Rear Surround on Onkyo TX-SR875

[azjrf67]

I have an Onkyo TX-SR875 and have 7 speakers hooked up to it. I have a Panasonic DMP-BD55 blu-ray player hooked up to the onkyo with HDMI. On the bd55 I have the dolby formats set to "bitstream" and the secondary set to "off", also have hdmi audio set to "on". So, when I play a blu-ray, like say, Transformers, I can see on the onkyo display "Dolby TrueHD" or "Dolby D EX" which I would think would play on 7.1 setups. However, the display on the onkyo doesn't show that the rear left and rear right surround speakers are active.

If I send the white noise test tone through the Onkyo setup, the speakers do play the test tone. Also, if I play an audio source in All-Channel Stereo, the speakers will produce the music. I do have a Zone 2, but it isn't powered, I have the zone 2 speakers plugged in to a secondary amp and am using the zone 2 pre-out outputs to that amp to power those.

I can't think of what I've done wrong, but no matter what I do, I can't get those rear surrounds to work when playing a blu-ray.

Any help would be greatly appreciated. Thanks in advance for those that read and offer suggestions.

[MrBoylan]

"Transformers" is actually a Dolby TrueHD 5.1 channel release. Not all receivers can take a 5.1 channel PCM or TrueHD track and then apply additional processing to it -- e.g., Dolby ProLogic IIx -- to create a 7.1-channel mix. The Onkyo 875 was one of the first generation receivers to support Dolby TrueHD and DTS-HD MA decoding so I wouldn't be surprised if it does not have the ability to create a 7.1-channel mix (applying Dolby PLIIx) from a 5.1-channel lossless source. It would work with the lossy soundtracks (Dolby Digital, core DTS) but probably not against DTS-HD MA 5.1, Dolby TrueHD 5.1 or PCM 5.1. Do you have any Dolby TrueHD 7.1 titles, like "Megamind?" This will tell you whether your receiver is working properly with a true Dolby TrueHD 7.1 channel source.

For DTS-HD, you're actually in luck. Not only are there many true 7.1 channel mixes currently available in DTS-HD Master Audio, but the Panasonic players have an interesting feature where they will "upconvert" any DTS-HD 5.1 and 6.1 channel mixes to 7.1 channels if you set the player to its PCM output, instead of bitstream. You won't have that "DTS-HD" light lit up on your receiver if you go this route, but it will get you a 7.1 channel mix from DTS-HD MA and DTS High Resolution 5.1-channel and 6.1 channel soundtracks. Also, there is no sonic loss when you decode from DTS-HD MA to PCM in the player so you don't have to worry about making any sacrifice in sound quality if you go this route.

Hope that helps.

-Chris

[azjrf67]

It does help, thank you for responding.

I do have Toy Story 3, which is a 7.1 source and I can verify that the reciever is working properly for that source.

One thing that is confusing about my player (pany DMP-BD55), too, is that it seems to suggest that an additional cable is needed in order to get those other two channels. I have it using only HDMI: have hdmi audio "on" and on my reciver have selected hdmi as the digital source for the player and like I said, with a 7.1 source it seems to work, but not without the 7.1 source. Here's the manual (http://service.us.panasonic.com/OPER...MPBD35-MUL.PDF), the item I'm referring to is on the bottom of page 8, in the section called "Enjoying High Bit rate Audio of BD-Video" under "Necessary Connections". If this is the case, I don't know how to tell my Onkyo to use two digital inputs for the same source.

For the other suggestion, I will give it another try, because I couldn't get it to work. I have Avatar, which is the only other DTS-HD MA source I have and I set the player to be "PCM" for both the Dolby and DTS and have secondary audio "off". I will try it again, though, because I was also playing with the "extra cable" so maybe I didn't try just this configuration alone over hdmi. One other interesting thing to note about Avatar is that it seems to be the only BD that I can't get to display a 1080/24p picture through my projector (pany PT-AX200U) which is supposed to do 1080/24p over hdmi.

[MrBoylan]

Hi,

Yeah, I'm pretty familiar with the BD55 as I reviewed it and kept it as a reference for a few months after it came out. You definitely do not need a second cable to do 7.1 over HDMI as you have confirmed with the "Toy Story 3" 7.1 Disc The limitation of not being able to do 7.1 from a 5.1 lossless or PCM source is on the receiver side, not the player side. And yeah, the user manual can be a little confusing when it comes to the digital audio settings. I believe "Toy Story 3" is actually DTS-HD Master Audio 7.1 even though it was one of the first to be released in theaters in Dolby Surround 7.1. There aren't as many Dolby TrueHD 7.1 titles available as there are DTS-HD Master Audio 7.1 discs.

In terms of that DTS to PCM test, yes, you have the settings correct: Under the digital audio settings, "DTS" should be set to "PCM" and "BD Secondary Audio" should be set to "Off."

Strange that you can't get 24p output on the "Avatar" disc but really not that important. Your projector may accept a 1080p/24 source, but it converts that to the projector's native 720p/60 resolution for display anyway. So doing that scaling in the player instead of the projector should not produce very different results.

Anyway, try the Avatar disc again and see how it goes. A DTS-HD MA 5.1 or 6.1 soundtrack should definitely be upconverted to 7.1 PCM over HDMI if you use the DTS decoder built into the player. But it is key to also make sure BD Secondary Audio is set to "OFF" to prevent the player from reverting to the lossy core DTS 5.1 track.

Good luck and let us know how it goes.

Regards,

-Chris

[azjrf67]

Thank you again for the help, advice and clarification.

I think most of the problem was a lack of understanding on my part. It seems that I was focusing too much on the display on the Onkyo showing which speakers were active and not so much on what was actually coming out of the speakers on various surround modes. As it turns out, for the soundtracks that are 5.1 "native" if I keep the player on bitstream then I can't get any sound out of the rears for Dolby TrueHD or DTS Master, but if I let the Onkyo be in other modes, like Dolby D Ex, or any of the THX modes (like Ultra2) then I do get sound out of the rears, and I'm ok with how it actually sounds in experience, so I think I'm all set.

As I order more 7.1 "native" BD (just got Tron) I will have to fiddle with the receiver less.

Thanks again for all the help.