Crossover Frequencies

Discussion in 'AV Receivers' started by MarkStash, Jan 14, 2004.

  1. MarkStash

    MarkStash Stunt Coordinator

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    I am still feeling my way, trying to understand the basics....go easy on me [​IMG] Can someone explain the concept to me, in terms that my simple mind can comprehend?

    For example, my main speaker's specs read:

    Crossover frequency: 600Hz, 2500Hz; 24dB/octave

    The center (which I am looking to upgrade and led to this thread) reads:

    Crossover frequency: 2000 Hz, 24dB/octave

    So, what is this telling me and what do I need to know to make an informed decision? Again, go easy.....thanks.

    Mark
     
  2. John S

    John S Producer

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    It is telling you that your Mains are 3 ways, and your center is a two way.


    What informed decision are you try'n to make?????
     
  3. JohnSmith

    JohnSmith Supporting Actor

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    That is the crossover frequencies of the treble midrange and bass drivers. Not the overall frequency response of the speakers ie 50hz-20khz.

    You would set your av amps xover higher than the speaker's ability to reproduce bass.. so for the above example (50hz LF corner) you would set to 60,70 or 80hz.
     
  4. chung_sotheby

    chung_sotheby Supporting Actor

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    John is correct. To put it in more technical terms:

    You main speakers have three drivers: the tweeter, the midrange, and the woofer. What the crossover frequency specs are telling you is that in your main speakers, the woofer and midrange are crossed over at 600 hz, with a slope of 24 dB/octave. What this means is that all information above 600hz is taken out of the woofer at 24 db/octave. What the db/octave means is that sound from your woofer at 1200 Hz is 24dB below that of the 600hz sound, and that sound at 2400 hz from the woofer is 48dB below that of the 600 Hz sound. Conversely, all information below 600 Hz is taken away from the midrange at the same 24 Db/octave. An octave above is a doubling of Hz, while an octave below is a halving of Hz. Now the same principle applies with the crossover point between the midrange and the tweeter. All sound above 2500 Hz is being taken away from the midrange at 24dB/octave, while all sound below 2500 Hz is taken away from the tweeter.

    Your center only has one crossover specification because there are only two types of drivers in it, the woofer and the tweeter. While you may have three drivers in the cabinet (such as a woofer-tweeter-woofer array, which is very popular among center designs) these are only two types of drivers, with two of one type (woofer) and one of another (tweeter)

    Now what you do with this information is up in the air, since your post is rather open ended. The only use I see with this information is if you would like to biamp or triamp you mains or center, but that is a whole nother can of worms. Hope this helped
     
  5. MarkStash

    MarkStash Stunt Coordinator

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    Thanks guys....I'm trying.

    Sorry about the open-ended post. What I'm trying to do is find a decent center to go with my Infinity IL-40s and my Infinity IL-120S sub and Denon 3803 receiver. I have an Infinity Entra Center Two (center) and I just think I'm unhappy with it. So, in addition to attempting to understand what the specs mean, I'm trying to associate the information to "match" speakers.

    I've considered getting the Infinity IL-36C as my room is large and it should match well but I keep thinking that if I knew more/understood more I'd be making better decisions. Again, thanks and if you have ideas I'd love to have 'em.

    Mark
     
  6. John S

    John S Producer

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    Timbre matching is tough....

    Short of try'n something, with the understanding it can be returned if it does not work out, there isn't any good way to do it.

    I don't like center specific speakers all to much, I tend to use the exact same speaker all the way around.

    I would suggest another IL-40
     
  7. Brian L

    Brian L Cinematographer

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    The problem with matching the center is that the specs will not tell you anything about how its voiced, and thats the critical parameter.

    Is the IL-36 you mentioned designed to match the IL-40's? If so, that what you want to get.

    Even staying within the same brand is not enough. You need to stay within the same brand and the same model line for optinal match.

    Well, really, you should use the exact same speaker in all 5 (or 6 or 7!) locations, but most folks can't deal with a vertical center, so the matching center is the next best thing.

    BGL
     
  8. MarkStash

    MarkStash Stunt Coordinator

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    John and Brian:

    You've helped alot. I think I stay with the Infinity line, see what the best center match was and probably go that way. A four foot IL-40 on top of the big screen probably isn't going to work...... You've got me headed down the right path....thanks.
     

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