what does the crossover in the receiver do

Discussion in 'Archived Threads 2001-2004' started by gene avallon, Jan 11, 2002.

  1. gene avallon

    gene avallon Stunt Coordinator

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    with all speakers set to small,what does the crossover in the receiver do?does it affect the lfe channel? does it affect anything when the receiver is in the 5.1 mode when watching a dvd or hdtv in the 5.1 mode.does it do anything when the receiver is in dolby digital,or dolby soround? the crossover is 80,100,120.does it affect anything in just stero,like watching tv?I never never listen to music cds.
    the manual tells me nothing.oh when you set speakers to small where is the cut out at,what frequency.
    I know this is a lot ask,but if I can use the shift key you should be able to help a little.
    gene
    GOD BLESS AMERICA[​IMG] [​IMG]
     
  2. PatrickM

    PatrickM Screenwriter

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    When you use bass management within a receiver by setting your speakers to small the crossover frequency is the frequency at which the bass management splits the signal.

    So, if you set your crossover frequency to 80Hz and set all your speakers to small and you have your subwoofer hooked to your LFE then all frequencies that are above 80Hz will go to your five surround speakers. Anything that was supposed to go to any of those 5 speakers that is below 80Hz now goes to the subwoofer along with any dedicated .1 LFE information.

    This bass management usually only applies to the surround modes but it varies by receiver. Also remember that the split is not a brick wall at 80Hz. The filters do have some slope to it so some frequencies below 80Hz will still come through but at reduced levels.

    Patrick
     
  3. ColinM

    ColinM Cinematographer

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    The crossover is (usually) active only when listening in a way that allows the fronts to be set to small.

    For instance, my cd player has no digital out, only l/r rca's, and I have to listen to it with the fronts 'large'.

    The crossover in your sys can be set at 80, 100, and 120.

    Affect the LFE? Not sure. I know the x-over will keep bass away from your fronts at those freq's and below, but LFE is dedicated to the sub, from 3-120 HZ. I really not sure about the x-over and LFE working together.

    Lotsa questions...I'm sure I missed something....ask away!

    - CM
     
  4. gene avallon

    gene avallon Stunt Coordinator

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    when im watching tv in stero the two mains are real boomie so I should set the crossover to 120.if I dont have the speakers set to small the crossover wont work right? I intend to run all the speakers to small with the 2 new subs.I dont complety understand yet but getting there.
    thanks
    gene[​IMG]
     
  5. Doug_L

    Doug_L Stunt Coordinator

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    I'll try and answer as many questions as I can, but it would help if we knew what your equipment is.

    - Crossover will direct signals above a certain level (80Hz and 100Hz are two most common, but there are others) to the proper channel (front left, etc) and below the crossover point to the subwoofer.

    - Crossover will not have any effect on LFE signal, as that signal is ALWAYS directed to the subwoofer, regardless of speaker setting (small/large). Note that when speakers are set to small the subwoofer will produce both the LFE signal AND any signal below the crossover point.

    - The crossover should (and I say should because not all receivers/preamps do this the same way) work the same with any stereo signal, as well as one encoded in Dolby Surround (digital or analog). Some receivers allow a stereo signal to bypass the crossover, but I doubt that's an issue with you as you "never never" listen to music. You may have to set your speakers to small/large for each input device, though.

    - I can't tell you the crossover point without knowing your equipment, although if your reciever/preamp is THX Certified, then it's 80hz. Note as PatrickM said, this is not a brick wall, and some of the signal above and below the crossover point will go to the "wrong" destination.
     
  6. gene avallon

    gene avallon Stunt Coordinator

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    just working with a little ole jvc receiver rx 884bk,if the thing had pre amp out id have a seprate amp,so this is fine for now.Ijust want to understand it as much as possible.
    thanks
    gene[​IMG]
     
  7. Ted Lee

    Ted Lee Lead Actor

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    the cross-over point isn't a brick-wall, correct?

    in other words, the frequency is actually crossed-over a little above/below 80Hz?

    just wondering...
     
  8. PatrickM

    PatrickM Screenwriter

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    If we're talking about a 80Hz crossover frequency then 80Hz is defined as the -3dB point or where the signal is -3dB lower than the pass band which is the frequencies higher than 80Hz if we're talking about what is going to the 5 surround speakers.

    I have heard that the typical slope of a digital crossover is in the neighbourhood of 20dB per Octave I believe so that means if 80Hz is -3dB then half of 80Hz is 40Hz, which is an octave lower, then 40Hz would be -23dB lower than the pass band. An octave lower than 40Hz is 20Hz and it would be an additional 20dB lower at -43dB in this example.

    Patrick
     
  9. gene avallon

    gene avallon Stunt Coordinator

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    WHAT YOU GOTTA BE KIDDEN
    GENE[​IMG]
     
  10. PatrickM

    PatrickM Screenwriter

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  11. gene avallon

    gene avallon Stunt Coordinator

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    people in canada are pretty smart
    gene[​IMG]
     
  12. PatrickM

    PatrickM Screenwriter

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    So Gene, is your lack of capitals a silent tribute to E.E.Cummings?
     
  13. ColinM

    ColinM Cinematographer

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    Aw, cripes...
    Hey, why do all youse Canucks say OOT insteda OUT?
    Over an' OOT
    KIDDING!!!!!!!![​IMG]
     
  14. gene avallon

    gene avallon Stunt Coordinator

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    patrick
    no lack of school learning,and not learning about the shift key till lately. CANADA sorry. my mother came here from SAINT JOHNS a long long time ago.
    GOD BLESS AMERICA
    GENE
    [​IMG]
     
  15. BruceD

    BruceD Screenwriter

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    Gene,
    Let's assume a receiver bass crossover of 80Hz.
    Picture this in your mind, we are viewing two snow-capped hills from the side and far away. These two hills have two ski slopes that appear to intersect or crash into each other:
    Now let's define one hill as the main speaker and everything as high as the hill to be high-pass sound.
    The other hill is the sub and everything as high as that hill to be low-pass sound.
    The two ski slopes are the "crossover".
    Now these two slopes aren't the same, one is steeper than the other (specifically the ski-slope associated with the sub is steeper).
    What happens to sound when it gets processed by your receiver's crossover?
    SUB typically referred to as the low-pass side of the crossover
    As the output frequency of the sub rises and approaches 80Hz, the SPL output of the sub gradually goes down above 80Hz (like a skier going down the slope). How fast the SPL decreases above 80Hz depends on how steep the slope is. In most receivers this will be a 24dB/octave slope.
    This means at 160Hz (which is one octave above 80Hz) the sound level (SPL) will be 24dB quieter (lower). That is significantly quieter, meaning you probably won't hear it at all.
    definition: octave=doubling of frequency
    MAIN SPKR typically referred to as the high-pass side of the crossover
    As the output frequency of the main spkr falls and approaches 80Hz, the SPL output of the main spkr gradually goes down below 80Hz (like a skier going down the slope). How fast the SPL decreases below 80Hz depends on how steep the slope is. In most receivers this will be a 12dB/octave slope.
    Not as steep as the one used for the sub. The assumption is that a speaker already has a 12dB slope built-in to it's low frequency output. In other words, a main spkr will naturally decrease SPL as the frequency goes lower. Receiver manufacturers assume a 12dB slope, added to their receiver's 12dB slope = 24dB slope total.
    This means at 40Hz (which is one octave below 80Hz) the sound level (SPL) will be 24dB quieter (lower). That is significantly quieter, meaning you probably won't hear it at all.
    -------------------------------------------------
    The whole point of this visual is to give you a feel for the gradual slope of crossover effect. Crossovers are not cliffs with abrupt changes.
    This is typically one reason why it's hard to match subs and main speakers. Because the main speakers and sub have different frequency response curves, the output levels from both sub and main speakers through the gradual crossovers sometimes causes too much (or too little) output at specific frequencies.
    By the way, my family history (grandmother's family) goes back to Prince Edward Island.
     
  16. gene avallon

    gene avallon Stunt Coordinator

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    bruce

    thank you that an---worked my brain is filling up,doest take much.

    thanks

    gene

    cant spell that word
     

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