© 2003 TDM Audio, Inc. Electronic Crossover Owner’s Manual Page 8
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Figure 4 - 24 dB per Octave Filter Curve
To make a 2-way crossover, we feed the same signal into a high-pass filter and a low-pass filter with the same cutoff frequency. This is called the crossover frequency. The output of the high-pass filter is the high output of the crossover. The output of the low-pass filter is the low output of the crossover. The crossover frequency knob simultaneously adjusts the cutoff frequencies of both filters to vary the crossover frequency. Because the cutoff frequency of a filter is the point at which the output signal is 6 dB below the input signal (which means that it has half of the amplitude of the input signal), the crossover frequency is the frequency where half of the signal goes to the low speaker and half goes to the high speaker. Below the crossover frequency, progressively more signal is sent to the low speaker. Above the crossover frequency, progressively more signal is sent to the high speaker. Thus, there is a smooth transition between the low and high speakers. This is why we call it a crossover. To illustrate, Figure 5 shows the frequency response curves of both filters in a 24 dB per octave 2-way crossover at 1000 Hz.-140
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