Electronic Crossover

Introduction

In multi-way loudspeaker systems, it is usual practice to divide the sound into bass, middle and treble, then feed each through its own driver. This means that one part of the system is designed to handle bass only, another midrange only and another treble only.

The advantage of using digital signal processing (DSP) over discrete electronic components is one of flexibility; the DSP system is much easier to adjust.

C Code Implementation

The 2-way electronic crossover produces bass and treble outputs using a 51-point Finite Impulse Response (FIR) filter. Unlike an Infinite Impulse Response (IIR) filter, this type of filter is stable and has a linear phase response.

In order to sample at 24 kHz, the treble and bass filters have been combined together because separate bass and treble filters would be too slow.

Using the Electronic Crossover

The frequency at which bass and treble are divided is adjustable using the user switches on the TMS320C6711 DSK. The optimum crossover frequency does depend upon the loudspeakers being used and the type of music being played.

The range of crossover frequencies can also be changed by using different filter values. For the full range of crossover frequencies, see the header file lowpass.h

Using the Sweep Generator

The electronic crossover can be used with an input from a CD player. Alternately, with a small change to code, the sweep generator instead. This generates sine waveforms right across the audio band from 60 Hz to 12 kHz.

Additional Equipment Required

Multimedia speakers

CD player with connecting cable

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