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How do I stop my receiver from down-mixing 5.1 audio to stereo?

by Dawson

I have an Onkyo Sr-500 and a Samsung UN55C8000 (Old receiver + new TV). When I watch over-the-air broadcast stations, many of them are broadcast in 5.1.

I am running a digital optical cable from my TV audio out directly to my receiver. I know the cable should be able to transmit the 5.1 signal, but my receiver displays the Dolby Digital icon in addition to a stereo icon.

I can hear sound only coming out of the Front L & R speakers. I know the other speakers are hooked up properly. The only other audio selections I can make are Pro-Logic movie/games, etc. and sometimes All Channel Stereo. I have read of people having issues with their receiver down-mixing the audio signal to stereo. How do I get mine to play dolby digital 5.1?

Thanks for your help!



Hi

My first thoughts are that you haven't set up the receiver correctly.

You can test this by selecting Pro-Logic II processing on the receiver. This will play audio (including stereo) around your 5.1 speakers. Do you hear audio from all speakers when you send it some audio from the TV? If you still only hear stereo, then you haven't set the receiver correctly.

On page 18 of the Onkyo TX-SR500 manual, it tells you how to configure the unit for the number of speakers you have. Check the 'speaker adjust' setting and make sure it isn't set to 'Speaker 2ch'. It should be on 'Speaker 5ch' to play surround audio.

Do you have any other devices connected to the receiver - like DVD or Blu-ray? Do these play in surround sound?

If it is set correctly, then I can only assume you are only getting Dolby Digital 2.0 from the broadcast TV station and not 5.1. Are you absolutely sure they transmit in 5.1 over the air?

Hope that helps.

Paul (Site Editor)

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TV/Receiver/Blu-ray Player Settings
by: Dawson

Thanks for the quick response! I tested the Pro-Logic II sound and it seemed to only be coming out of the center speaker, but that might've been because it was Pro-Logic Movie. When I switch it to Pro-Logic Music, it comes out of the Front L&R speakers. When I set it to All Ch St, it plays sound out of all the speakers.

I checked the Speaker Adjust button and it does say Speaker 5ch. However, when I press Display, it changes from the Volume level to Dolby 2.0 when watching TV and Dolby 3/2.1 when watching a movie on my DVD player.

I have a Samsung BD-6900 Blu-ray player. It is hooked into the TV with an HDMI cable and to the receiver with a digital optical cable. I cannot get it to play Dolby Digital without being in stereo mode either. The receiver displays the DD icon but displays stereo, too. I know that when I watch a Blu-Ray DVD (most of what I watch are not blu-ray) it is probably encoded in Dolby Digital TrueHD, which can't be read by an optical cable, so it should be downsampling it to PCM. My receiver displays that icon, but also displays stereo! However, when I watch a non-blu-ray DVD that is DD 5.1, it still says PCM stereo.

When I watch broadcast TV shows, I see a banner come up on the TV screen that says "broadcast in 5.1" or something like that. I tried resetting by Receiver and starting from scratch, but it still plays things in stereo.

In the TV audio settings, I made sure that SPDIF out is set to Dolby Digital.

On the BD-6900, I have the audio set to PCM, and bitstream (re-code). I didn't know if I needed to turn downsampling to PCM on or off. Not sure if my receiver is 96kHz-compatible.

Thanks again!

Sound Problem
by: Paul (Site Editor)

Hi

It sounds as if your receiver is either not configured properly or it is faulty.

I would forget about the broadcast TV issue for the moment and try and get it working with the Samsung Blu-ray. You know for certain which audio format is coming from the Blu-ray - and it sounds as if the receiver isn't working correctly with this either at the moment. If you get surround sound working properly with this, then it should work correctly with the TV signal.

A couple of thoughts:

1. If you select Pro-Logic Movie, you should hear audio from all the speakers - not just the centre. However the centre and front left/right will have most of the audio. If you only get audio from the centre, then I would think there is a problem with the receiver.

2. If you are using the Bitstream Re-encode on the Samsung, it re-encodes a 5.1 soundtrack to DTS. Most modern receivers will automatically switch to this when it is received. The manual for your Onkyo suggests you have to manually select DTS for it to decode this. Therefore make sure you select DTS when playing DVD/Blu-ray. If the receiver can't decode the audio you are sending it, your hardware will probably just default to stereo audio.

3. If you select PCM as the output format for the Samsung, you will only get 2-channel stereo over optical. Check page 36 of the manual for the BD-C6900.

Once you get the receiver working properly with the Samsung Blu-ray, then you can worry about the issue with the TV signal.

Hope that helps.

Paul

Still not working
by: Dawson Hull

Well I have tested about everything I can think of! I still cannot get my receiver to play 5.1 audio from over-the-air HD programs.

I did get the DTS working on the blu ray player. That was very helpful - thanks! So I know surround sound is working on the receiver - just not when the signal is coming from my TV. The TV itself even recognizes that the program is being presented in Dolby Digital when I press the info button on the remote.

The SPDIF output is set to Dolby Digital, not PCM, on the TV. So I know that's not the issue. It's a brand new optical cable. I even tried using the other optical input on the receiver (which I know is working because it works with the blu ray player).

The receiver just continues to show Dolby Digital Pro Logic Music/movie or stereo or direct.

I'm just at a loss! Any other suggestions?

No 5.1 Audio
by: Paul (Site Editor)

Hi

Ok, so at least we've narrowed down the problem to the TV signal and we know that your AV receiver is working as it should.

When you say your TV tells you it is receiving Dolby Digital, does it actually say 5.1 or 'surround sound' too?

Are you aware that 'Dolby Digital' is a term that can also mean 2.0 (or stereo) audio? Many people think Dolby Digital means 'surround sound', but it doesn't have to be.

It may well be that you are receiving stereo Dolby Digital.

You might find this article on the different surround sound formats useful - or not!

Hope that helps.

Paul

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