Need LinkWitz Riley Band Pass Filter @ 24 db/oct

Discussion in 'Homework Help' started by Ealireza, Jun 19, 2009.

  1. Ealireza

    Thread Starter New Member

    Jun 19, 2009
    3
    0
    Hi
    Is Possible Some Body Design Circuit for me ?

    I need Variable Band Pass Filter

    HPF : From 25 To 500 HZ
    Lpf : From 100 To 500 HZ

    I need It @ 24 DB /Octav Slope .

    I dont know How can be Make it as variable Cutoff Selector..
    .

    Regards,
    Alireza
     
    Last edited: Jun 19, 2009
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    A variable frequency 24db/octave filter needs four pots to change at the same time.
    The frequencies are so close together that the highpass will affect the output of the lowpass and the lowpass will affect the output of the highpass.
     
  3. Ealireza

    Thread Starter New Member

    Jun 19, 2009
    3
    0
    dear Audioguru
    i know it need to change capacitor for 4 one order Linkwitz Circuit .
    but i want to know how can i do this :d ?

    i want use this Filter on different propose

    for example for Subwoofer I use it on Band Pass : 30HZ to 120 HZ
    for Midbassess : 100 to 500 Hz
    and ...

    for Full Range Speaker LPF filter will be Off .

    This is Like Car Amplifire .

    Let me show you Filter Board of Sound Stream Tra 680.4 Class A/b amplifier
    http://img.majidonline.com/show/202425/BandpassFilter.png

    It Selectable Hi/Low Pass Filter With Variable Frequency Selector

    I Interested To create one of Them

    Please Guidance me :)

    Sorry for my bad English :(

    Regards ,
    Alireza
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    A sub-woofer uses a lowpass filter, not a bandpass filter.

    A Linkwitz-Riley 4th-order bandpass filter will have 100Hz at -6dB, 225Hz at -1dB and 500Hz at -6dB. Why bother with a mid-bass speaker? A full-range speaker can easily go down to 100Hz. Then use a 4th-order highpass filter at 100Hz for it.
     
  5. Ealireza

    Thread Starter New Member

    Jun 19, 2009
    3
    0
    To Prevent High Excursion and Extra Woofer Cone Excursion
    use SubSonic/InfraSonic Filter : HighPass Filter From 15 - 40 HZ [Frequency Is Selectable based on Enclosure Tune Frequency]
    It's very important for Ported Enclosure

    Extra Excursion May be Damage Cone , Spider , Woofer , ....
    It Help Amplifire To Oprate On Higher and hearable Frequency
    and prevent amplifier to Waste Power
    Clear Sound
    ,.....

    So , We Need Band Pass Filter For Woofer to prevent Getting damage To subwoofer and helping amplifier Performance :)
     
    Last edited: Jun 20, 2009
  6. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    OK, your sub-woofer is too small to produce 20Hz so use a highpass filter which is part of a bandpass filter to cut deep bass frequencies.
     
Loading...