The Art of Synth Soloing - Pitch Programming Potential

July 3, 2013

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.
The Stab

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.

Dynamic Control

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 pitch swoop.

 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 exploring!

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