Crossover...what the heck is going on here!

Discussion in 'Archived Threads 2001-2004' started by Ryan Peddle, Oct 23, 2001.

  1. Ryan Peddle

    Ryan Peddle Second Unit

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    Ok...I have a little steam to blow off here and I'd like to blow it off here on HTF. From what I know Yamaha receivers have a built in (set/non adjustable) crossover between speakers and sub at 90hz. So as the crossover story goes, when all speakers are set to small, any frequency/information below 90 hz is sent to the sub. Not hard to understand, is it?.
    If that is the case then answer me this. I took out my AVIA ( for those who don't know what it is, do a search) and calibrated my system. I decided to do the 200-20 HZ sweep to see if my recent room adjustments had ridden me of some of the humps (it worked somewhat). Then I decided to do an experiment. I disconnected the RCA sub cable from my PW2200 and see what frequency my main speakers (Paradigm M7v2s) stopped at. You would think with them set to small( and they are I checked) that they would stop at around 90 hz...hence the crossover. But they don't at all. A decent audible sound was still coming out at 42.5 hz, and 38.5 hz. But wouldn't that be transferred to the subwoofer.
    Help me out here....am I missing something when it comes to the crossover in my receiver?
    Thanks in advance,
    Ryan P
    ------------------
    Oops, I dropped my eardrums.
    Could you pick them up for me?
     
  2. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    the crossovers are slopes,not brickwalls.
    if you had a 12dB/octave slope at 90hz...the signal will be attenuated 12dBs 1 octave under 90hz(45hz).
    TV
     
  3. bryan_chow

    bryan_chow Agent

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    It sounds like you were expecting the crossover to work like some kind of a notch filter?
    They don't work like that. Below the crossover frequency the sound gradually drops off.
    Bryan
     
  4. Graeme Shiomi

    Graeme Shiomi Stunt Coordinator

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    A crossover is not a brick wall, but gradually blends the high and low portions of the output. How gradually it happens will depend on the Order. First order is 6dB/Octave, second is 12db/octave, third is 18 etc. etc.
    I've got a Yamaha, and I think mine is a third order or second order. Whatever the case, what you heard was not outrageous. It does go to show you that even if you set your speakers to small, depending on the crossover, you still will benefit from a higher range of speaker.
    Graeme
     
  5. Ryan Peddle

    Ryan Peddle Second Unit

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    You know what the funny thing is. Everything you have told me is exactly what I learned today in class. I plotted Frequency vs Attn graphs today for RC, RL and RLC circuits. Thanks for the info guys.
    ------------------
    Oops, I dropped my eardrums.
    Could you pick them up for me?
     
  6. SkiingNinja

    SkiingNinja Second Unit

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    Yeah Graeme! Thanks! I always wondered what the "4th order" part of the description of my crossover meant.
    Sean
     

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