The AES Electronic Car Crossover

The pre-amplifier / switcher has a built in cross-over ciruit for the
purpose of bi-amplifying the system. Many members in the group express a
great deal of interest in using this cross-over circuit in a car where
subwoofers are very common. The basic cross-over circuit required little in
the way of changes to accomidate use in a car. What was needed for use in a
car was a dual-polarity, regulated power supply to allow use of the circuit
unmodified.

The crossover is 4th order (24 dB/octave) Linkwitz Riley. The frequency is
adjustable by changing resistor networks to any frequency in the 40 - 200
Hz range. 10 dB of output gain is provided on the bass channel along with a
volume control to set the bass gain.

Disclaimer

None of the circuit diagrams below come with any sort of warranty, may not
meet any legal requirements for safety or UL listing, nor are they even
guaranteed to work. They are provided for educational purposes ONLY. You
use them at your own risk.

Schematics

Car 9 Volt Power Supply

     The initial version of this supply was tested and found to generate
     noise on the audio lines at a frequency of about 8 khz. It has been
     discarded for an different circuit.

Base Cross-over Circuits (Low- and High-pass)

     There are superior circuits that reduce the component count in half
     for this x-over. However, they do not allow asymetrical cross-over
     points.

Full Cross-over Circuitry

     For the car application, the input buffer is required (discard the
     "pre-amp direct" connection). The high-pass potentiometer and buffer
     are unnecessary since most car amplifiers have built-in gain
     adjustment. The bass-gain potentiometer may even be eliminated if the
     subwoofer amplifier has its own gain control.

