3.5mm Line out to Sonos Amp only playing clearly on one speaker

  • 19 November 2022
  • 11 replies

Userlevel 1

After exhaustive troubleshooting, I’ve narrowed the issue down to the 3.5mm Line Out from my Optoma UHZ50 being the culprit. 


Setup: Optoma UHZ50 Projector sending audio to Sonos Amp via 3.5mm “Audio Out”. The wire is one-sided on the UHZ50 side, then has a red and black end which plug into my Sonos Amp. My Amp powers to Definitive Tech DI-8R Ceiling Speakers. 


The issue: One of the two speakers is very low, static, and simply sounds bad. I tried troubleshooting everything - new speaker wire, different banana plugs, even swapped the speaker (I have 4 and 2 are in box) and even tried a different Sonos Amp (I have 2, one is still in box). Nothing fixed the issue, so the only thing left to try was replacing the 3.5mm cable, so I went ahead and swapped that (I also have two of those) and the issue persists, but if I flip the Red / Black the opposite speaker has the problem. Basically the “Left” speaker out on the Amp is the problem when I have the “Red input in the red plug and the black input in the black plug” but if I flip the two (red into black, black into red) then the “Right” speaker has the issue. 


Therefore, my issue is that the 3.5mm Audio Out Line from the UHZ50 is only sending clear audio to one channel on my Sonos Amp. I tried looking at the audio settings on the projector but no dice. 


Am I missing some kind of obvious issue with 3.5mm Audio Out lines into Amps that’s causing this? Could me projector be defective? Is there anything left to try on the Sonos side? 


Has anyone here had success sending Audio to their Sonos Amp via 3.5mm Audio Out? 


Thanks in advance. 


Best answer by Airgetlam 19 November 2022, 17:15

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11 replies

Userlevel 1

Update: I plugged a set of headphones into the UHZ50 and both sides work perfectly, so something is going on with either the cable, or my Amp lot receiving both channels clearly.

It could also be the cable itself. There really shouldn’t be any issue in carrying a stereo signal (not a 5.1 signal) via a 3.5 mm output to the RCA input on the Sonos. There would be that minimum of 75 ms delay, though, which would make lip sync a challenge. 

Userlevel 1

I tried two different cables, but they’re both the same brand so maybe it’s just a cheap Amazon cable being problematic. I ordered a different brand to arrive tomorrow and see if that helps. 

You’ve proven it’s not the output of the projector by using standard headphones. Have you used another device to feed the RCA inputs on the Sonos? Something like a regular CD player, or DVD player should have line level RCA outputs that you could connect and test with. 

Right now, you only have eliminated one potential out of three. 

Userlevel 1

@Airgetlam Great point. Let me see if I can find another device with a 3.5mm output. My laptop might have one….

If you can, find something with a standard RCA output, you’d want to remove that 3.5 mm cable as a potential. You’re trying to figure out if the Sonos input is the issue. 

Userlevel 1

Well I’ll be... I plugged my laptop into the Amp using the same 3.5mm → RCA cable that’s currently being used by the Projector and the audio was perfect on both sides. But if I plug headphones into that same projector jack the audio comes out on both sides… so what the heck is it???



My guess is there’s something odd about that cable, and it’s not making full and appropriate connection in the projector…but I’m not there to test and see. I would wait until you get the new cable and do further testing. And in the meantime compare the visual appearance of your headphones 3.5mm connector to that RCA splitter cable’s 3.5mm connector, too. 

Userlevel 1

Thanks… Real head-scratcher here. I’ll keep you all posted.

I have the same issue. I get sound out of both speakers when connecting to my denon receiver. However when I connect to my port only get sound from one channel. Swapped inputs and cords. Same result. However no issues when hooking up my pc to the denon receiver. So 100 percent a sonos issue they won't admit to. 

What did Sonos say, when you submitted a diagnostic, and called them?