How to find crossover frequency?

Discussion in 'Speakers & Subwoofers' started by Schnitz, Jan 11, 2005.

  1. Schnitz

    Schnitz Auditioning

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    I have an H/K AVR130 and I am trying to figure out the crossover settings. Everything is set to 100hz as a default. I have Polk R30 fronts, a CSI3 center, R15 rears and a Dayton Sub ($99 one). I tried to post links to the specs for the speakers but I have too few posts to be allowed to. I am new to Home Theater - as you can tell by my system - and have found this site unbelievably informative. I have tried the search feature to no avail. Please help figure out how to find the information I need from the speaker specs or direct me to a resource that can. Thanks.
     
  2. Morgan_

    Morgan_ Stunt Coordinator

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    Hello. Your specs on your speakers run: Overall Frequency Response 45Hz - 24kHz and a +/-3 lower range to 55hz, so I'd try your setting at 60hz, your dayton sub will handle whatever it can below 60hz. Try 60hz, and try 80hz settings and which ever sounds best on the low end, I'd go with that.
     
  3. Kevin C Brown

    Kevin C Brown Producer

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    If the -3 dB point is 55 Hz, then 60 Hz is probably too low. The problem is then that the slope of the roll off of the speaker will add to the slope imposed by the crossover. Because of that, you will most likely get a dip in response near the crossover setting. A good rule of thumb is to put the crossover setting 1/2 to a full octave above the -3 dB point of the speaker. That way, the roll off of the speaker is more or less nowhere near the imposed slope of the crossover. 1/2 an octave up from 55 Hz is 55 + 1/2 of 55 Hz = about 80 Hz.

    The only real exception to this is THX certified speakers, whereby the roll off of the speaker is *designed* to be added to the slope of the THX 80 Hz crossover setting in a THX certified receiver or pre/pro.
     
  4. Rob Kramer

    Rob Kramer Second Unit

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    The speakers should be able to handle (f3) 1 octive below the crossover freq. The sub should be able to handle 1 octive above the crossover freq.

    Thats about 100Hz (110 actually), but try out 80Hz also since your sub probably cant integrate seemlessly at the correct value.
     
  5. GregBe

    GregBe Second Unit

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    I think it is a lot like going to the eye doctor, and he asks "which looks better, A or B". Once you get it close, the differences will be subtle. You really need to compare for yourself. I think 1/2 octave is a good rule of thumb. A full octave may be pertinant if you are talking about floorstanding speakers, but for bookshelf speakers and satellites, I would start with 1/2 octave.

    Some material I have used that really helped me. For the mains, I would use music in stereo. You want to use something that plays in the crossover region. Jazz with accoustic bass works great for this.

    For the center channel, play some isolated deep male voices. There is a scene in The Patriot, where Mel Gibson is in Cornwallis' office trying to negotiate the freeing of the hostages. Listen to the differences in his voice between 80 and 100 crossovers. Also in the beginning of X2, there is a voiceover by Patrick Stewart that is isolated. The center channel does a lot in theater, but in my opinion, voices are the most important. I strive to get this right.

    By the way, both my mains and center have an F3 of 65 Hz, and I have my crossover set at 100.

    Greg
     
  6. Kevin C Brown

    Kevin C Brown Producer

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    I like how you worded this. This is exactly how my system is set up. [​IMG] "Full" range floorstanders for front L & R, and then not "full" range center, surrounds, and rears.
     

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