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

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

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

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 4 Ohm loudspeakers:         ... 8 Ohm calculation  

Frequency in Hz 60 90 135 200 275 400 625 900 1200 1500
Cap. C in uF 400 330 200 100 82 68 47 33 22 15
e.g. ClarityCap PWA 4x EUR 31,20 excl. VAT: € 26.22 / $ 30.94 4x EUR 26,30 excl. VAT: € 22.10 / $ 26.08 2x EUR 31,20 excl. VAT: € 26.22 / $ 30.94 EUR 31,20 excl. VAT: € 26.22 / $ 30.94 EUR 26,30 excl. VAT: € 22.10 / $ 26.08 EUR 23,00 excl. VAT: € 19.33 / $ 22.81 EUR 16,70 excl. VAT: € 14.03 / $ 16.56 EUR 9,90 excl. VAT: € 8.32 / $ 9.82 EUR 7,60 excl. VAT: € 6.39 / $ 7.54 EUR 5,10 excl. VAT: € 4.29 / $ 5.06
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 12 Watt
H71
15 mH
1,2 Ohm EUR 15,50 excl. VAT: € 13.03 / $ 15.37
H71
10 mH
0,87 Ohm EUR 11,50 excl. VAT: € 9.66 / $ 11.40
H71
6,8 mH
0,70 Ohm EUR 10,20 excl. VAT: € 8.57 / $ 10.11
H71
4,7 mH
0,46 Ohm EUR 9,30 excl. VAT: € 7.82 / $ 9.22
L100
3,3 mH
1,1Ohm EUR 19,30 excl. VAT: € 16.22 / $ 19.14
L100
2,2 mH
0,83 Ohm EUR 16,40 excl. VAT: € 13.78 / $ 16.26
L100
1,5 mH
0,62 Ohm EUR 13,50 excl. VAT: € 11.34 / $ 13.39
L100
1,00 mH
0,49 Ohm EUR 11,60 excl. VAT: € 9.75 / $ 11.50
L100
0,82 mH
0,44 Ohm EUR 10,60 excl. VAT: € 8.91 / $ 10.51
L100
0,56 mH
0,36 Ohm EUR 9,20 excl. VAT: € 7.73 / $ 9.12
Coils
up to 25 Watt
H100
15 mH
0,83 Ohm EUR 28,20 excl. VAT: € 23.70 / $ 27.96
H100
10 mH
0,64 Ohm EUR 24,30 excl. VAT: € 20.42 / $ 24.10
H100
6,8 mH
0,46 Ohm EUR 19,20 excl. VAT: € 16.13 / $ 19.04
H71
4,7 mH
0,46 Ohm EUR 9,30 excl. VAT: € 7.82 / $ 9.22
H100
3,3 mH
0,27 Ohm EUR 15,40 excl. VAT: € 12.94 / $ 15.27
L100
2,2 mH
0,83 Ohm EUR 16,40 excl. VAT: € 13.78 / $ 16.26
L100
1,5 mH
0,62 Ohm EUR 13,50 excl. VAT: € 11.34 / $ 13.39
L100
1,00 mH
0,49 Ohm EUR 11,60 excl. VAT: € 9.75 / $ 11.50
L100
0,82 mH
0,44 Ohm EUR 10,60 excl. VAT: € 8.91 / $ 10.51
L100
0,56 mH
0,36 Ohm EUR 9,20 excl. VAT: € 7.73 / $ 9.12
Coils
up to 50 Watt
BS125
15 mH
0,59 Ohm EUR 55,20 excl. VAT: € 46.39 / $ 54.74
BS125
10 mH
0,46 Ohm EUR 46,70 excl. VAT: € 39.24 / $ 46.31
BS125
6,8 mH
0,37 Ohm EUR 44,80 excl. VAT: € 37.65 / $ 44.42
BS125
4,7 mH
0,30 Ohm EUR 42,80 excl. VAT: € 35.97 / $ 42.44
H100
3,3 mH
0,27 Ohm EUR 15,40 excl. VAT: € 12.94 / $ 15.27
H100
2,2 mH
0,21 Ohm EUR 11,10 excl. VAT: € 9.33 / $ 11.01
H100
1,5 mH
0,17 Ohm EUR 9,70 excl. VAT: € 8.15 / $ 9.62
L140
1,00 mH
0,30 Ohm EUR 19,30 excl. VAT: € 16.22 / $ 19.14
L140
0,82 mH
0,26 Ohm EUR 18,30 excl. VAT: € 15.38 / $ 18.15
L140
0,56 mH
0,2 Ohm EUR 16,50 excl. VAT: € 13.87 / $ 16.36
Coils
up to 90 Watt
PA-Trafo
mo-123200
0,12 Ohm EUR 74,70 excl. VAT: € 62.77 / $ 74.07
PA-Trafo
mo-125490
0,19 Ohm EUR 27,70 excl. VAT: € 23.28 / $ 27.47
PA-Trafo
mo-125470
0,16 Ohm EUR 26,50 excl. VAT: € 22.27 / $ 26.28
H140
4,7 mH
0,26 Ohm EUR 29,20 excl. VAT: € 24.54 / $ 28.95
H140
3,3 mH
0,19 Ohm EUR 27,30 excl. VAT: € 22.94 / $ 27.07
H140
2,2 mH
0,14 Ohm EUR 21,30 excl. VAT: € 17.90 / $ 21.12
H140
1,5 mH
0,11 Ohm EUR 18,30 excl. VAT: € 15.38 / $ 18.15
L140
1,00 mH
0,30 Ohm EUR 19,30 excl. VAT: € 16.22 / $ 19.14
L140
0,82 mH
0,26 Ohm EUR 18,30 excl. VAT: € 15.38 / $ 18.15
L140
0,56 mH
0,2 Ohm EUR 16,50 excl. VAT: € 13.87 / $ 16.36
Coils
up to 165 Watt
PA-Trafo
mo-123200
0,12Ohm EUR 74,70 excl. VAT: € 62.77 / $ 74.07
PA-Trafo
mo-125490
0,19Ohm EUR 27,70 excl. VAT: € 23.28 / $ 27.47
PA-Trafo
mo-125470
0,16Ohm EUR 26,50 excl. VAT: € 22.27 / $ 26.28
PA-Trafo
mo-125450
0,14Ohm EUR 23,00 excl. VAT: € 19.33 / $ 22.81
BT140
3,3 mH
0,22 Ohm EUR 77,90 excl. VAT: € 65.46 / $ 77.25
BS140
2,2 mH
0,16 Ohm EUR 36,80 excl. VAT: € 30.92 / $ 36.49
BS140
3,3 mH
0,12 Ohm EUR 33,90 excl. VAT: € 28.49 / $ 33.62
H140
1,0 mH
0,08Ohm EUR 16,40 excl. VAT: € 13.78 / $ 16.26
L200
0,82 mH
0,16 Ohm EUR 38,90 excl. VAT: € 32.69 / $ 38.57
L200
0,56 mH
0,11 Ohm EUR 31,10 excl. VAT: € 26.13 / $ 30.84
Coils
up to 275 Watt
PA-Trafo
mo-123200
0,12Ohm EUR 74,70 excl. VAT: € 62.77 / $ 74.07
T250
10 mH
0,16 Ohm EUR 200,00 excl. VAT: € 168.07 / $ 198.32
T250
6,8 mH
0,12 Ohm EUR 190,00 excl. VAT: € 159.66 / $ 188.40
T250
4,7 mH
0,08 Ohm EUR 176,00 excl. VAT: € 147.90 / $ 174.52
T200
3,3 mH
0,10 Ohm EUR 106,00 excl. VAT: € 89.08 / $ 105.11
BT140
2,2 mH
0,12 Ohm EUR 72,00 excl. VAT: € 60.50 / $ 71.39
BT140
1,5 mH
0,09 Ohm EUR 60,20 excl. VAT: € 50.59 / $ 59.69
L200
1,0 mH
0,18 Ohm EUR 43,70 excl. VAT: € 36.72 / $ 43.33
L200
0,82 mH
0,16 Ohm EUR 38,90 excl. VAT: € 32.69 / $ 38.57
L200
0,56 mH
0,11 Ohm EUR 31,10 excl. VAT: € 26.13 / $ 30.84
Coils
up to 500 Watt
T250
15 mH
0,17 Ohm EUR 243,00 excl. VAT: € 204.20 / $ 240.96
T250
10 mH
0,16 Ohm EUR 200,00 excl. VAT: € 168.07 / $ 198.32
T250
6,8 mH
0,12 Ohm EUR 190,00 excl. VAT: € 159.66 / $ 188.40
T250
4,7 mH
0,08 Ohm EUR 176,00 excl. VAT: € 147.90 / $ 174.52
T200
3,3 mH
0,10 Ohm EUR 106,00 excl. VAT: € 89.08 / $ 105.11
T200
2,2 mH
0,09 Ohm EUR 91,30 excl. VAT: € 76.72 / $ 90.53
T200
1,5 mH
0,09 Ohm EUR 78,20 excl. VAT: € 65.71 / $ 77.54
L250
1,0 mH
0,12 Ohm EUR 63,30 excl. VAT: € 53.19 / $ 62.77
L250
0,82 mH
0,10 Ohm EUR 60,10 excl. VAT: € 50.50 / $ 59.59
L250
0,56 mH
0,08 Ohm EUR 50,10 excl. VAT: € 42.10 / $ 49.68

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 Cauchy-crossover.
 

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