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Step 9Wiring and Crossover
The crossover, which routes the proper frequencies to the proper drivers, for this project will be very simple. Crossover design is a very complex and intricate matter when done properly, but this specific design is about deep bass extension and efficiency, not hi-fi. That said, it doesn't have to be a complete mess. Below is the schematic for 1 channel of the stereo pair which is 4 woofers, 4 midranges, and 2 tweeters. The circuits below are wired together in parallel and duplicated for the other channel. The component values are based on the impedances and relative efficiencies of these specific drivers.
The woofers are 4 ohms each with an 87dB efficiency rating. The four woofers in the series-parallel configuration raises the efficiency to 93dB. At 4 ohms total, that means a 96dB sensitivity rating (@2.83V input).
The midranges are 8 ohms each with a 90dB efficiency rating. The four midranges in the series-parallel configuration raises the system efficiency to 96dB. At 8 ohms total, that means a 96dB sensitivity rating (@2.83V input) - equal to the woofers.
The tweeters are piezoelectric units which do not behave as normal resistive loads and as such the 10 ohm resistor on them was chosen by ear.
If using different drivers, try to find woofers and midranges that are similar in sensitivity, and then a single resistor can be used to attenuate the tweeters, which are usually more sensitive than the other divers. The value of this resistor can be determined by listening - the lower the value, the higher the attenuation.
- Edited 2/22/2010 - After listening to this setup for a while, I have made some pretty serious modifications to the crossover. These modifications will only apply properly if using the exact drivers that I have used, but it may be worth a try even with slightly different drivers.
Woofer Circuit: change 0.7mH inductor to 1.5mH inductor
Midrange Circuit: remove 0.4mH inductor, change 16uF capacitor to 12uF, insert 3.0mH inductor in parallel with midrange assembly
Tweeter Circuit: remove 10 ohm resistor, change 3.3uF capacitor to 2.2uF
The woofers are 4 ohms each with an 87dB efficiency rating. The four woofers in the series-parallel configuration raises the efficiency to 93dB. At 4 ohms total, that means a 96dB sensitivity rating (@2.83V input).
The midranges are 8 ohms each with a 90dB efficiency rating. The four midranges in the series-parallel configuration raises the system efficiency to 96dB. At 8 ohms total, that means a 96dB sensitivity rating (@2.83V input) - equal to the woofers.
The tweeters are piezoelectric units which do not behave as normal resistive loads and as such the 10 ohm resistor on them was chosen by ear.
If using different drivers, try to find woofers and midranges that are similar in sensitivity, and then a single resistor can be used to attenuate the tweeters, which are usually more sensitive than the other divers. The value of this resistor can be determined by listening - the lower the value, the higher the attenuation.
- Edited 2/22/2010 - After listening to this setup for a while, I have made some pretty serious modifications to the crossover. These modifications will only apply properly if using the exact drivers that I have used, but it may be worth a try even with slightly different drivers.
Woofer Circuit: change 0.7mH inductor to 1.5mH inductor
Midrange Circuit: remove 0.4mH inductor, change 16uF capacitor to 12uF, insert 3.0mH inductor in parallel with midrange assembly
Tweeter Circuit: remove 10 ohm resistor, change 3.3uF capacitor to 2.2uF
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