
If you completed the previous lesson, Subtractive Basics I, you should be familiar with the purpose and function of the 5 basic tools of subtractive (and most other!) synthesis: oscillator, filter, and amp to make and sculpt the sound; envelopes and LFOs to control those other components. Hopefully you completed the exercises at the end of the lesson and feel comfortable with the basic functions of these components and how they work together. The good news is much of this lesson is just going to be more of the same!
Last time, we posited something like a minimum viable synthesizer – one oscillator, one filter, one amp, with one envelope and one LFO to control it all! While there are real-world synths that are nearly that simple, most synths offer a bit more. A more common configuration would be two oscillators, one filter, one amp, two or three envelopes, one or two LFOs and a few support elements such as a mixer, sub oscillator and noise source. That configuration accounts for something like 60% or more of all subtractive-style synths ever made!
More Control
Doubling (or tripling) the number of each component we’ve previously covered allows for added depth and complexity in your patches. Each LFO or envelope allows you an individual degree of control over another parameter or variable; additional oscillators, filters and amps, along with additional tools like noise, allow for more timbrally complex and nuanced sounds. Put simply, more envelopes and LFOs means more control over your sound.
More Oscillators
Most synths offer at least two oscillators, with three being fairly common (the all-time classic Minimoog had 3, tho you had to use one of them as an LFO if you needed an LFO) and larger numbers rare but not unheard of. These oscillators might be identical, or they may offer slight variations – for example, they might offer different waveshapes, or one might have more options like sync and PWM (pulse width modulation) than the other.
A second oscillator lets you stack waveforms by choosing different waveshapes on each, allowing you to more precisely sculpt the harmonic content of your patch. It also allows you to detune the two oscillators a few cents to introduce some movement and “fatness” to the sound, producing the impression of constant, shifting movement and a sense of taking up more “space” as the oscillators “beat” against each other. Finally, on many synths, an audio oscillator can be used to modulate another audio oscillator, in techniques such as FM and ring modulation, which add additional harmonics to the sound.
More Filters
More often than not, synths offer just a single filter, tho that filter may well offer multiple modes. The four basic filter modes are lowpass (cuts off the highest frequencies), highpass (cuts off the lowest frequencies), bandpass (cuts out high and lows, leaving just a center band of frequencies) and notch (cuts a single band of frequencies). Less common, but far from unusual, some synths offer multiple filters, sometimes offering options to run the filters either in serial configuration (one filter passes signal to the next) or parallel (different signals can be routed to different filters).
We’ll get deep into the different use cases for various filter modes and configurations in a future lesson, but at a high level, you’ll be choosing modes/configurations based on what you wish to remove from (and emphasize in!) your sound.
More Amps
The number of amp stages varies widely across synth designs. It’s not unusual to have just a single amp stage with a hardwired envelope, for example, but some synths, especially digital synths, allow you to control the amplitude at multiple points (eg at the oscillator level, pre and post filter, etc). Single amps are simpler to understand and still cover a huge variety of possible sounds. Multiple amps (with each under control of its own envelope and possibly LFO) offer the possibility for certain elements to come in and out independently – for example, you might want a short blast of one oscillator at the beginning of a sound to emphasize the attack, or a secondary tone that comes in late on a held note to add variance to sustained notes and drones.
Additional Components & Features
Noise
Noise generators are such a common component they are nearly ubiquitous. Noise can be added to sounds to add a bit of grit, an unpredictable element and even a bit of “realism.” Noise can also be used as a modulator in various ways – most notably as the data source for a sample and hold setup, in which the noise is “sampled” on demand (usually via a trigger condition) to derive a value that is then used as a modulator. Noise is sometimes an option on LFOs and oscillators, and sometimes it’s a component of its own. Either way, they operate similarly.
Sub Oscillator
Sub oscillators are an option on many oscillators that offer a waveform derived from the primary waveform, usually a square but sometimes other shapes, tuned at a fixed interval (usually an octave or two down, often switchable between multiple options) relative to the main oscillator’s pitch. This is used to “fatten” the signal and add/reinforce some harmonics.
Sync
Oscillator sync is a common feature in multiple-oscillator synths. Sync is typically an on/off feature, but some synths offer a few additional variations. We’ll cover sync in additional depth in the oscillator lesson, but for now it’s enough to know it’s a common option and to familiarize yourself with its sound, which is typically described as metallic, bright and cutting.
Mixer
Once you’ve got multiple oscillators, a sub oscillator and a noise source, you’re going to need a mixer to set the proper balance of all these elements. That’s where a mixer comes in. Typically the outputs of all the sound producing elements (oscillators, noise, sub osc) will go into the mixer, where the level of each can be set and balanced against the whole, then typically output to the filter. Often the mixer section’s controls are static, but sometimes it can be controlled by envelopes, LFOS and the like. Mixers can be transparent, adding little or nothing to the sound, or designed in such a way that they can be overdriven or saturated, adding harmonics to the sound.
Modulation Matrix
The final element we’ll cover in this lesson is the modulation matrix. You can think of this as a mixer and distribution center for your modulation/control signals. In other words, this lets you point your envelopes, LFOs and other control elements at various sound-creating elements to define how the sound elements are shaped by the control elements.
Designs vary widely – it might look like anything from a spreadsheet to a physical pin matrix. In operation, you select a source (usually a modulator) and a destination (a synth parameter that can be modulated/controlled) and set a depth (how much the destination control is affected by the source modulation). If your synth doesn’t have a modulation matrix (commonly called a mod matrix for short), it will instead typically have selectors of some kind at each modulation point that select between available modulation sources. Synths without a mod matrix are usually less flexible, with a smaller number of semi fixed destinations.
Exercises
1) Examine your synth and/or read its manual and determine if it has a mod matrix or if it uses a set of fixed/switchable destinations per mod source. Once you’ve determined which you have, look at the potential set of mod sources and destinations, and make a list of those that are most intriguing to you to explore.
2) Examine the synth you are using. Identify how many of each core element (oscillator, filter, amp, envelope, LFO) your synth has, and which of these new components (noise, sub oscillator, sync, mixer) are present on your synth. Additionally, make note of any components or elements that are present that haven’t been covered in these first two lessons. Make a list, mental or otherwise, of all of these.
3) One by one, try out the new features you identified in the previous exercise. Try out each of the techniques mentioned in the component’s description, such as trying different waveforms on each oscillator and trying the same waveforms but detuning them from each other. Try to get a sense for what kind of sounds might be possible with each of these.
4) Thinking about what you learned in the last exercise, return to the patches you created in the first lesson’s (Subtractive Basics I) exercises, especially if there were patches that you found difficult to create with the limited tools we used in that exercise. Try adding various components to each of those patches to see how it improves them and/or opens up new possibility spaces. For example, try adding a sub oscillator to a bass patch to see how it adds “beef” to the sound; try utilizing a second envelope on a sweep that opens the filter at a much slower rate than the amp is opened by its envelope; etc. If you come up with improvements, you should save them, either as new patches or updating the current ones.
5) Finally, let’s make some new patches. Ideally, your experimentations in steps 3 and 4 sparked some ideas for additional patches you can make using your new tools. Try and create a patch featuring each new component: something you couldn’t create without that component. For example, the infamous detuned “Reese bass” (a sustained, droning bass with lots of movement, usually from detuning the oscillators) can’t be created without at least two oscillators (or a unison function that simulates adding additional oscillators, but that’s a discussion for later). Try and create 5-7 patches at a minimum, again covering the basic synth sound types you frequently use/need.