Fix your Pinebook Pro speaker connection
#1
The speakers in (at least some) Pinebook Pro are out-of-phase.  If your audio level seems low, this is probably the cause.  I just corrected this on mine, and I strongly encourage everyone to do this.  Don't wait for a software band-aid for this hardware problem; that is bad practice.

Of course, you need to remove the bottom of the PBP, and follow all the precautions that normally go with that.  Next it's a matter of unplugging the speaker connection from the mainboard.  Note the order the wires on the plug are in.  Then, mercilessly tear the red and white wires out of the plug.  Pull them out by lifting them from the plug, not by pulling in the direction the plug inserts.  Swap the positions of the red and white wires, and press them back into the connector with a small flat blade screwdriver.  Plug the connector back in. reassemble the PBP, and enjoy better audio.
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#2
(11-20-2020, 08:18 PM)KC9UDX Wrote: The speakers in (at least some) Pinebook Pro are out-of-phase.  If your audio level seems low, this is probably the cause.  I just corrected this on mine, and I strongly encourage everyone to do this.  Don't wait for a software band-aid for this hardware problem; that is bad practice.

Of course, you need to remove the bottom of the PBP, and follow all the precautions that normally go with that.  Next it's a matter of unplugging the speaker connection from the mainboard.  Note the order the wires on the plug are in.  Then, mercilessly tear the red and white wires out of the plug.  Pull them out by lifting them from the plug, not by pulling in the direction the plug inserts.  Swap the positions of the red and white wires, and press them back into the connector with a small flat blade screwdriver.  Plug the connector back in. reassemble the PBP, and enjoy better audio.

I will ask hardware engineer to recheck Pinebook Pro speaker wiring. I assume you means reverse polarity affected both speaker.
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#3
(11-22-2020, 01:05 AM)tllim Wrote:
(11-20-2020, 08:18 PM)KC9UDX Wrote: The speakers in (at least some) Pinebook Pro are out-of-phase.  If your audio level seems low, this is probably the cause.  I just corrected this on mine, and I strongly encourage everyone to do this.  Don't wait for a software band-aid for this hardware problem; that is bad practice.

Of course, you need to remove the bottom of the PBP, and follow all the precautions that normally go with that.  Next it's a matter of unplugging the speaker connection from the mainboard.  Note the order the wires on the plug are in.  Then, mercilessly tear the red and white wires out of the plug.  Pull them out by lifting them from the plug, not by pulling in the direction the plug inserts.  Swap the positions of the red and white wires, and press them back into the connector with a small flat blade screwdriver.  Plug the connector back in. reassemble the PBP, and enjoy better audio.

I will ask hardware engineer to recheck Pinebook Pro speaker wiring. I assume you means reverse polarity affected both speaker.
If both speakers are connected in reverse there is no issue. What's important is the difference between the two, so if only one of them is connected in reverse the audio will be out of phase.
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#4
Is there an easy way to detect wether the speakers are out-of-phase without opening the Pinebook and "just trying and seeing what happens"?

Is there any information on which batches have this issue @tllim ?

Thank you for bringing this to attention @KC9UDX !
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#5
I would say, no. On larger speakers, you can usually tell by covering one. I have been unable to do that with these. I assume it's because of their size and frequency response, but it could be that my hearing isn't up to par right now. (It happens; I have chronic sinus issues.). But the before-after comparison, just by "feel" is striking.

I can tell you that I have two PBPs from different batches, and both had this issue. One was ordered sometime around April, and the other in the next batch. The earlier one had speaker wire pairs both red/black. The later one had red/black and red/white.

I learnt about this before I ever tried using my PBPs for audio, from another poster here. Unfortunately I don't recall who or where it was.
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#6
Any chance you could post an image of the correct wiring? I have the older version with red and black wiring.
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#7
I don't recall what the order of colours on the plug was before and after. But it doesn't really matter, at least not from my perspective, because I don't know if the speakers are colour-coded wrong or if the PBP is built wrong. There are only two ways to know when you have it correct:
1) an increase in audio volume when it's the right way
2) examine the schematics, make sure the PBP matches the schematics, and verify that the speakers have the correct colour-coding.

Maybe someone else knows if the PBP is incorrect, or if the speakers are incorrect.
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#8
Most speakers have a red dot or something, but just look at the wire color going to say the left terminal on one and compare it to the other one. The speakers are the same. It's mentioned in the wiki. Also that you can work around the problem by switching the phase in alsamixer. Usually when speakers are in phase there's more bass but these don't have much bass anyway. I do notice some sounds (like mono) appear centered between them when they're right.
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#9
While having the back cover of my first-batch ISO PineBook Pro removed, I also wanted to check the speaker connector and possibly correct the wiring.  I can confirm that the order of the wires in the connector is messed up, at least in my particular PineBook Pro.  This is also visible in the attached pictures, which all show the original, unmodified state of the speaker connector wiring.  The correct wiring is visible on page 17 of the PineBook Pro schematic.

I do wholeheartedly agree with @KC9UDX that fixing such a wiring mistake in software is bad practice.  It's really bad practice.  However, the speaker wires and the connector are so tiny and delicate that I gave up on trying to pull the wires out of the connector.  I couldn't see (almost quite literally Smile) how the wires could be pulled out of the connector without basically destroying the pins inside the connector, or destroying the wires itself.

As a note, I've been recently working on a Linux kernel patch that eliminates the crackling and popping noises, and I've expanded that patch to implement the switching between the speakers and the headphones, eliminating the need to (ab)use the acpid and to have a userspace helper script that performs the switching.  I'll also try to incorporate "normal", "l-invert", "r-invert" and "l+r-invert" as the settings available through my kernel patch, which should be usable beyond the PineBook Pro, because messing up the polarity of audio channels seems to be a rather common mistake.


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#10
(07-07-2021, 11:57 PM)dsimic Wrote: While having the back cover of my first-batch ISO PineBook Pro removed, I also wanted to check the speaker connector and possibly correct the wiring.  I can confirm that the order of the wires in the connector is messed up, at least in my particular PineBook Pro.  This is also visible in the attached pictures, which all show the original, unmodified state of the speaker connector wiring.  The correct wiring is visible on page 17 of the PineBook Pro schematic.

I do wholeheartedly agree with @KC9UDX that fixing such a wiring mistake in software is bad practice.  It's really bad practice.  However, the speaker wires and the connector are so tiny and delicate that I gave up on trying to pull the wires out of the connector.  I couldn't see (almost quite literally Smile) how the wires could be pulled out of the connector without basically destroying the pins inside the connector, or destroying the wires itself.

As a note, I've been recently working on a Linux kernel patch that eliminates the crackling and popping noises, and I've expanded that patch to implement the switching between the speakers and the headphones, eliminating the need to (ab)use the acpid and to have a userspace helper script that performs the switching.  I'll also try to incorporate "normal", "l-invert", "r-invert" and "l+r-invert" as the settings available through my kernel patch, which should be usable beyond the PineBook Pro, because messing up the polarity of audio channels seems to be a rather common mistake.

Well if you have a soldering iron you can always cut the wires and reconnect them black<->red. Put some heatshrink tube over it and that should work. It's not a "good" solution but certainly easier than rewiring the connector.
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