Telex ISP-100 manual Four-Way Crossovers, 8Four-way crossover implementation

8-17

Four-Way Crossovers

Figure 8-8Four-way crossover implementation.

In the ISP-100, 4-way crossovers are implemented as shown in Figure 8-8.

This parallel structure was selected over the more common binary- tree structure for its suitability to the distribution of filters among multiple DSPs. The parallel structure is also capable of perfect implementation of Linkwitz-Riley crossovers, for which the ISP-100 has been optimized. The filters marked optional in Figure 8-8 will be explained in the Linkwitz-Riley Crossover section.

The lowpass filters LPx (except for the optional LP2) and the highpass filters HPx (except for the optional HP2) may each be independently configured as:

Bessel 6 dB/octave (1st-order)

Bessel 12 dB/octave (2nd-order)

Bessel 18 dB/octave (3rd-order)

Bessel 24 dB/octave (4th-order)

Butterworth 6 dB/octave (1st-order)

Butterworth 12 dB/octave (2nd-order)

Butterworth 18 dB/octave (3rd-order)

Butterworth 24 dB/octave (4th-order)

Linkwitz-Riley (Butterworth-Squared) 12 dB/octave (2nd-order) Linkwitz-Riley (Butterworth-Squared) 24 dB/octave (4th-order)

In addition, the cutoff frequency, attenuation, and polarity in the low band, the low-mid band, the mid-high band, and the high band may be independently adjusted, and all of the filters in any band may be bypassed entirely.

The cutoff frequency in each filter is continuously variable from 20 Hz to 20 kHz.

Processing Components - Crossover