Let’s continue having fun with oscillator pitch programming, which we started last month. Using
an envelope generator to shape some variations in pitch tuning can add
interest to your lead sounds. Actually, we first explored this in the
September 2012 issue, when discussing pitch sweeps of hard-synced
oscillators. However, those techniques won’t work well when the
oscillators aren’t synced, so let’s explore a more general-purpose
concept. Click the thumbnail images to enlarge the screen shots, and scroll to the bottom for audio examples.
| Fig. 1. Modulation envelope depths of all three oscillators set to positive values in Novation V-Station.
||Fig. 2. A similar envelope shape in Rob Papen Blue.
|Fig. 3. Assigning the pitch envelope in the Korg Kronos’ AL-1 synth to swoop up from below.
| Fig. 4. Useful pitch envelope settings in AL-1.
This is the most common and classic technique, and it’s
used not only for leads, but many fast-attack poly synth sounds, brass
emulations, and other more or less crisp textures. The basic idea is to
program a quick swoop up or down into the main pitch, using an envelope
generator. It doesn’t need a complex envelope, just start and end points
with a time or rate between the two.
Let’s look at a possible shape. In Figure 1, the only parameter we’re using is the decay stage of the ADSR envelope. In Figure 2,
we’re using a rate-and-level type of envelope, with attack set somewhat
high, and a semi-fast decay time to a level of zero. Routed to modulate
oscillator pitch, this envelope shape will cause a rapid glide. If the
envelope is set to positive modulation, the pitch will start from a
higher level determined by your modulation depth, and come down to
unison at the speed determined by the decay stage. You’ll want a rather
quick return to unison so it sounds like a “sting” rather than
discernible portamento, so adjust the decay time to taste. It also
sounds fine coming up from below the pitch. To do this, set the envelope
to a negative or inverted modulation.
The amount of pitch modulation is set on the pitch
modulation page/parameter of your synth. Looking again at Figure 1, you
can see that each oscillator has a dedicated “Mod Env” amount knob, and
they’re set to positive positions about two ticks north of “noon.” This
makes the pitch swoop down from above. Increasing that to four ticks
would cause much deeper pitch modulation, and I might speed up the decay
stage of the envelope to compensate. Also, though Figure 1 shows all
oscillators being modulated, in most cases you’ll want to modulate just
one, leaving the others to give your notes a stable tonal center. Figure 3 shows a sweep-from-below setup on a pitch modulation page of the Korg Kronos’ AL-1 virtual analog mode.
With a multi-step level and rate-based envelope, you can
also affect the amount of pitch modulation based on the attack level
(not the time). A low level produces a smaller “sting” no matter how
deep the modulation is. I suggest a relatively high attack level as
shown in Figure 4—you’ll want some range for some of the concepts we’ll be covering in a moment.
Fig. 5. Velocity is modulating the depth of the envelope’s effect on pitch on Spectrasonics Omnisphere.
| Fig. 6. Velocity set to increase (slow down) the pitch envelope attack—play harder to make the effect more pronounced.
With the above basics you can add a nice pitch stab to
your attack. But I’m all about control and expression, so let’s add
something more to this recipe. First, let’s make the amount of pitch
modulation dynamic; I like using velocity to bring in the effect. There
are a number of ways to do this.
Modulate the modulation. If your pitch modulation amount can itself
be modulated, we can do it as follows. On your pitch modulation page,
or in your mod matrix, set the source to be your envelope, with a pitch
mod amount of zero. Then set velocity (use exponential velocity if your
synth has that option) to modulate the envelope amount/intensity. With a
medium velocity bringing in the envelope depth, you should be able to
play softly with no pitch stab. As you play harder, it introduces the
envelope pitch modulation and increases the stab. Figure 5 shows a setup that achieves this in Omnisphere’s mod matrix.
Modulate the envelope. In Figure 6, we
modulate the envelope attack time. First, set your envelope to modulate
pitch with depth to your liking. Then go to the envelope
page/parameters, and (in the case of my AL-1 example) lower the attack
time to zero. Now go to the time modulation parameter, set its
modulation source (referred to as AMS on Korg synths) to exponential
velocity, and modulate the attack time with a positive value. When you
play softly, the attack time is zero (instant) and you hear no effect.
As you play harder, the attack time increases and you hear more of the
| Fig. 7. Using a knob instead of velocity to do the same
|| Fig. 8. The same knob reducing (speeding up) attack time as it increases pitch modulation depth.
Dial the Depth
For more control still, I like to dial the effect in and
out at various depths. For this, I’m going to undo the previous velocity
assignment and use a bipolar knob (noon equals zero, with negative
values to the left and positive to the right) to modulate the envelope
depth instead. Here, give yourself a lot of range. On your synth’s pitch
modulation page, set the intensity of the knob to a high value. In the
Kronos’ AL-1, I use +18, as in Figure 7. This produces a tasty
amount during the beginning of the knob travel but goes over the top as I
turn the knob further clockwise.
Here’s a final trick: Set the same knob also to
modulate the attack time. Using a negative value, you can speed up the
attack time (lower the value) with the same knob twist that increases
the depth. (See Figure 8.) These two changes offset one another,
which has the effect of tapering the knob response—it’s more dramatic in
the beginning but gets subtler as you keep turning clockwise. Happy