifier Board AMP Class D and orange pi pc to work with a single power supply.

I can power the pi from a 2a 5v supply and the amp from a separate 1a 5v supply and it works great. No hum or audio problems (I thought it could be louder, but it is not bad).

If I attempt to power both devices from a single 3a (or more, I tried up to 5a) 5v supply it does not work.

It looks like I have a big ground loop problem with the audio outputs and the power amp.  I have some audio isolation transformers on order and I hope that will fix the issue.

Once the analog driver kicks on, I get a loudish "pop" from the amp and the 5v voltage dips briefly below the minimum to keep the board running.

Even with separate power supplies, I see a lot of ripple and drops from the 5v supply on the amp while playing at higher volumes.

I'm not sure if I need to add a low/high filter to keep the low / high frequencies out or if the audio isolation will do the trick.

Any advice on getting an external audio amp to work well with this board will be appreciated.

[Peter Gregory]

The answer was soldering the left/right/gnd connections directly to the SMD pads and using audio isolation transformers.  They eliminated the loud pop when the audio codec kicks in and removed the ground loop causing the amp to draw too much power.  The sound is great now.