Crossover Design Chart and Inductance vs. Frequency Calculator(Low-pass)

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Lowpass Filter	To determine the crossover frequency a certain amount of inductance will give you, use the formula: RL/(6.283 x L) = F
Explanation of Terms RL - is the impedance of the load (speaker) you will be using. L - is the inductance value (in Henries) - to convert to Henries divide the value shown on the inductor in mH by one thousand. F - is the crossover frequency you will get.

by frequency
Crossover Frequency (Hertz)	inductance mH (milliHenry)
Crossover Frequency (Hertz)	8 Ohms	4 Ohms	2 Ohms
80	15.92	7.96	3.98
100	12.73	6.37	3.18
120	10.61	5.31	2.65
150	8.49	4.24	2.12
200	6.37	3.18	1.59
280	4.55	2.24	1.14
400	3.18	1.59	0.8
600	2.12	1.06	0.53
800	1.59	0.8	0.4
1000	1.27	0.64	0.32
1200	1.06	0.53	0.27
2000	0.64	0.32	0.16
4000	0.32	0.16	0.08
5000	0.25	0.13	0.06
6000	0.21	0.11	0.05
8000	0.16	0.08	0.04
10000	0.13	0.06	0.03
12000	0.11	0.05	0.03

by inductor
inductance mH (milliHenry)	Crossover Frequency (Hertz) approximate
inductance mH (milliHenry)	8 Ohms	4 Ohms	2 Ohms
0.1	12733	6366	3183
0.2	6366	3183	1592
0.27	4716	2358	1179
0.3	4244	2122	1061
0.33	3858	1929	965
0.4	3183	1592	796
0.5	2547	1273	637
0.6	2122	1061	531
0.7	1819	909	455
0.8	1592	796	398
0.9	1415	707	354
1.0	1273	637	318
1.2	1061	531	265
1.8	707	354	177
2.0	637	318	159
2.2	579	289	145
2.7	472	236	118
3.0	424	212	106
3.3	386	193	96
4.0	318	159	80
4.7	271	135	68
5.0	255	127	64
6.0	212	106	53
7.0	182	91	45
8.0	159	80	40
9.0	141	71	35
10.0	127	64	32
12.0	106	53	27
15.0	85	42	21

Calculate for any Value
To use this calculator, enter the amount of inductance you have available in the first box. Then enter the impedance of the speaker you will be using with this filter in the box below that. Finally, click the "Calculate It" button to see the frequency this filter will be -3 dB.
Inductor = mH RL = Ohms	Answer = Hertz

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