Sound Design Tips and Tricks – Know Your Oscillators
It all begins with the oscillators... If those don’t sound great, no amount of filtering or effects will ever really be able to fix that. Venom addresses this issue in a clever way, by playing back samples of classic analog waveforms as well as modern digital sources. Sampling allows you to go directly to the oscillators of the best synthesizers and drum machines ever made and easily capture every spectral nuance of their waveforms.
As opposed to mathematical modeling, sampling duplicates the exact waveforms using very little horsepower in the DSP. However, the sample is like a snapshot, and the changes that take place over long periods of time, such as analog frequency drift, are not accurately reproduced. But with the savings in processor power, Venom allows you to reintroduce this behavior (and much more) through a comprehensive set of modulation parameters and sound shaping tools.
Tip 1 – Recreating analog oscillator behavior
The first thing that comes to mind is how the frequency of an analog oscillator drifts over time. It slowly meanders in a seemingly random fashion as the circuit reacts to small variations in temperature and other factors. To quickly add some of this behavior to a Venom sound, turn up the Drift parameter using the oscillator section of the Vyzex editor.
Drift will add small random variations to the base frequency of each oscillator each time you press a key. It does introduce some nice phasing as the detuned oscillators beat against each other, but Drift doesn’t actually go so far as to continue moving the frequencies around over time. For that, we’ll need to set up some LFO modulations.
I like to use LFO 2 set to the “Linear Sample and Hold” shape in order to introduce a smooth random modulation as the note is held.
And since you can address each oscillator’s pitch independently, you can really enhance the analog vibe by setting different modulation amounts for each of them. This will cause the frequencies to “fan out” and the oscillators will beat against each other at different rates, but the overall pitch movement will be in the same direction if the modulation routes are all set to the same positive (or negative) polarity.
To add the finishing touches to our analog frequency drift, I use LFO 3 to modulate the rate of LFO 2. Although the level values of the Linear Sample and Hold are random, the clock timing isn’t, so it’s a good idea to make this additional modulation route in order to avoid hearing pitch variances occurring at regular intervals.
I bet you thought we were finished at this point, but there’s one more important component to recreating analog behavior in the oscillators, and that’s phase. Analog oscillators are always oscillating behind the scenes, and we hear them only when the filter and amplifier are opened (usually by an envelope). This means that the audible starting phase of the waveform is more or less random since you can’t really control the precise timing of when you play a note and reveal the waveform cycle.
Samples on the other hand, tend to always start at the same spot – the beginning. So, in order to simulate phase variance, Venom provides an oscillator Start Mod parameter, which chooses a random spot in the length of the waveform sample to begin playback. As with the Drift parameter, Start Mod applies the effect randomly, and in different amounts, across all three Venom oscillators whenever a voice sounds.
Okay, so let’s take a listen to what we just did. Listen to the audio file below to hear a three saw-tooth oscillator sound before and after the application of analog simulation.
Tip 2 – Using the Waveshaper to generate PWM
There are some other tricks to bringing more traditional analog behavior to Venom’s waveforms. Pulse Width Modulation is one of those essentials that you wouldn’t necessarily expect from a sample, but Venom provides an interesting and ultimately more versatile way of accessing that classic sound. The key is in the Waveshape parameter on Oscillator 1.
Venom’s Waveshaper takes any waveform that you feed it and turns it into a rectangular wave of varying pulse width patterns. The Waveshape threshold parameter determines the overall shape. Any part of the wave that falls above the threshold gets set to full positive, while anything below is set to full negative.
Since Venom’s waveform samples have a fixed pulse width, we use them instead as a reference plot for the Waveshaper algorithm. On Venom, to make the classic Pulse Width Modulation sound, you actually have to start with a saw wave rather than a square, and as you modulate the threshold up and down, the positive going pulse width becomes thinner and thicker respectively.
Listen to the audio file below to hear Pulse Width Modulation generated by the Waveshaper as applied to the MG Saw waveform.
Because Venom achieves PWM through a waveshaper algorithm, that function can be applied to every waveform in the oscillator, not just to the square wave like on most analog synths. Some of the more complex Venom waveforms have multiple peaks per cycle at varying amplitudes, so the resulting PWM can even go to 0% on some peaks while not on others. This can make for some very interesting and gritty textures.
Tip 3 – Unusual uses for drum sounds
Since Venom’s drum samples appear as one-shot waveforms in the oscillators, you can apply algorithmic functions such as the waveshaper to those as well. And changing the threshold takes your kit from a nice rectified distortion sound to complete and utter oblivion... It’s a great effect.
But what I really love is using drums as the source waveform for Sync sounds, which is something you don’t find on a lot of synths outside of the modular world.
Oscillator Sync is generated by resetting the phase of the slave oscillator each time the master oscillator completes a cycle. That way, the slave oscillator takes on the fundamental frequency of the master oscillator while generating new harmonics. By nature of the algorithm, Sync is most interesting when the slave oscillator is set to a higher fundamental frequency than the master, and gets even better when its frequency is being constantly modulated. This creates a shifting set of harmonics over time.
However with a complex master waveform like an analog tom (for example), oscillator Sync causes the slave oscillator to reset many times during the initial attack transient. Then it follows the fundamental frequency in the body of the tom sound as it falls, and finally stops resetting when the drum sample fades out. You can really hear how the sound changes over time if you tune the drum way down. In fact, the sound “Fatality” (A-032 in the preset banks) does exactly that.
Listen to the sound file below to hear “Fatality” show off the concept of using a drum sound as an oscillator Sync source.
Tip 4 – Using Oscillators 2 and 3 as LFOs
Another interesting use for a drum sound in the oscillator is as a one-shot complex LFO waveform. Venom already provides 4 LFOs, but you can add two more by tuning oscillators 2 and 3 down to sub audio rates and applying them as Ring Mod and FM respectively. The FM route becomes a pitch LFO and Ring Mod becomes amplitude modulation.
Of course you can use the “normal” waveforms as well. Just tune the oscillators down all the way using the Coarse tuning parameter and then force them down even further using Envelope 3 routed negatively to the individual oscillator pitches. This allows you to use any oscillator waveform in Venom’s arsenal as an unconventional and distinctive LFO shape.
Listen to the sound file below to hear an example of the oscillators being used as LFOs. Note that none of the 4 main LFOs were used, and that the voice fades out because it follows the envelope of the drum sound used for amplitude modulation.
Tip 5 – Frequency modulation of Noise
In the analog world, it’s impossible to modulate the frequency of noise because it has no frequency. But in Venom, since the noise is a sample in the oscillator, you can vary the sample rate and change its “pitch/formant” characteristics. Pitching White Noise down starts sounding like Brown Noise, while pitching it up edges into Violet Noise.
This is useful not just for changing the audible timbre of the noise, but also for changing the quality of the result when using noise as a pitch or amplitude modulation source. Normally if a synth gives you a choice of noise color, it’s a set-and-forget parameter, but in Venom you can continuously modulate the White Noise “pitch”, both positively and negatively for dynamic “color” variation.
Listen to the sound file below to hear noise used as an FM source, and how varying the sample rate changes the modulation texture.
Venom’s oscillators were designed to give you the best of both worlds. They can sound alive and analog or precise and digital depending on how you choose to use them. The tips listed here barely scratch the surface of all the sonic possibilities in Venom’s deep synthesis engine. Hopefully you’ll be inspired to explore further on your own, and I look forward to hearing the cool new sounds that you discover.
If you’d like to take a closer look at the Single Programs used in the sound examples, they’re available for download at VenomSynth.com:
To learn more about the Venom synth watch the intro video, listen to audio samples, and check out the buzz.
PS: Continue on to Part 4 - More Tools for Sculpting Your Sound.
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