2. home-theater
  3. 191651-5491

Lack of Surround Sound Signal from TV to Processor... Why?

OK, I am not the "sharpest tool in the shed" when it comes to all this "new & improved" Dolby stuff but I have successfully operated a Dolby Digital 5.1 system for many years.  Yeah, go ahead and say it!  I'm old...  :)

Here is my dilemma along with the associated equipment.  I cannot seem to get any Dolby signal whatsoever from the TV to the surround processor.  Just 2.0.  I am using an LG OLED TV Model  OLED65CXPUA.  The TV tuner is an ATSC 3.0 which is (supposedly) capable of reproducing surround sound from OTA DTV signals.  The picture is wonderful and the sound crystal clear but no surround even though my research tells me there should be some surround material from the OTA signals.

I also use internet based material such as Sling, YouTube, Amazon Prime Video, FUBO, etc.  Same issue.  Everything is 2.0.  There are also hundreds of LG Channels!  Great stuff but same issue...

No matter the source, I cannot seem to get any surround sound input to the processor.  I am using the TOSlink connection which is supposedly capable of transmitting surround material of up to 7.1.  I am also reading that the new DOLBY ATMOS system is backward compatible meaning 5.1 should still work as advertised.

I have also tried using a Blue Tooth connection from the TV.  Sound is wonderful but again, no surround...

If I play a movie on the DVD player everything is normal obviously because the sound signal is produced by the player, not the TV...  

What am I missing here?  It is probably so simple I can't see it...  Any ideas?  

Any suggestions or ideas would be more than appreciated!  Thank you in advance.

Paul

tahoe36c
freediver
1,171 posts
 

The most likely candidate would be:
The Sound Output of the tv is simply not set to output a Digital signal..
https://youtu.be/HUAVERW3WMM?si=8TOg4aapSlRgzr-f............
Or:The surround processor audio settings are set to PMC 2.0 & not Digital...Hope this helps..

tahoe36c OP
10 posts
 

freediver,

Thank you very much for your response.  My TV sound menu is slightly different than what is in the video (I think it is a newer version) but I understand the options.  I have tried selecting both of the the optical (TOS link) options with the same results (otherwise there would be no sound at all...).  One is simply the optical output alone and the other allows you to keep the TV speakers active as well.  I have no idea why anyone would want to do this (I could mute the TV speaker if it worked) but I tried them both. 

The processor has indicator lights to show the incoming signal; Dolby Digital, DTS and PCM.  Optical cables are supposed to support Dolby Digital, DTS and PCM so I think everything is OK when considering the processor.  The processor is showing the signal coming from the TV as a PCM (pulse Code Modulation) signal.  The TV just doesn't seem to output any Dolby Digital signals (5.1) no matter the source material for the TV.  Every setting I try with the TV results in a PCM signal. 

The surround processor manual tells me that PCM 44.1Khz supports both 5.1 and Pro Logic.  On the other hand the chart shows that PCM 96 Khz supports neither.  I figure the signal must be 44.1Khz (there is no indication) because Pro Logic works..

Maybe I need to contact LG tech support....  

Any other ideas?

By the way, the processor is an oldie but a goodie.  It is a California Audio Labs CL-2500 SSP.  I also have the matching amplifier, the CL-2500 MCA.  The MCA was (and might still be) the most powerful 5 channel amp on the planet with all five channels capable of 500 watts.  The main speakers are B&W 801 Nautilus (with a matching Nautilus center channel and a pair of B&W rear speakers) and twin Velodyne DD-15 subwoofers.  It is very annoying not being able to drive the system in 5.1.  Very annoying to say the least!  :(

I definitely appreciate your knowledge and thoughts about this situation!

sls883
303 posts
 

Have you tried a different optical cable? Probably not it, but worth checking. 

I'm wondering if the newer Dolby Digital format is not recognized by your processor.... maybe someone smarter than me will chime in. 

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