Is this speaker crossover OK?

Discussion in 'The Projects Forum' started by cumesoftware, Jun 23, 2009.

  1. cumesoftware

    Thread Starter Senior Member

    Apr 27, 2007
    1,330
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    This is a crossover for the "Taurus" project. These are intended to be mid-end and relatively cheap speakers. However it is my wish to submit it here too for a final revision. My questions are?

    Are the values OK?

    Is the phase shift of 180º between the woofer and the tweeter correctly assumed (note the tweeter "polarity" reversal when compared to the woofer)?

    C1/3 – Capacitor Visaton ELKO spez. 3,3µF;
    C2 – Capacitor Visaton ELKO spez. 15µF;
    C4 – Capacitor Visaton ELKO spez. 6.8µF;
    FTE1 – Tweeter Visaton SC 10 N 8 OHM;
    FTE2 – Woofer Visaton SC 13 8 OHM;
    J – RCA plug;
    L1-3 – Coil Visaton SP 0,47mH 0,6mm;
    R1 – 6,8Ω carbon resistor (5% tol., 1W);
    R2 – 10Ω carbon resistor (5% tol., 2W).

    You can see the schematic diagram in the attached PDF file.

    I really need a third opinion on this. Thanks in advance.
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,733
    759
    U know what I think of passive crossovers. It's nothing.
    But since you cannot go about building active crossovers, here is my opinion
    First is that passive crossovers are standardized for a particular speaker and numerous testing is done in an test room for proper phase alignment and all the anomalies that are introduced due to passive crossovers
    So if you are testing by your ears then you are not gonna hear any difference unless the signal is played in stereo mode.
    Only in stereo mode phase cancellatiobn creates dips in the sound.
    Point is that if you are not using a pair but just a woofer and a tweeter than phase shift is not much of a problem to the human ears.
    But an active crossover can really change you view towards crossovers.

    Rifaa

     
  3. Audioguru

    New Member

    Dec 20, 2007
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    896
    The little 5" midrange speaker does not have much bass.
    I couldn't find a datasheet for the tweeter to see if it is at the same level.

    Inverting one speaker to make them in phase results in a +3dB boost at the crossover frequency.
     
  4. cumesoftware

    Thread Starter Senior Member

    Apr 27, 2007
    1,330
    10
    Both of them have a sensitivity of 90dB. Here is the "datasheet" for the tweeter:
    http://www.visaton.de/en/chassis_zubehoer/geschirmt/sc10n_8.html

    About the bass, there is not much to do. A good and well tuned enclosure will minimize that. The frequency response is measured in free air.

    Indeed, since it is a Butterworth filter. So the speakers are oriented correctly, right? I just need to confirm if the phase shift is 180º between both speakers, which seems a bit odd in a second order crossover.
     
  5. cumesoftware

    Thread Starter Senior Member

    Apr 27, 2007
    1,330
    10
    Just came to the conclusion that the series notch filter is not necessary. R1, L2 and C2 were taken out. Other components were renamed.

    C1/2 – Capacitor Visaton ELKO spez. 3.3µF;
    C3 – Capacitor Visaton ELKO spez. 10µF;
    FTE1 – Tweeter Visaton SC 10 N 8 OHM;
    FTE2 – Woofer Visaton SC 13 8 OHM;
    J – RCA plug;
    L1/2 – Coil Visaton SP 0,47mH 0,6mm;
    R – 8.2Ω wirewound resistor (5% tol., 3W).

    You can see the new schematic diagram in the attached file.
     
    Last edited: Jun 24, 2009
  6. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    You are making an even-order Butterworth crossover filter that produces a +3dB peak at the crossover frequency. You should use a Linkwitz-Riley crossover filter circuit instead that does not have the peak. It uses Bessel filters instead of Butterworth.
    Here is a Linkwitz-Riley active crossover circuit: http://www.sound.westhost.com/project81.htm

    You should use an 8 inch woofer for much better and deeper bass.
     
  7. cumesoftware

    Thread Starter Senior Member

    Apr 27, 2007
    1,330
    10
    Thanks! I corrected that, and now I use a Bessel crossover.
     
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