For best results, even with mono signals, use both inputs on the Z-DSP and the stereo
out. A short Stackcable can be used to connect the left and right inputs to a mono signal.
Chorus is one of the most essential eects for synthesizers and the chorus unit on many
classic poly synths created much of their sonic signatures. This card for the Z-DSP oers 8
dierent algorithms inspired by some of the most classic eects in the genre.
Chorus eects use one or more delay lines which are modulated to produce a ‘doubling’ of
the sound as if more voices are present. Programs vary from two to six delay line ‘taps’ or
voices. Generally, the more voices the thicker and more complex the sound.
The delay times of these programs tend to be in the 18-24 millisecond range which is com-
mon to most of the high end studio devices. Analog pedals are more in the anger < 10ms
range in order to use cheaper BBD parts, but there is also a Dual Flanger program with
shorter times on the card.
LFO modulation provides a way to not only break up the comb ltering of a static delay,
but also creates a sense of movement in stereo. Several of the programs use one or more
methods like multiple LFOs, quadrature LFO, random walk and phasing to produce even
more movement in the stereo eld.
LFOs have both Rate and Depth controls: Rate is simply the speed of the LFO, and depth is
how wide the LFO sweeps through the delay line. Most of the Programs on the card have
Rates from several seconds to several times a second (0.1 Hz to 6+ Hz). Depth can vary the
delay line position from less than 1ms to the entire delay range of 20ms or more. As the
LFO sweeps through the delay line the sound changes pitch producing a ‘detune’ eect.
Detuning is really what makes the ‘choral’ element in a Chorus eect.
Setting a slow Rate and higher Depth makes the pitch change subtler and can be very ef-
fective on pad and other ambient sound sources. Increasing the Rate will introduce a more
pronounced vibrato eect and extreme settings of Rate and Depth can sound underwater.
Adding external Feedback can make the Chorus sound more intense and high levels of fee-
dback can add a small room ambience. The Dual Flanger program has an internal feedback
for the classic Flanger swoosh.
Chorus eects can sound quite subtle compared to many other types of eect, and in
some cases the eect is only noticed when it is switched o!.
