Crossover For Music

Discussion in 'Archived Threads 2001-2004' started by Arron H, Jul 10, 2002.

  1. Arron H

    Arron H Second Unit

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    Many on this board have suggested the following settings for bass management:

    1. Set all speakers to small.
    2. Turn the crossover on the sub fully counterclockwise (bypass mode).
    3. With speakers set to small and sub crossover bypassed, the receiver's crossover will handle the bass management for the system by sending LFE and all of the remaining low bass below the receiver's built in crossover to the sub.

    I realize that there is some debate about items 1-3, even for HT but are these the ideal crossover settings for 5.1 channel music or 2.1 channel music?

    It was recently suggested to me that setting the crossover on the sub about 10Hz higher than the flattest frequency response for the mains and running the mains on the large setting would be better for 2.1 channel music. Further, it was suggested that setting all speakers to small with the sub crossover set at same level as the receiver's crossover would be better for 5.1 channel music. The reasoning suggested was that "it would increase the order of the rolloff and make it less likely that the bass would sound like it was coming from the corner" (my sub is not quite in the corner but fairly close to a corner).

    Does anyone have any thoughts opinions about the ideal crossover settings for music?
     
  2. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    When the mains are set to large and the source is 2 channel music, and the sub is fed the "sub out" or "LFE" line level signal, then the receiver does not have a clear bass management directive. Should the "large" mains get everything and the sub nothing ? Should the signal below the crossover be send in duplicate to the mains and sub ? Somewhere in between these extremes ? Its up to the receiver maker to choose, and most I believe just kill the sub or send it next to nothing. Its a no win situation- either the sub is not used for what it does best or there is duplication of deep bass. if the receiver sent a duplicate signal (most don't) then it might be possible to set the sub's crossover at the point where the mains naturally roll off to get a flat curve. Of course, the other way to do mains large is to feed the sub speaker level signals, let the sub cross it over and send the sub amp's high pass to the mains. This is the old fashioned way that predates on-board receiver crossovers. I fail to see the advantage of using the sub's crossover rather than the receiver's, esp when the sub's crossover is potentially mangeling the signal at the speaker level.

     
  3. Greg_R

    Greg_R Screenwriter

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    Click on this link and read the post by Brian Florian (4-5 posts down). His post summarizes my feelings exactly. In short, I strongly suggest doing #1-3 on your list (for music & movies). If you can localize your subwoofer then it isn't calibrated properly or it is a poor performer.
     
  4. Arron H

    Arron H Second Unit

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  5. BruceD

    BruceD Screenwriter

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    Here's the situation I see with many receivers/processors.

    The high-pass xover in the receiver reduces the signal to the main speakers with a slope of -12dB per octave. The receiver is also expecting a corresponding -12dB slope from the natural low frequency rolloff of the main speakers (these two are suppose to Sum to a -24dB slope). Mostly, the only speakers with a natural -12dB rolloff at 80Hz are THX certified speakers.

    The low-pass xover in the receiver reduces the signal to the sub with a slope of -24dB per octave.

    In order for the receiver's xover to work correctly at the xover frequency for a smooth transition, the high-pass and low-pass need to sum to zero.

    This doesn't occur about 98% of the time, because most main speakers don't have the required natural -12dB low frequency rolloff.

    The only way I've found to get a really smooth mix between mains and sub is to measure and use a parametric EQ with an external -24dB electronic xover (low-pass and high-pass sum to zero) between my mains and sub.

    This way I get the benefit of the sub for music as well. This means I say sub=NO in my HT speaker setup, and I can set the xover frequency anywhere I want.

    I do this even though my mains are rated -3dB to 32Hz.
     
  6. John Royster

    John Royster Screenwriter

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    or just don't use a sub for music? simple, don't have to worry about anything else.
     

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