A world of possibilities opens up when you tune two or
more synth oscillators in various ways, relative to one another. Let’s
Here’s a classic sound—the warm beating of oscillators
drifting ever so slightly (or not so slightly) against each other. A
common approach is to use the same waveforms and have one oscillator
tuned to exact pitch, and then set the other oscillator slightly sharp
or flat, usually by only a few cents. A better approach is to spread
both oscillators a bit, setting one slightly flat and the other slightly
sharp. This doesn’t pull your ear in a specifically sharp or flat
direction. It’s also the better approach when you want wider or more
Power tip: Some synths (like the AL-1 engine in the Korg
OASYS and Kronos, or Native Instruments Absynth) have advanced means to
control tuning via offsets, ratios, or other methods. These differ from
conventional tuning or fine-tuning parameters in that they can impart a
constant beat frequency (the modulation you hear when two notes—like
synth oscillators or guitar strings—are almost but not quite identical
in pitch) across the whole keyboard, rather than the usual “smeared
tuning” sound you get from detuning.
If you don’t want to “spend” two oscillators to achieve
this sound (or your synth only has one oscillator) look to the waveform
choices offered and see if there’s a variant that is already detuned.
Roland was the first to offer that in their JP-8000 hardware virtual
analog synth, with its “super saw” that used DSP to stack up seven
detuned sawtooth waves while only using one voice of one oscillator.
Many other synths now offer this type of wave, calling it “HyperSaw” or
some other telltale variant. Another approach is using the Unison
parameter in your synth—many have this and it lets you set both the
number of voices used and their detuning amount. Just note that if you
want to use another oscillator for a different waveform or effect (like
sync, perhaps), Unison will also affect that.
If you want to recreate the slight drift that older analog
synths had, you should use a different approach. I’m not talking about
overall pitch drift (which may be available as its own parameter in your
synth and called something like “analog drift” or “humanize”). I’m
talking about the variation of the interval between the two oscillators.
This is subtler, as it’s the sound of oscillators trying to stay
in tune but drifting in and out slightly. Using tuning offsets like the
above means that the given oscillator is always slightly sharp (or
flat), and that’s not the same. What to do? Use an LFO, set to either a
triangle or sine wave, to modulate the pitch of one of the oscillators.
The rate should be slow and the depth set to taste. This produces a
variation in pitch that includes returning to perfect unison in between
sweeping slightly sharp and slightly flat.
One trick I like here is to set the modulation depth to a
known interval (whole step, fifth, octave) for reference while I choose
the rate amount, as it’s easier for the ear to detect the rate of a
sweeping interval than very subtle pitch variations. Once I get a rate I
like, I then reduce the depth a suitable amount. If you’d rather not
have such a repeating, periodic change in pitch, see if your synth
offers a random waveform for the LFO. U-he’s free soft synth Podolski
(shown) is one example. Some synths offer random shapes, some producing
more stepped changes, others yielding smoother but still changing
Tuning oscillators in pure intervals is another classic
sound, and there are plenty of permutations to explore. The most common
choice is setting a second oscillator an octave above or below the
first. Both synth leads and synth basses do this all the time. Be sure
to try mixing the oscillator volumes in various ways—they don’t always
have to be the same level. Some synths have a sub-oscillator fixed at an
octave (or two) down. Great—that frees up your second oscillator for
some detuned doubling, or to produce yet another octave, so you could
get 16', 8', and 4' “footages” in the same patch.
Tuning a second oscillator a fourth (+5 semitones) or
fifth (+7 semitones) above the first produces a Chick Corea-style fusion
lead sound. If you reduce the level of the detuned oscillator it
becomes less dominant, acting more like a harmonic of your main sound
and less like an obvious interval. I especially like to raise the tuned
oscillator an additional octave (+19 or +21 semitones, i.e., one
octave plus a fourth or fifth) and just blend it in a bit. Also be sure
to try different waveforms for the tuned interval. Triangle, sine, or
wide pulse waves can help soften the harmonic.
I’ve been hearing oscillators tuned in minor thirds (+3
semitones) and major thirds (+4 semitones) in electronic dance music.
This is less “inside” sounding and works better for melodic parts that
aren’t necessarily about the old-school “let ’er rip” type of soloing.
Don’t be afraid to explore these! Likewise, tuning three oscillators to
produce a minor or major triad can sound like a sampled chord hit, and
may be just the effect your track needs.