With mains set to small, I have a question.....

Discussion in 'Archived Threads 2001-2004' started by JohnMW, Jul 21, 2002.

  1. JohnMW

    JohnMW Second Unit

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    I get bass comming from the Klipsch RF3-II mains, RC 3-II center, and what appears to be comming from the RS3-II surrounds during the AVIA subwoofer setup test. If you are familiar with AVIA sub setup test tones, during the first level tests, it will test a main, then the sub. Is it normal to get bass from the mains and the sub at the same time with your mains set to small?
    *********** I did a search and found the answer [​IMG]
    AVIA intentionally carries its low bass test signals on each of the five main channels independently instead of the LFE channel for the express purpose of making main channel bass reproduction more accurate. Understanding why this is important means knowing the difference between three different concepts.
     
  2. Mark Tranchant

    Mark Tranchant Stunt Coordinator

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    That's actually not the answer. The whole idea of the SMALL setting for the speakers is that the processor redirects the lowest frequencies of the 5 main channels to the sub in addition to the .1 LFE channel which is always routed to the sub (if you have a sub, otherwise it ends up on the front speakers: this is why no sub forces LARGE mains).

    The real answer is that the processor's crossover is not a brick wall with =100Hz sent to the mains. Instead, the response falls away gradually with a specific slope, perhaps 18dB/octave, with the sub gradually taking over from the mains. The roll-off slope of the mains and the roll-on slope of the sub should combine to give a flat response as the sub gradually takes over from the mains. This means that at 50Hz the mains will still be producing an audible signal.

    That is why it is important for the mains to handle fairly low frequencies, and why sat/sub systems with tiny satellites are flawed. The crossover point should be no higher than about 100Hz, or you'll be able to localize the low notes to the sub. This is bad for imaging: the sub should "disappear", with the bass appearing to come from the main speakers. So even with the steepest crossovers (usually around 24 dB/octave), the mains should be able to reach about 70Hz for best integration.
     

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