There are a zillion synths out there and they all look different and overwhelming. Most of them come with labels, but if you don’t understand the terminology you’re still staring at it like it’s in Arabic. Some YouTube surfing directed me to a fantastic three part tutorial from The New York School Of Synthesis by Dan Friedman. The video is recorded in the 80’s so it can feel a bit out-dated, but Dan gives a magnificent explanation to get you up to speed on synthesis. I’ll post the video of the first part below this article, but lets break down the fundamentals.
The three elements of sound
To understand synthesis you have to understand what are the elements that make sound (apart from vibrations).
- Pitch — the basis of a sound. Gives the sound its tone.
- Volume — the shape of the sound.
- Timbre — the character of the sound (harmonics).
Pitch This is the section that sets the frequency. By adjusting the frequency you adjust the tone. The pitch allows you to generate anything from a low note all the way up to a high note.
Volume Volume isn’t just the level of the sound. It’s also where the shape of the sound is formed. A violin has a different shape than an electric guitar. This is set in the volume envelope, which we’ll discuss later on.
Timbre This component gives the sound its unique character/tone/brightness. Timbre is what makes the difference between a saxophone and a trumpet. This is due to the harmonic structure. Harmonics are sets of multiple notes, which are higher and softer in volume, which are stacked upon the original note. When a sound contains more harmonics the sound will be brighter. Less harmonics make a sound darker and dull.
The seven main components of a synthesizer
- Amplifier — also know as VCA or DCA
- Oscillator — also know as VCO, DCO, OSC, Frequency
- Filter — also known as modulator, VCF, DCF
- Volume envelope
- Filter envelope
- Pitch envelope
- LFO — low frequency oscillator
Amplifier Takes care of the overall volume of the sound. Also sets the balance between different oscillators.
Oscillator The oscillator is where you set the basis of your sound. Here you choose your waveform and the pitch of the sound. If you want to make a flute you put the pitch high and if you want to create bass you set it low. This is also the section where you choose the waveform. The waveform determines the character of the sound. If you use multiple oscillators you can give each oscillator it’s own waveform and pitch.
The five most common waveforms
- Square wave
- Saw tooth wave
- Triangle wave
- Pulse wave
- Sine wave
When this is done you have the foundation of your sound. It will probably not sound very interesting, but the body is there.
Filter This is the section that adjusts the harmonic content/timbre of the sound. You can make the sound bright or filter it and make it darker, depending on your needs.
- Cut-off/Frequency (filter cut-off point) This is the part where you set the cut-off point for the filter. There are different kinds of filtering like high pass and low pass. Some synths also allow you to set the slope of the filter cut off point. The cut-off sets the working edge of the filter.
- Resonance Resonance gives the frequency a little boost at the point of the filter cut-off. This adds some harmonics and can make filter changes more noticeable.
- Envelope amount This sets the value in which the filter envelope (more on envelopes later) has effect on the original sound.
There are envelopes for different sections, like filter and pitch envelopes. The most common one is the volume envelope. The envelope is a group of settings, which is routed to the amplifier (in case of volume), which sets the shape of the sound. The most common sections of an envelope are: Attack, Decay, Sustain and Release. ADSR in short.
- Attack: the time it takes for the sound to go from 0 to max (peak).
- Decay: the time it takes to travel from max to sustain.
- Sustain: the sound you hear when you keep the key pressed.
- Release: The time it takes for the sound to travel from sustain level back to zero.
Attack, decay and release are rates. Sustain is a level.
Filter envelope — harmonic envelope (timbre filtering) For the filter envelope the same ADSR principle goes. Only this time the envelope manipulates the filtering from the sound.
Pitch envelope Ones again the same concept as the volume envelope, only this time it adjusts the oscillator pitch. With a slow attack the pitch from the sound changes gradually. Comes in handy when making automated pitch bends or swoop effects.
Frequency Modulation This is a way of synthesis in which one waveform is used to modulate (change) the other waveform. This creates very complex waveforms and thus very interesting sounds.
LFO (low frequency oscillator) An LFO functions basically the same as a normal oscillator, only the frequencies are so low we can’t hear them. Therefor LFO’s aren’t used to create sound. They are used to modulate sounds from different oscillators. The LFO can be used to modulate a variety of components. The LFO also uses waveforms. These waveforms are used to modulate the frequency of other oscillators creating a wide variety of effects like:
- Pitch modulation = vibrato (oscillator modulation)
- Volume modulation = tremolo (amplitude modulation)
- Filter modulation = harmonic content
- Pulse width modulation
LFO depth sets the mix of the effect and LFO amount the speed of the effect. In a nutshell the LFO wiggles the sound.
This basically sums up every synthesizer ever made. Some have more functions, some use different labels, but they all obey to the seven basic components of synthesis. Obviously we’ve only scratched the surface and still have a long way to go to fully understand synthesis, but at least we now know what all these fancy buttons and faders on synthesizers are. If you have an hour for yourself I highly suggest watching the video below with the amazing Dan Friedman. He pulls of a great job making boring theory understandable in a funny way.