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

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 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. ClarityCap PX EUR 64,90 excl. VAT: € 54.54 / $ 58.90 EUR 53,70 excl. VAT: € 45.13 / $ 48.74 EUR 26,60 excl. VAT: € 22.35 / $ 24.14 EUR 29,00 excl. VAT: € 24.37 / $ 26.32 EUR 17,50 excl. VAT: € 14.71 / $ 15.88 EUR 13,80 excl. VAT: € 11.60 / $ 12.52 EUR 7,50 excl. VAT: € 6.30 / $ 6.81 EUR 10,50 excl. VAT: € 8.82 / $ 9.53 EUR 5,00 excl. VAT: € 4.20 / $ 4.54 EUR 11,70 excl. VAT: € 9.83 / $ 10.62
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 18,50 excl. VAT: € 15.55 / $ 16.79
H71
10 mH
0,87 Ohm EUR 15,50 excl. VAT: € 13.03 / $ 14.07
H71
6,8 mH
0,70 Ohm EUR 13,60 excl. VAT: € 11.43 / $ 12.34
H71
4,7 mH
0,46 Ohm EUR 12,60 excl. VAT: € 10.59 / $ 11.44
L100
3,3 mH
1,1Ohm EUR 29,30 excl. VAT: € 24.62 / $ 26.59
L100
2,2 mH
0,83 Ohm EUR 23,40 excl. VAT: € 19.66 / $ 21.24
L100
1,5 mH
0,62 Ohm EUR 19,50 excl. VAT: € 16.39 / $ 17.70
L100
1,00 mH
0,49 Ohm EUR 16,10 excl. VAT: € 13.53 / $ 14.61
L100
0,82 mH
0,44 Ohm EUR 14,60 excl. VAT: € 12.27 / $ 13.25
L100
0,56 mH
0,36 Ohm EUR 12,60 excl. VAT: € 10.59 / $ 11.44
Coils
up to 50 Watt
H100
15 mH
0,83 Ohm EUR 34,20 excl. VAT: € 28.74 / $ 31.04
H100
10 mH
0,64 Ohm EUR 29,30 excl. VAT: € 24.62 / $ 26.59
H100
6,8 mH
0,46 Ohm EUR 23,40 excl. VAT: € 19.66 / $ 21.24
H71
4,7 mH
0,46 Ohm EUR 12,60 excl. VAT: € 10.59 / $ 11.44
H100
3,3 mH
0,27 Ohm EUR 17,50 excl. VAT: € 14.71 / $ 15.88
L100
2,2 mH
0,83 Ohm EUR 23,40 excl. VAT: € 19.66 / $ 21.24
L100
1,5 mH
0,62 Ohm EUR 19,50 excl. VAT: € 16.39 / $ 17.70
L100
1,00 mH
0,49 Ohm EUR 16,10 excl. VAT: € 13.53 / $ 14.61
L100
0,82 mH
0,44 Ohm EUR 14,60 excl. VAT: € 12.27 / $ 13.25
L100
0,56 mH
0,36 Ohm EUR 12,60 excl. VAT: € 10.59 / $ 11.44
Coils
up to 100 Watt
BS125
15 mH
0,59 Ohm EUR 63,60 excl. VAT: € 53.45 / $ 57.72
BS125
10 mH
0,46 Ohm EUR 55,70 excl. VAT: € 46.81 / $ 50.55
BS125
6,8 mH
0,37 Ohm EUR 50,80 excl. VAT: € 42.69 / $ 46.10
BS125
4,7 mH
0,30 Ohm EUR 46,90 excl. VAT: € 39.41 / $ 42.56
H100
3,3 mH
0,27 Ohm EUR 17,50 excl. VAT: € 14.71 / $ 15.88
H100
2,2 mH
0,21 Ohm EUR 15,50 excl. VAT: € 13.03 / $ 14.07
H100
1,5 mH
0,17 Ohm EUR 13,60 excl. VAT: € 11.43 / $ 12.34
L140
1,00 mH
0,30 Ohm EUR 31,20 excl. VAT: € 26.22 / $ 28.32
L140
0,82 mH
0,26 Ohm EUR 28,30 excl. VAT: € 23.78 / $ 25.68
L140
0,56 mH
0,2 Ohm EUR 23,40 excl. VAT: € 19.66 / $ 21.24
Coils
up to 180 Watt
PA-Trafo
mo-123200
0,12 Ohm EUR 89,00 excl. VAT: € 74.79 / $ 80.77
PA-Trafo
mo-125490
0,19 Ohm EUR 30,12 excl. VAT: € 25.31 / $ 27.34
PA-Trafo
mo-125470
0,16 Ohm EUR 31,41 excl. VAT: € 26.39 / $ 28.51
H140
4,7 mH
0,26 Ohm EUR 38,10 excl. VAT: € 32.02 / $ 34.58
H140
3,3 mH
0,19 Ohm EUR 32,20 excl. VAT: € 27.06 / $ 29.22
H140
2,2 mH
0,14 Ohm EUR 25,30 excl. VAT: € 21.26 / $ 22.96
H140
1,5 mH
0,11 Ohm EUR 21,40 excl. VAT: € 17.98 / $ 19.42
L140
1,00 mH
0,30 Ohm EUR 31,20 excl. VAT: € 26.22 / $ 28.32
L140
0,82 mH
0,26 Ohm EUR 28,30 excl. VAT: € 23.78 / $ 25.68
L140
0,56 mH
0,2 Ohm EUR 23,40 excl. VAT: € 19.66 / $ 21.24
Coils
up to 330 Watt
PA-Trafo
mo-123200
0,12Ohm EUR 89,00 excl. VAT: € 74.79 / $ 80.77
PA-Trafo
mo-125490
0,19Ohm EUR 30,12 excl. VAT: € 25.31 / $ 27.34
PA-Trafo
mo-125470
0,16Ohm EUR 31,41 excl. VAT: € 26.39 / $ 28.51
PA-Trafo
mo-125450
0,14Ohm EUR 29,28 excl. VAT: € 24.61 / $ 26.57
BT140
3,3 mH
0,22 Ohm EUR 88,10 excl. VAT: € 74.03 / $ 79.96
BS140
2,2 mH
0,16 Ohm EUR 37,10 excl. VAT: € 31.18 / $ 33.67
BS140
3,3 mH
0,12 Ohm EUR 34,20 excl. VAT: € 28.74 / $ 31.04
H140
1,0 mH
0,08Ohm EUR 18,50 excl. VAT: € 15.55 / $ 16.79
H180
0,82 mH
0,06 Ohm EUR 93,00 excl. VAT: € 78.15 / $ 84.40
H180
0,56 mH
0.05 Ohm EUR 28,30 excl. VAT: € 23.78 / $ 25.68
Coils
up to 550 Watt
PA-Trafo
mo-123200
0,12Ohm EUR 89,00 excl. VAT: € 74.79 / $ 80.77
VT180
10 mH
0,27 Ohm EUR 161,60 excl. VAT: € 135.80 / $ 146.66
VT180-68
6,8 mH
0,21 Ohm EUR 151,80 excl. VAT: € 127.56 / $ 137.77
VT180
4,7 mH
0,17 Ohm EUR 127,30 excl. VAT: € 106.97 / $ 115.53
VT180
3,3 mH
0,14 Ohm EUR 117,50 excl. VAT: € 98.74 / $ 106.64
BT140
2,2 mH
0,12 Ohm EUR 78,30 excl. VAT: € 65.80 / $ 71.06
BT140
1,5 mH
0,09 Ohm EUR 62,60 excl. VAT: € 52.61 / $ 56.81
L200
1,0 mH
0,18 Ohm EUR 44,00 excl. VAT: € 36.97 / $ 39.93
H180
0,82 mH
0,06 Ohm EUR 93,00 excl. VAT: € 78.15 / $ 84.40
H180
0,56 mH
0,05 Ohm EUR 28,30 excl. VAT: € 23.78 / $ 25.68
Coils
up to 1000 Watt
T236
15 mH
0,24 Ohm EUR 209,90 excl. VAT: € 176.39 / $ 190.50
T236
10 mH
0,18 Ohm EUR 189,90 excl. VAT: € 159.58 / $ 172.35
T236
6,8 mH
0,14 Ohm EUR 179,90 excl. VAT: € 151.18 / $ 163.27
T236
4,7 mH
0,12 Ohm EUR 134,90 excl. VAT: € 113.36 / $ 122.43
T236
3,3 mH
0,10 Ohm EUR 126,90 excl. VAT: € 106.64 / $ 115.17
BT180
2,2 mH
0,11 Ohm EUR 107,70 excl. VAT: € 90.50 / $ 97.74
BT180
1,5 mH
0,09 Ohm EUR 88,10 excl. VAT: € 74.03 / $ 79.96
BT180
1,0 mH
0,08 Ohm EUR 84,10 excl. VAT: € 70.67 / $ 76.33
VT236
0,82 mH
0,06 Ohm EUR 146,90 excl. VAT: € 123.45 / $ 133.32
VT236
0,56 mH
0,08 Ohm EUR 117,50 excl. VAT: € 98.74 / $ 106.64

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.
 

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