In previous columns, we’ve covered using LFOs for
everything from dubstep “wubs” to Dutch house sirens. So if you’ve been
following along at home, you should have a solid grasp of the essentials
of tempo-synced LFOs.
This month, we're going further down the rabbit hole and
exploring the possibilities of using multiple synced LFOs to create
hyper-rhythmic effects that can make even a basic synth patch do groovy
tricks that would be hard to replicate without resorting to
time-consuming automation tactics.
Application 1: Filters
In dubstep, it’s incredibly common to use a sine or
triangle LFO—applied to filter cutoff on a bass patch—to create that
classic (some might say hackneyed) wub-wub bombast. Things get
way more interesting when you apply two or more different LFOs to the
same filter cutoff destination, especially if you use different
note-value rates and waveforms. Here I used Reason’s Thor to apply dual
LFOs to its Ladder filter—one with a downward sawtooth and the other
with a sine wave—then changed the tempo of the sine wave LFO as the
Application 2: Pitch
Using the same technique described above, I applied the
two LFOs to the pitch of a single oscillator, and then varied the tempo
of the sine wave again. Note: With pitch modulation, a little goes a
long way, so I throttled back on the LFO amounts for each.
Application 3: Advanced Techniques
Once you get the hang of working with multiple LFOs, it’s
time to experiment in earnest. Sticking with Thor, I created a
dual-oscillator patch that relies on hard sync on oscillator 2 to create
harmonic sweeps. From there, I added a sawtooth to the amplifier gain
to create a retriggering effect, then played with the rate of the LFO on
oscillator 2’s pitch, thus syncopating the harmonic rhythms.