3 WAY CROSSOVER EXAMPLE
Note, this sample crossover makes use of many of the calculators found on the menu on the left. You should also review the Crossover FAQ for help with this example.
For this example, I picked 3 ScanSpeak drivers for a 3-way speaker (the same 3 used on the Speaker Box Example. Note: This example old and the characteristics of these drivers have since changed. These drivers were not picked because of how well the worked together, but rather because they have problems that can be solved with the proper circuit. The drivers I chose were:
Driver | Model | Frequency Range | Imped | Sensitivity | Fs | Response Curve |
Tweeter | D2008/8512 | 2k-30k Hz | 8 ohms | 90 db SPL | 1000Hz | Chart |
Mid | 13M/8636 | 200-4k Hz | 8 ohms | 88 db SPL | | Chart |
Woofer | 18W/8543 | 35-3.2k Hz | 8 ohms | 89 db SPL | | Chart |
All of the drivers are 8 ohms. There are no differences in output caused by different impedances with the drivers. The tweeter has 2db sensitivity over the mid, and the woofer has 1db sensitivity over the mid. Resistors will be used to balance out the sensitivity/load problems. A l-pad circuit will be used to lower the tweeter output by 1db and the woofer output by 2db.
The Fs ( free air resonance ) of the tweeter is at 1000Hz. This is the frequency at which the tweeter will resonate, and produce a large positive spike in the frequency response. A series-notch filter will be used to remove this spike.
You want to pick crossover points between the two drivers. Remember that it is a base 2 logarithmic scale. For the mid/woofer crossover there are 4 octaves between 200-3.2k Hz, 200-400-800-1600-3200. 800 Hz is the middle frequency, with 2 octaves flat in either direction. For the tweeter/mid crossover, there are only 1 octaves, 2000-4000. 3k Hz is the crossover point with 1/2 octave stable in either direction. These two drivers have little overlap, and normally would not be used together.