Can you please help, Pioneer VSX-921 optic and HDMI signal issue


Novice Member
hi guys

here is the video i recorded related to my problem

simply the problem is sometimes vsx-921 doesnt show the all speakers and the signal name with little letters like dts or dolby next to the speaker that normal? is there something wrong with the avr?

it just shows that the signal is digital or dolby feels like i am not real 5.1.i have to switch between inputs to make avr show the speakers correct.

although i have the sound in every situations.



Distinguished Member
Dolby Pro LOgic is a form of audio processing that is used to create pseudo surround or to extract additional channels matrixed (downmixed) into stereo audio content. It is only applicable to audio lacking the full compliment of potential surround channel, those channels being 5.1 in the case of Pro Logic and Pro Logic II or 7.1 in the case of Pro Logic IIx. If an incoming audio format consists of the full compliment of discrete channels then the corresponding Pro Logic processing is overridden because it is not required, but if the incoming audio has fewer than the full compliment of channels then Pro Logic creates pseudo channel for those that are missing. So if you input stereo audio and apply Pro Logic II to it you get pseudo 5.1, that being the stereo channels plus additional pseudo channels the Pro Logic processing created to make the audio up to 5.1. Turn off the Pro LOgic processing and you'd get just the native stereo content. If you input a discrete 5.1 format such as DTS or Dolby Digital 5.1 then Pro Logic II is overridden even if engaged because it would not be required because there is already the full compliment of channels present.

Dolby Digital and audio such as DTS are discrete formats while Pro Logic and similar modes are forms of audio processing.

What is your audio source. You may need to configure the source device to output multichannel formats via HDMI? This is generally termed Bitstreaming.

Also note that some forms of media do not deal with multichannel audio. CDs for example are primarily associated with stereo content and not discrete multichannel surround sound. You'll only get discrete 5.1 in association with content that is actually encoded with it.
Last edited:


Established Member
Pioneer AVRs will only show the signal coming in, not what you can actually hear.
If the material is say Dolby Digital 2.0 (common on some HD channels) then only L and R will light up. If you add a ProLogic II processing so sound comes out of all speakers, the Pio will still only show L and R lit up, but will show ProLogic II on the display.

So for a CD this will always be stereo coming in, and thus will always just light up L and R. If you choose to add processing, that won't change the lights ;)


Novice Member
So the point is there is already a signal which is a DTS coming from pc to avr via optical cable.But sonetimes as you see in the video the avr cant represent it.

I had to switch between inputs and come back again to the input CD to make it represent signal the way it should be like showing every available speaker icon which has to be 5.1 and the signal name with the small letters etc..


Novice Member
i start switching the signals between the signals dolby and dts over creative console launcher and it sometimes recognize the signal as stereo and i get no sound.i make it ok by switching the inputs and back to the CD input as you see in the video


The latest video from AVForums

Samsung & LG UK TV Prices 2023; Amazon Fire TV Cube; Calibration Tools of the Trade + AV news
Subscribe to our YouTube channel
Support AVForums with Patreon

Top Bottom