7.1 vs 5.1 vs 2.1

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  • randommail

    Any audiophiles here?

    What happens to a Bluray discs' 7.1 soundtrack when played back on a 5.1 or 2.1 system?

    What happens to a regular stereo music CD? when played on a 7.1 or 5.1 system?

  • cashface0
  • d_rek0

    Stereo electronics will sometimes "up-mix" or "down-mix" the audio to fit your component setup. It doesn't necessarily mean you're losing / gaining any audio - just that it's compressing or forcing audio into different channels.

    Ideally you would watch a movie mixed with 7.1 on a component stereo system with 7 component speakers and 1 subwoofer, since that is the setup the audio was mixed for. If you must watch it on a 5.1 then the audio would get downmixed and two channels might now be compressed into one to compensate for hte speaker loss. The problem with this is that the audio mix is now played back in a way not intended by the audio engineer who mixed it. Vice versa for 5.1 playback on a 7.1 system, so on and so forth.

    • thanks. my biggest concern was whether you actually lost the 2 extra channels completelyrandommail
  • d_rek0

    Sometimes, and it really depends ont he make and model of your receiver, you will lose the audio channels. Older stereo equipment might not have electronics to mix the audio for you so you could potentially lose the audio channels. Newer equipment tends to mix it by default and even will have multiple settings to force different mixes for the audio.

    For example, on my Onkyo receiver, I can force 5.1 audio from a 2.1 audio source. What it does is simply replicates the stereo channels to the center and rear channels of my 5.1 setup.

    • replicates is the wrong word, but using the on-board electonics and software creates a stereo mixd_rek
    • for the rear channels and a separate mix for the center channeld_rek
  • luckyorphan0

    As d_rek said, it's all about the source.

    Most DVD movies (even blu-ray) are still not mixed with 7.1 sound, so for now, owning a 7.1 system is kind of a hope for better materials that are due to come out (much like the current 3D TV craze).

    It all depends on how big of an audiophile you are trying to be. Most untrained listeners can't hear the difference between a solid 5.1 and a 7.1 mix, even if they sit through blind testing (as we do at my company all the time). But if you're really training your ears to hear the difference, it's pretty great.

    Just make sure that in the end, when you output a 5.1 mix on your 7.1 system, you change the setting on your receiver to accommodate such a shift.