# I need expert passive crossover component selection answers.



## Alias essSQuee (Dec 22, 2009)

Hey,

I'm going to tinker around with some passive crossover designs at some point in the future and will be assembling an array of passive components and boards as well as a soldering kit.

I found this passive filter table with specific parts and their resulting crossover frequency corresponding to the ohm load of the speaker:

Speaker Crossover Chart and Capacitance vs. Frequency Calculator(High-pass)

by frequency
Crossover Frequency (Hertz)	Capacitance uF (microFarad)
8 Ohms	4 Ohms	2 Ohms
80	248.44	496.88	993.75
100	198.75	397.50	795.00
120	165.63	331.25	662.50
150	132.50	265.00	530.00
200	99.38	198.75	397.50
280	70.98	141.96	283.93
400	49.69	99.38	198.75
600	33.13	66.25	132.50
800	24.84	49.69	99.38
1000	19.88	39.75	79.50
1200	16.56	33.13	66.25
2000	9.94	19.88	39.75
4000	4.97	9.94	19.88
5000	3.98	7.95	15.90
6000	3.31	6.63	13.25
8000	2.48	4.97	9.94
10000	1.99	3.98	7.95
12000	1.66	3.31	6.63


by capacitor
Capacitance uF (microFarad)	Crossover Frequency (Hertz) approximate
8 Ohms	4 Ohms	2 Ohms
2.2	9034	18068	36136
3.3	6023	12045	24091
4.7	4229	8457	16915
6.8	2923	5846	11691
10.0	1988	3975	7950
22	903	1807	3614
50	398	795	1590
100	199	398	795
200	99	199	398
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Okay, the issue that crept into my head. Ohm load changes with speakers according to frequency. When selecting a capacitor for a specific frequency according to this chart, do I select the part based on the stated ohm load of the speaker, or do I select the part based on the ohm load shown on an impedence curve?










The point is, "if" I decide to use a crossover frequency outside of the driver's stated ohm load, would I be targeting a different capacitor than the stated total ohm load of the speaker?

This is a question that has been bugging me.


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## Luke352 (Jul 24, 2006)

I suggest you read this... Passive Crossover Network Design and then come back with any questions you may have. He spends alot of time going over the problem you are encountering.


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