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What is "Phase" and "Double Bass?" on the OUTLAW 950?

Discussion in 'Archived Threads 2001-2004' started by NickSP, Nov 11, 2002.

  1. NickSP

    NickSP Supporting Actor

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    I am into my 3rd week with the Outlaw and have slowly begun appreciating this unit until I read a review on AR that talked about Double Bass and phase related issues on the AR. Phase I believe must have something to do with BAss but what exactly is that and what is double bass? [​IMG]
     
  2. Lewis Besze

    Lewis Besze Producer

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    Both are referred to the external 6 ch input.
    The double bass issue is "valid" if you don't use the analog BM associated with this input by selecting "off".Even in that case the the sub output still receive a "summed" bass even though the other channels receive full range signals.This is essentially will "duplicate" the bass content that's already in the main channels in the sub/LFE channel.
    The phase "issue" is much less verified by many and [including me]and was I think brought to light by Kevin C. Brown at the Outlaw salon.
    Kevin states that the lfe channel is out of phase on the 6 ch input,compare to the one generated by the processing chip in digital domain.In other words if you use the Avia disc's phase tests presumably with the digital connection from you DVD player,and everything checks out,the analog "cousin" through the 6 ch input would show 180 degree difference[opposite polarity]compare to the mains,and the digital lfe channel.
    I certainly can't verify this claim on my 950 based on tests I conducted.
    Hope that helped.
     
  3. NickSP

    NickSP Supporting Actor

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    That certainly helped, thank you Lewis.
     
  4. David S

    David S Stunt Coordinator

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    "In other words if you use the Avia disc's phase tests presumably with the digital connection from you DVD player,and everything checks out,the analog "cousin" through the 6 ch input would show 180 degree difference[opposite polarity]compare to the mains,and the digital lfe channel".

    And would you actually hear this playing a source (ie. SACD or DVD A music), or just hear it thru a "test tone"??. If you hear it, what to correct - flip the phase on your sub??
     
  5. Kevin C Brown

    Kevin C Brown Producer

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    Lewis is close. [​IMG]
    Here's exactly how I tested and what I found:
     
  6. David S

    David S Stunt Coordinator

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    Why is it such a big deal across the boards then??
     
  7. Kevin C Brown

    Kevin C Brown Producer

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    Because it is still *wrong*. And with some material, the effect may be very apparent.

    Simple solution: change the phase on the sub when switching back and forth. That's what I do.
     
  8. Lewis Besze

    Lewis Besze Producer

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    180 deg is complete opposite,like switching polarity,and that should be very audiable.The effect is more like "lost" bass lines in some cases,but sometimes it's over powering,depends at what frequency the "cancellation" or "doubleing" occurs.
    My 950 is free of this artifact,but it is warrant further investigation by others,to see if they have this anomoly.
     
  9. Kevin C Brown

    Kevin C Brown Producer

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    Lewis- 2 others have confirmed what I observed. Have you done the test with a discrete test tone disc? I have tried the phase tests on Avia, and they certainly work between the normal speakers, but between normal speakers and the sub, I thought the Avia test didn't give me enough confidence that I had it correct. Lo and behold, when I switched to the test tone disc and plotted points, I had the phase wrong, and the sub volume adjusted too loud to compensate. Something to think about... [​IMG]
     
  10. Lewis Besze

    Lewis Besze Producer

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    Kevin,
    No i haven't tried a cd test tone,just Avia,
    however that is sufficient to me to find out about if it was completely out of phase or not.I use to moved my subs quiet a bit around in my old house,and it always required me to check the phase relations to my mains,and Avia was an adequate tool to notice such problem.However I don't have continuously variable phase knob as I have pro amps with DIY subs,that could uncover more precise problems if I have any,so I'm contemplating on the SVS "Black Box".
    Anyway as I said it the 180deg out of phase is very audible,so that much error I could detect by ear rather easily,so is most people,but I'm open to suggestion as which test CD should I get to "probe" this issue a little further.
     
  11. Kevin C Brown

    Kevin C Brown Producer

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    Lewis- One conclusion that I cannot draw:
    DD vs the analog inputs.
    I only did 2 channel LPCM digitally, vs analog 2 channel digitally processed in the 950, vs the L & R of the 5.1 analog inputs.
    It's possible that the DD feed is in phase with the analog inputs (but that would put it out of phase with digital LPCM, which isn't likely). I'd expect the DD feed to definately be in phase with digital LPCM.
    Another conclusion that I can't draw: there *are* differences between 950's. Could be another one. [​IMG]
     
  12. Lewis Besze

    Lewis Besze Producer

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