7.1 -> 5.1 question

[someonehs]

I was wondering if someone could help me out. I have a ps3 hooked up to my denon amp, and have everything streaming PCM. I used to have 7.1 setup but had to take it down (temporarily). I was wondering if an audio track is 7.1 uncompressed, what happens if you only have a 5.1 setup? do you loose 2 tracks, or does it adjust and output via the 5 speakers? Any insight would be appreciated! thanks.

[GardenVariety]

Most 7.1 Discs have a 5.1 Option. If you leave it setup as 7.1 it will be missing two tracks (however insignificant).

[LastSonOfKrypton]

I think if you play a 7.1 track on a 5.1 setup the extra sound is added into your surrounds. There shouldn't be any loss of sound.

[aaronwt]

It would depend on what the receiver does. My last 4 receivers have been Denon but I've never used a 5.1 setup with it so I don't know how it treats the 7.1 signal. I've been running 7.1 since 2001 with my last 5 receivers.

[GardenVariety]

We're talking about 7 discrete channels. Unless your specific receiver has the ability to downconvert a 7 channel signal into 5 channels it will only recieve 5 channels.

[LastSonOfKrypton]

Originally Posted by GardenVariety

We're talking about 7 discrete channels. Unless your specific receiver has the ability to downconvert a 7 channel signal into 5 channels it will only recieve 5 channels.

Most all recievers that support 7.1 can downcovert to a 5.1 setup. I'm not sure about LPCM tracks though, should work fine for DD and DTS though.

[aaronwt]

Originally Posted by GardenVariety

We're talking about 7 discrete channels. Unless your specific receiver has the ability to downconvert a 7 channel signal into 5 channels it will only recieve 5 channels.

It's eight(7.1) discrete channels. My last 3 receivers had no problem with 8 discrete channels over HDMI but I never tried going from 8 channels to 6(5.1) since I have a 7.1 setup.

[Aurora]

When I called Denon customer service to ask them this very question, I was told that "the other two channels just have delayed effects" and that nothing is done with the other two channels. He said, "Don't worry, you're not missing info" based on the previous statement. It sounded like the other two channels are not being mixed into the other 5.1 channels.

Yes, that's what I was told. No, really.

I'm not sure I believe it, and it wouldn't be the first time Denon customer service is wrong. Well, ok, actually, it would. That call was placed before the one I just made and got wrong info, so that would make my most recent call the second time and the one about 7.1 -> 5.1 the first.


I think the only way you'll get a real answer is to do the following:
1) Turn off your rear surround speakers, and then listen to a 7.1 mix.
2) Listen to the 7.1 mix with all the speakers going.
3) Listen to a 5.1 mix of the same soundtrack.

Compare all three of those. Find a part where the SB channels have sound in them from #2. Then compare the SR/SL when you used 5.1 speakers in #1 to that. You can use #3 to get the differences between the 5.1 and 7.1 mixes. That'll help you figure out if the "delayed effects" claim I was given by Denon is right.

The best way to go about doing it is to use a 7.1 DTS-HD MA track. What you can do is get the entire 7.1 track to the receiver (PS3 decode) and then use that. Then connect the player with an optical/coax cable and the PS3 will send the 5.1 DTS core, so you can use that as the 5.1 mix. Hopefully, the lossy compression won't make the test invalid. Or I guess you can try using a DVD of one of the New Line 7.1 DTS-HD MA tracks, since it'll just have a Dolby 5.1 track on it, most likely.

You can also try 3:10 to Yuma. It has a 7.1 PCM and a 5.1 DD EX track. Unfortunately, the EX might wreck the test, but it's hard to get find the right stuff to do this.

[someonehs]

thanks for all the help everyone! Watched Rambo last night and it sounded pretty good! My current setup isn't the greatest as I had to rearrange the furniture in the room as I am selling the house. This leaves the rears more on the left side than anything. Hopefully in the new place i'll be able to get the 7.1 back up and running properly!