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 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 16,90
H71
10 mH
0,87 Ohm EUR 16,00
H71
6,8 mH
0,70 Ohm EUR 15,00
H71
4,7 mH
0,46 Ohm EUR 13,50
L100
3,3 mH
1,1Ohm EUR 13,40
L100
2,2 mH
0,83 Ohm EUR 10,50
L100
1,5 mH
0,62 Ohm EUR 9,05
L100
1,00 mH
0,49 Ohm EUR 8,05
L100
0,82 mH
0,44 Ohm EUR 7,55
L100
0,56 mH
0,36 Ohm EUR 6,75
Coils
up to 50 Watt
H100
15 mH
0,83 Ohm EUR 29,05
H100
10 mH
0,64 Ohm EUR 27,15
H100
6,8 mH
0,46 Ohm EUR 16,20
H71
4,7 mH
0,46 Ohm EUR 13,50
H100
3,3 mH
0,27 Ohm EUR 14,30
L100
2,2 mH
0,83 Ohm EUR 10,50
L100
1,5 mH
0,62 Ohm EUR 9,05
L100
1,00 mH
0,49 Ohm EUR 8,05
L100
0,82 mH
0,44 Ohm EUR 7,55
L100
0,56 mH
0,36 Ohm EUR 6,75
Coils
up to 100 Watt
BS125
15 mH
0,59 Ohm EUR 42,55
BS125
10 mH
0,46 Ohm EUR 40,65
BS125
6,8 mH
0,37 Ohm EUR 38,75
BS125
4,7 mH
0,30 Ohm EUR 36,75
H100
3,3 mH
0,27 Ohm EUR 14,30
H100
2,2 mH
0,21 Ohm EUR 14,00
H100
1,5 mH
0,17 Ohm EUR 13,40
L140
1,00 mH
0,30 Ohm EUR 14,40
L140
0,82 mH
0,26 Ohm EUR 13,40
L140
0,56 mH
0,2 Ohm EUR 11,50
Coils
up to 180 Watt
PA-Trafo
mo-123200
0,12 Ohm EUR 91,00
PA-Trafo
mo-125490
0,19 Ohm EUR 32,68
PA-Trafo
mo-125470
0,16 Ohm EUR 30,71
H140
4,7 mH
0,26 Ohm EUR 31,05
H140
3,3 mH
0,19 Ohm EUR 29,15
H140
2,2 mH
0,14 Ohm EUR 17,30
H140
1,5 mH
0,11 Ohm EUR 15,30
L140
1,00 mH
0,30 Ohm EUR 14,40
L140
0,82 mH
0,26 Ohm EUR 13,40
L140
0,56 mH
0,2 Ohm EUR 11,50
Coils
up to 330 Watt
PA-Trafo
mo-123200
0,12Ohm EUR 91,00
PA-Trafo
mo-125490
0,19Ohm EUR 32,68
PA-Trafo
mo-125470
0,16Ohm EUR 30,71
PA-Trafo
mo-125450
0,14Ohm EUR 27,00
BT140
3,3 mH
0,22 Ohm EUR 67,90
BS140
2,2 mH
0,16 Ohm EUR 32,85
BS140
3,3 mH
0,12 Ohm EUR 30,55
H140
1,0 mH
0,08Ohm EUR 14,40
L200
0,82 mH
0,16 Ohm EUR 33,85
L200
0,56 mH
0,11 Ohm EUR 28,05
Coils
up to 550 Watt
PA-Trafo
mo-123200
0,12Ohm EUR 91,00
T250
10 mH
0,16 Ohm EUR 199,00
T250
6,8 mH
0,12 Ohm EUR 189,00
T250
4,7 mH
0,08 Ohm EUR 175,00
T200
3,3 mH
0,10 Ohm EUR 106,00
BT140
2,2 mH
0,12 Ohm EUR 64,90
BT140
1,5 mH
0,09 Ohm EUR 49,90
L200
1,0 mH
0,18 Ohm EUR 36,75
L200
0,82 mH
0,16 Ohm EUR 33,85
L200
0,56 mH
0,11 Ohm EUR 28,05
Coils
up to 1000 Watt
T250
15 mH
0,17 Ohm EUR 242,00
T250
10 mH
0,16 Ohm EUR 199,00
T250
6,8 mH
0,12 Ohm EUR 189,00
T250
4,7 mH
0,08 Ohm EUR 175,00
T200
3,3 mH
0,10 Ohm EUR 106,00
T200
2,2 mH
0,09 Ohm EUR 90,90
T200
1,5 mH
0,09 Ohm EUR 77,90
L250
1,0 mH
0,12 Ohm EUR 67,90
L250
0,82 mH
0,10 Ohm EUR 62,90
L250
0,56 mH
0,08 Ohm EUR 53,45

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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