The Design of a 2 way crossover for 8 Ohm loudspeakers    4 Ohm crossover

Frequenzweiche für 2-Weges-System oder Subwoofer If you want to calculate the crossover yourself:
2 way crossover calculator
Multiple driver crossover calculator.

For a 2 way system or to separate satellites from a subwoofer a 12 dB / octave filter according to the picture on the left should be used. For 8 Ohm systems the values of the following tables are applicable.

To choose a capacitor is straight forward: select the value from the table below and choose a capacitor according to the desired quality level. Standard means: a MKT in series to the tweeter and an unetched electrolytic capacitor in parallel to the woofer (in high powered PA application possibly a MKT). Please take into account the maximum voltage Vac:

  • up to 100 Watt: 35 Volt
  • up to 200 Watt: 50 Volt
  • up to 400 Watt: 70 Volt
  • up to 800 Watt: 100 Volt

    Selecting the right coil is a bit more complicated. Important aspects are:

  • The saturation, if it's not an air core coil (core coils lose their characteristics when overdriven),
  • the maximum power handling (possibly causing overheating!)
  • the coil's inner resistance which shouldn't be too high. A coil with a too high value and mounted in parallel to the bass drivers causes the driver's magnet to weaken, resulting in a loose and boomy bass.

    Taking these aspects into consideration, we suggest the coils listed in the table below, indicating coil type, order no and DC resistance.

    The colour code indicates the coil's material:
    - iron, high power handling
    - ferrite, low distortion - even at low volume
    - ferrite, T-Core with extremely low distortion
    - air, type 1 or 2 with lowest distortion
    - large air core coil, type 3 or 4, with lowest distortion

    For 8 Ohm loudspeakers:         ... 4 Ohm calculation  

    Frequency in Hz 120 180 270 400 550 800 1250 1800 2300 3100
    Cap. C in uF 100 82 47 33 22 15 10 6.8 5.6 4.7
    e.g. Clarity Cap PWA EUR 27,50 EUR 23,15 EUR 12,59 EUR 9,25 EUR 7,16 EUR 4,76 EUR 3,92 EUR 3,21 EUR 3,21 EUR 2,40
    Coil L in mH 15 10 6.8 4.7 3.3 2.2 1.5 1.0 0.82 0.56
    Coils
    up to 25 Watt    		 H71
    15 mH
    1,2 Ohm EUR 11,70     		H71
    10 mH
    0,87 Ohm EUR 10,70     		H71
    6,8 mH
    0,70 Ohm EUR 8,85     		H71
    4,7 mH
    0,46 Ohm EUR 8,45     		L100
    3,3 mH
    1,1Ohm EUR 10,70     		L100
    2,2 mH
    0,83 Ohm EUR 8,85     		L100
    1,5 mH
    0,62 Ohm EUR 7,35     		L100
    1,00 mH
    0,49 Ohm EUR 6,35     		L100
    0,82 mH
    0,44 Ohm EUR 5,85     		L100
    0,56 mH
    0,36 Ohm EUR 5,25
    Coils
    up to 50 Watt    		 H100
    15 mH
    0,83 Ohm EUR 19,60     		H100
    10 mH
    0,64 Ohm EUR 17,60     		H100
    6,8 mH
    0,46 Ohm EUR 14,30     		H71
    4,7 mH
    0,46 Ohm EUR 8,45     		H100
    3,3 mH
    0,27 Ohm EUR 12,30     		L100
    2,2 mH
    0,83 Ohm EUR 8,85     		L100
    1,5 mH
    0,62 Ohm EUR 7,35     		L100
    1,00 mH
    0,49 Ohm EUR 6,35     		L100
    0,82 mH
    0,44 Ohm EUR 5,85     		L100
    0,56 mH
    0,36 Ohm EUR 5,25
    Coils
    up to 100 Watt    		 BS125
    15 mH
    0,59 Ohm EUR 33,20     		BS125
    10 mH
    0,46 Ohm EUR 30,20     		BS125
    6,8 mH
    0,37 Ohm EUR 28,30     		BS125
    4,7 mH
    0,30 Ohm EUR 26,30     		H100
    3,3 mH
    0,27 Ohm EUR 12,30     		H100
    2,2 mH
    0,21 Ohm EUR 10,70     		H100
    1,5 mH
    0,17 Ohm EUR 8,65     		L140
    1,00 mH
    0,30 Ohm EUR 11,70     		L140
    0,82 mH
    0,26 Ohm EUR 10,70     		L140
    0,56 mH
    0,2 Ohm EUR 9,35
    Coils
    up to 180 Watt    		 PA-Trafo
    mo-123200
    0,12 Ohm EUR 87,80     		PA-Trafo
    mo-125490
    0,19 Ohm EUR 30,00     		PA-Trafo
    mo-125470
    0,16 Ohm EUR 27,70     		H140
    4,7 mH
    0,26 Ohm EUR 19,60     		H140
    3,3 mH
    0,19 Ohm EUR 18,60     		H140
    2,2 mH
    0,14 Ohm EUR 13,70     		H140
    1,5 mH
    0,11 Ohm EUR 12,30     		L140
    1,00 mH
    0,30 Ohm EUR 11,70     		L140
    0,82 mH
    0,26 Ohm EUR 10,70     		L140
    0,56 mH
    0,2 Ohm EUR 9,35
    Coils
    up to 330 Watt    		 PA-Trafo
    mo-123200
    0,12Ohm EUR 87,80     		PA-Trafo
    mo-125490
    0,19Ohm EUR 30,00     		PA-Trafo
    mo-125470
    0,16Ohm EUR 27,70     		PA-Trafo
    mo-125450
    0,14Ohm EUR 25,80     		BT140
    3,3 mH
    0,22 Ohm EUR 50,90     		BS140
    2,2 mH
    0,16 Ohm EUR 24,00     		BS140
    3,3 mH
    0,12 Ohm EUR 20,40     		H140
    1,0 mH
    0,08Ohm EUR 11,30     		L200
    0,82 mH
    0,16 Ohm EUR 29,55     		L200
    0,56 mH
    0,11 Ohm EUR 23,65
    Coils
    up to 550 Watt    		 PA-Trafo
    mo-123200
    0,12Ohm EUR 87,80     		T250
    10 mH
    0,16 Ohm EUR 123,00     		T250
    6,8 mH
    0,12 Ohm EUR 111,00     		T250
    4,7 mH
    0,08 Ohm EUR 102,00     		T200
    3,3 mH
    0,10 Ohm EUR 70,90     		BT140
    2,2 mH
    0,12 Ohm EUR 48,35     		BT140
    1,5 mH
    0,09 Ohm EUR 35,45     		L200
    1,0 mH
    0,18 Ohm EUR 32,55     		L200
    0,82 mH
    0,16 Ohm EUR 29,55     		L200
    0,56 mH
    0,11 Ohm EUR 23,65
    Coils
    up to 1000 Watt    		 T250
    15 mH
    0,17 Ohm EUR 152,00     		T250
    10 mH
    0,16 Ohm EUR 123,00     		T250
    6,8 mH
    0,12 Ohm EUR 111,00     		T250
    4,7 mH
    0,08 Ohm EUR 102,00     		T200
    3,3 mH
    0,10 Ohm EUR 70,90     		T200
    2,2 mH
    0,09 Ohm EUR 63,90     		T200
    1,5 mH
    0,09 Ohm EUR 52,90     		L250
    1,0 mH
    0,12 Ohm EUR 50,90     		L250
    0,82 mH
    0,10 Ohm EUR 47,35     		L250
    0,56 mH
    0,08 Ohm EUR 41,45

    Both, the two coils and the two capacitors, should have the values indicated in the table. A subwoofer filter requires only one capacitor and one coil.

    The coil in parallel to the tweeter or satellite needs to handle only half / a quarter of the power, if the crossover frequency is higher than 400/800 Hz.

    Hint:

    1) 18 and 24 dB / octave crossovers only make sense when the driver's exact characteristics are known!

    2) This is certainly not a high-end-crossover. Such a crossover needs to be designed according to the drivers used. A good example is the EX2 MAG-crossover.
     

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