Lee
07-16-2002, 06:06 AM
5.14 How do I build my own passive crossovers? [JSC]This section assumes that you have a basic understanding of how to solder, so the actual assembly of the crossover is not discussed. Rather, tips on choosing the proper types of capacitors and inductors are given here.
To obtain low insertion losses, the inductors should have very low resistance, perhaps as low as 0.1 to 0.2 ohms.
Also, be sure to select capacitors with proper voltage ratings. The maximum voltage in the circuit will be less than the square root of the product of the maximum power in the circuit and the nominal impedance of the driver. For example, a 4 ohm woofer being given 100W peak will see a maximum voltage of sqrt(100*4) = sqrt(400) = 20V. Make sure that the capacitors are bipolar, too, since speaker signals are AC signals. If you cannot find bipolar capacitors, you can use two polar capacitors in parallel and in opposite polarity (+ to - and - to +). However, there are some possible problems with this approach: the forward voltage rating will probably not be equal to the reverse voltage rating, and there could be a reverse capacitance as well. Both problems could adversely affect your circuit if you decide to use opposite polarity capacitors in parallel.
To obtain low insertion losses, the inductors should have very low resistance, perhaps as low as 0.1 to 0.2 ohms.
Also, be sure to select capacitors with proper voltage ratings. The maximum voltage in the circuit will be less than the square root of the product of the maximum power in the circuit and the nominal impedance of the driver. For example, a 4 ohm woofer being given 100W peak will see a maximum voltage of sqrt(100*4) = sqrt(400) = 20V. Make sure that the capacitors are bipolar, too, since speaker signals are AC signals. If you cannot find bipolar capacitors, you can use two polar capacitors in parallel and in opposite polarity (+ to - and - to +). However, there are some possible problems with this approach: the forward voltage rating will probably not be equal to the reverse voltage rating, and there could be a reverse capacitance as well. Both problems could adversely affect your circuit if you decide to use opposite polarity capacitors in parallel.