User's Manual

5.7. CROSS
The CROSS fader in VCO-1 controls how much VCO-2 will cross-modulate VCO-1. This
may be used for frequency modulation-type effects, noise modulation, or low-frequency
modulation.
5.7.1. Frequency Modulation
Frequency modulation is a dramatic synthesizer technique that adds multiple overtones
to the sound by modulating VCO-1 with VCO-2. Technically, it generates sum, difference,
and multiple frequencies between the two generators. Unlike most musical sounds, this
modulation can produce overtones that are not harmonic (that is, not multiples of the
fundamental frequency).
When VCO-2's range switch is in the NORM position and its WAVE is set to anything besides
Noise, the amount of frequency modulation is controlled from 0% to 100% by clicking on
the CROSS fader and dragging up or down. The resulting sound will be more radical as
the frequency of VCO-2 differs more from the frequency of VCO-1. Low single-digit settings
of the Fine control of VCO-2 result in tremolo/vibrato effects; higher settings produce
nonharmonic tones. When CROSS is at maximum, the modulating frequencies overwhelm
the fundamental of the oscillator. The result is more noiselike than tonal.
When VCO-2's RANGE is set to 5 (a fourth interval) or 7 (a fifth interval), the result is
something like ring modulation with harmonics that are related to the fundamental
frequency, so the resulting sound is a little more musical.

♪: When CROSS is being used, modulating the frequency of VCO-2 with the BEND wheel or ENV-1 (in
the VCO MODULATOR section) leads to some dramatic effects. CROSS level is listed as a destination in
the Modulations section of the Advanced Panel as "VCO Cross Mod".
5.7.2. Noise modulation
Turn the WAVE knob of VCO-2 to the Noise position to turn on noise modulation.
• When VCO-2 is in the NORM (white noise) range it adds "fuzz" to the tone; it also
shifts VCO-1's frequency up, so the keyboard is essentially transposed depending
on how high the CROSS level is.
• When VCO-2 is in the LOW (pink noise) range, "static" dominates the sound.
5.7.3. Using VCO-2 as an LFO
The other application of CROSS is when VCO-2 is in the LOW setting and the WAVE is
set to Sine, Triangle, or Rectangle. In the LOW range, VCO-2 becomes a fixed-frequency
oscillator; it doesn't track the keyboard notes. In the 16' to 8' range with a low CROSS setting,
it produces a typical vibrato in VCO-1. At higher frequencies, it becomes a fixed-frequency
ring modulation.
That's what the VCOs can do in terms of generating sound. Now we move on to shaping this
sound dynamically through the VCF and VCA.
Arturia - User Manual Jup-8 V4 - VCOs 38