It sounds like you've got Secondary Audio switched on. Turn it off.
Originally Posted by Tom Koegel
Apologies for what is probably a dumb question. I've got a sick Denon AVR 4806ci that needs to go back to the service center, and I'm trying to resurrect an ancient, non-HDMI Denon AVR 5600 to pinch-hit during the repair. The 5600 has coaxial and optical audio inputs. I cannot, however, get the coaxial input to take a bitstream from Blu-Ray. Only way to get sound, it appears, is to set the Oppo to output in the LPCM format. I understand the notion that if the Blu-Ray has a format incompatible with the 5600 (such as DTS) that it just wouldn't work. But is there something related to bitstream of conventional Dolby Digital 5.1 that would make it not work on an older device? I presume this is some sort of Blu-Ray format issue, that the bitstream it outputs is not compatible. Thanks in advance for your thoughts.
Look at page 65 of your 93's manual. That contains a grid showing what's output when Secondary Audio is turned on or off.
When Secondary Audio is turned off, bitstream puts out the native format of the disk over HDMI, but over coax or optical it sends the DVD-era version of the native format:
"Dolby Digital" if the disk is any generation of Dolby: Dolby Digital, Dolby Digital Plus, or Dolby TrueHD,
"DTS" if the disk is putting out any generation of DTS, up through DTS HD Master Audio.
Stereo PCM if the disk is encoded in up to 7.1 channels of LPCM
But when Secondary Audio is turned on, bitstream puts out DVD-era DTS even if the disk is encoded with Dolby or LPCM
(because DTS was the best DVD-era codec - it had about three times the bit rate of Dolby). I guess Oppo just didn't expect that anyone would connect the 93 to an AVR so old that it didn't speak DTS.
Since your AVR doesn't speak DTS, if you've got Secondary Audio turned on, that's why you have to use stereo LPCM to hear anything - even from non-DTS disks, since Secondary Audio sends all bitstreams as DTS.
So in Setup, go to Audio Format Setup (the third line) and on the top line of that submenu, turn off Secondary Audio.
That will let you bitstream all generations of Dolby soundtracks as DVD-era Dolby Digital in up to 5.1
and will bitstream LPCM as stereo.
On disks that have only
DTS soundtracks - common among Blu-rays but rare among DVDs - you'll still have to switch the Oppo from bitstream to LPCM and listen in stereo, since your AVR can't understand the DTS the 93 would send it.
The bigger problem is that - unlike HDMI and multichannel analog - coax and optical can't carry full quality 5.1 audio, only lossy DVD-era encodings.
For full quality, coax and optical are limited to stereo. (That's why many concert DVDs included stereo PCM tracks along with the lossy surround tracks - the stereo tracks were lossless.)
So the better solution, if you have half a dozen RCA cables, is to connect the 93's multichannel analog output to the AVR's "Multichannel Audio" jacks. That'll give you 5.1 from all disks - DTS, Dolby, and LPCM - in the full quality of the lossless surround tracks (Dolby TrueHD, DTS Master Audio, and LPCM) available on Blu-rays.
That's how I ran for many years until I got an HDMI-equipped Yamaha a year and a half ago. With most AVRs, multichannel analog requires manual channel balancing and distance tweaking (and downmixing of 7.1 to 5.1) inside the 93 (all found under Audio Processing/Speaker Configuration in setup - see page 68-72 in your 93's manual), and that input bypasses most AVRs' automatic room correction as well, but the 93's analog output is excellent nonetheless - and you avoid the knocking back of the sound quality from lossless to lossy that using DVD-era encodings like Dolby Digital and DTS entailed.