3-Way Crossover Designer / Calculator Help
Use the 3-Way Crossover Calculator.
An APC (All-Pass Crossover) circuit is designed to create a flat voltage output. This 3-Way Crossover Designer is more than just two combined 2-Way Crossovers. The parameters are slightly different to account for 3 drivers. The parameters can only be calculated when the 2 crossover points are 3.0 or 3.4 octaves apart.
Note: For this calculator, bandpass refers to the midrange driver where both the low pass and high pass filters are applied. For more information on crossovers, see the 2-Way Crossover Help, the Crossover Tutorial & the Crossover FAQ.
To use this calculator, enter the resistance of each driver, one of the crossover points, the frequency spread, and the crossover type. The second crossover frequency will be automatically calculated. The bandpass gain (the db gain for the midrange driver) is also automatically calculated. This gain will vary with the crossover spread and type.
A 2+ bandpass gain is significant, and it will make the mids sound louder than the rest of the speaker system. If the sensitivity of the midrange speaker is 2db lower than the other drivers, then this will actually solve a problem for you. Otherwise, you may want to use a Parallel Notch Filter to lower the output of the midrange driver.
Note that some crossovers can produce phase shift problems. A second order crossover will shift the phase of each speaker 90 degrees, so that both speakers are 180 degrees out of phase. This means that at the crossover frequency, the two drivers will be moving in opposite directions at the same time. They will cancel each other out and produce a 30db dip in the frequency response at the crossover point. Reversing polarity of one (but not both) of the speakers will limit this dip to +- 3db. Each 3-way APC crossover is labeled as reverse or normal polarity for the bandpass speaker. For the reverse polarity crossover, the + and - connections on the midrange (bandpass) speaker are reversed. The reversing in polarity prevents phase shift problems.