Home Theater Forum › Home Theater Forum › Home Theater Hardware › Standard-Def Source Hardware (DVD, LD, CD, etc) › how is the stereo audio output created from multi-channel?
New Posts  All Forums:Forum Nav:

how is the stereo audio output created from multi-channel?

post #1 of 7
2/22/09 at 8:09am
Thread Starter 
For a system that will primarily be used for stereo music sources, I am considering getting a two-channel receiver and two speakers. The TV will be used very occasionally, and then mostly for news. It will be used very rarely for movies.

I see that HD cable boxes and DVD and Blu-Ray players have analog stereo audio outputs. How are these created? Are they carried separately from the source or do the cable boxes and disc players create them from the seven channel source? Would all the audio be present but just mixed down into two channels?

Thanks very much for your help. I realize this is a very non-standard set-up but it should be the best thing for this particular application.
Reply
post #2 of 7
2/22/09 at 2:49pm

Re: how is the stereo audio output created from multi-channel?

How the downmix is done will vary with the equipment and settings, and you really won't know how it is being done or if it is done properly. What I would do is get a surround receiver, turn off all the channels you aren't using (center, surrounds) use digital audio inputs and let the receiver do the downmix. They generally do a better job.

If you watch much video at all, it's a good idea to go ahead and get a center channel speaker for those sources.
Reply
post #3 of 7
2/22/09 at 4:08pm

Re: how is the stereo audio output created from multi-channel?

Scott: I don't know about the other multichannel sources, but with dvds the one thing you WILL notice about a surround-to-stereo downmix is that with movies that feature intense/very low frequency effects, they will be missing. That's because the standards for dvd downmixing require that the LFE (.1) channel be omitted since a source where a stereo signal is required - usually a TV - cannot handle such a signal i.e. a TV's typically low-quality and/or small speakers will be overloaded at most volume settings, producing audible distortion & possibly burning them out. I've seen this standard in action with my own stereo HT+music system.

The one option I haven't tried yet is to use my dvd-audio player which has built-in Dolby and DTS decoders, set all the channels to large and most importantly, the subwoofer channel to "no". Because if it behaves like the typical multichannel A/V receiver, it will generate a stereo downmix that includes the LFE channel. FYI: those LFE signals can be intense! I ran my surround system for years with no sub and with certain movies for example Attack Of The Clones, at barely-loud volume levels* my front mains' 8" woofers would start hitting their internal stops with a very audible "clunking" sound.

Other than this issue, I've enjoyed using my stereo system for watching movies.


* about 10:00 on the volume knob scale - my receiver uses a conventional analog knob to control a digital level system (7:00 is minimum, 5:00 is maximum)
Reply
post #4 of 7
2/22/09 at 4:42pm
Thread Starter 

Re: how is the stereo audio output created from multi-channel?

Thanks for your thoughts. This system really will be used primarily for stereo-source music and I do not prefer how that sounds through multi-channel systems. Further, for the same money I can buy a receiver with two channels of very good amplification or one with seven channels of mediocre amplification, five of which will never be used.

When the system is used with the TV, it will be either the PBS Newshour or some BBC-style movie, neither of which have much audio dynamic range.

Any further insights would be much appreciated. Thanks again.
Reply
post #5 of 7
2/23/09 at 2:34pm

Re: how is the stereo audio output created from multi-channel?

Until I purchased a surround system last month I used a stereo only primary music system with my TV's which consisted of 40 year old Bose 901 Series II and a equally old Sansui 9090DB receiver. The TV was connected to the cable with standard 75 Ohm coax and I connected the TV to the Sansui with simple RCA connections. I have been doing this for years.

When I upgraded my TV to a 52" Sony I used the same Stereo only connection method for a month and it produced even better TV sound than my old 27" GE. Naturally this TV arrangement had no effect on my stereo music listening as I used CD player, tape deck, or phono for that music. So I don't really see where your problem is?
Reply
post #6 of 7
2/24/09 at 7:14pm
Thread Starter 

Re: how is the stereo audio output created from multi-channel?

I didn't say there was a problem, I'm just asking for someone to explain the downmixing algorithms from multichannel to stereo. Thanks.
Reply
post #7 of 7
2/25/09 at 5:58pm

Re: how is the stereo audio output created from multi-channel?

My Toshiba universal player mixes everything for stereo based on the speaker setting that I input. But maybe those were only for SACD and DVD-A. The algorithms you mention may be from Dolby, or they may be from each individual manufacturer. Who knows?
You're allowed to get really anal and listen to the same DVDs over a multi-channel setup then over your stereo system and see if there's anything from the center or rears that you're missing. Or...you could do as I do with my stereo setup. Put in the movie and enjoy it on the big, big, big 13 inch screen (there's another real 5.1 100 in. screen setup inhouse).

Sorry I couldn't be of more help. I just don't sweat the small stuff, I guess.
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Home Theater Forum › Home Theater Forum › Home Theater Hardware › Standard-Def Source Hardware (DVD, LD, CD, etc) › how is the stereo audio output created from multi-channel?