Tag: Synthesis

Advanced Synthesizers and Gear – (3) VCO, VCF, and VCA

Hello! I’m Jooyoung Kim, an audio engineer and music producer.

Today, I’d like to talk about the essential components of sound generation in a synthesizer. Every synthesizer or modular system utilizes these three core functions: the VCO, VCF, and VCA.

Their functions are explained below:

  • VCO (Voltage Controlled Oscillator): Generates basic waveforms such as sine, square, sawtooth, and triangle waves.
  • VCF (Voltage Controlled Filter): Processes the signal from the VCO by attenuating specific frequencies. Common types include low-pass, high-pass, and band-pass filters, which are essential for sound design.
  • VCA (Voltage Controlled Amplifier): Acts as a gate or gain stage that shapes the volume of the audio signal over time, typically controlled by an envelope generator (which defines the attack, decay, sustain, and release of the sound).

VCO – Basic Waveforms

Doepfer A-110-1 Standard VCO

You can easily find these waveforms on a VCO module. The image above is an example from Doepfer A-100 module system; the waveforms are depicted on the panel, located below the output connectors.

As you can see, there are four types of basic waveforms: sine, square (pulse), sawtooth, and triangle. They are created by combining various harmonics, which can be expressed using mathematical equations.

Therefore, I will explain all types of waveforms with graphs and equations.

Sine Wave

Sine wave is the most fundamental wave. It is defined by the function:

f(t)=Asin⁡(ωt+ϕ)f(t) = A \sin(\omega t + \phi)
  • A: Amplitude (peak value)
  • ω: Angular frequency
  • ϕ: Phase shift
  • t: time

Square Wave

Square wave is a periodic wave that switches between two levels. It can be represented as an infinite summation of odd harmonics of sine waves:

f(t)=4Aπ∑n=1,3,5,...∞1nsin⁡(nωt)f(t) = \frac{4A}{\pi} \sum_{n=1,3,5,…}^{\infty} \frac{1}{n} \sin(n \omega t)
  • A: Amplitude (peak value)
  • ω: Angular frequency
  • t: time

Sawtooth Wave

This waveform increases linearly and drops instantly. It contains all integer harmonics:

f(t)=2Aπ∑n=1∞(−1)n+1nsin⁡(nωt)f(t) = \frac{2A}{\pi} \sum_{n=1}^{\infty} \frac{(-1)^{n+1}}{n}{\sin(n \omega t)}
  • A: Amplitude (peak value)
  • ω: Angular frequency
  • t: time

Triangle Wave

It is similar to a sawtooth, but symmetric. It consists only of odd harmonics, but with a faster decay of amplitude:

f(t)=8Aπ2∑n=1,3,5,...∞(−1)(n−1)/2n2sin⁡(nωt)f(t) = \frac{8A}{\pi^2} \sum_{n=1,3,5,…}^{\infty} \frac{(-1)^{(n-1)/2}}{n^2} \sin(n \omega t)
  • A: Amplitude (peak value)
  • ω: Angular frequency
  • t: time

Each waveform has distinctive sound characteristics, and these basic waves are the foundation of synthesizers.

As a side note, because the sawtooth wave contains the richest harmonics among these basic forms, it is frequently used to create pad sounds to fill up the background.

VCF – Basic Filters

Behringer 121 Dual VCF

Basic filters are typically categorized into three types: low-pass (high-cut), high-pass (low-cut), and band-pass. Filters have various parameters, but I will introduce only the basics today.

  • Cutoff Frequency: Due to the characteristics of the Butterworth filter (the standard filter used in audio), 3 dB of attenuation occurs at the cutoff frequency.
  • Slope: 6dB/oct is the fundamental slope. This represents one ‘pole’ of the filter. Since filter order (the number of poles) determines the steepness, you will commonly see slopes of 12, 18, 24 dB/oct, etc.

Many filter modules include a resonance function that emphasizes frequencies near the cutoff frequency. When modulated, the fluctuating cutoff frequency also causes the resonance peak to shift. This shifting creates the perception of pitch fluctuation, even though the actual fundamental pitch remains unchanged.

VCA – ADSR Envelope Generator

WYWS MS507

Although I have covered the ADSR concept previously, I will break it down again for those who are new to it. While a VCO and VCF are essential for creating and shaping a sound, they do not have a built-in gate mechanism to trigger or shape the signal’s output. This is where the ADSR envelope comes in.

ADSR stands for Attack, Decay, Sustain, and Release. These four parameters define how the amplitude of a signal changes over time as it passes through a VCA.

  • Attack (time): The time it takes for the sound to reach its peak level from the moment a key is pressed.
  • Decay (time): The time it takes for the sound to drop from its peak level to the designated sustain level.
  • Sustain (level): The volume level that the sound maintains while the key is held down.
  • Release (time): The time it takes for the sound to fade away completely after the key is released.
Behringer 182 sequencer

In modular synthesizers, sequencer modules are often used instead of keyboards.

So far, we have explored the essential building blocks of a synthesizer. These modules serve as the ‘alphabet’ of sound design; therefore, becoming familiar with them is crucial for mastering these complex musical instruments.

That’s all for today. I hope this overview helps, and I look forward to seeing you in the next post!

Basics of Synthesizers (9) – PCM Synthezisers (Pulse Code Modulation)

Hello! This is Jooyoung Kim, a mixing engineer and music producer.

Today marks the final article in my ‘Basics of Synthesizers’ series. I may add more articles in the future if I come across interesting topics, such as modular synthesizers (which I’ve recently started exploring—stay tuned!). For now, however, I feel I’ve covered enough to complete this category.

Let’s start!

The PCM (Pulse-Code Modulation) method is essentially a form of digital sampling that represents analog signals through discrete digital steps. While modern virtual instruments load massive recorded data into RAM to trigger sounds via MIDI, hardware PCM instruments utilize ROM in much the same way—storing high-quality, pre-fabricated waveforms that are ready to be played instantly.

Because these instruments play back pre-recorded samples from internal memory rather than synthesizing them from scratch or recording new ones, they are commonly called Romplers (a blend of ROM and Sampler). Unlike pure samplers, Romplers focus on the immediate reproduction of realistic acoustic and electronic sounds, making them the backbone of music production since the late 1980s.

Implementing such a system requires significant computational power and memory resources. Thanks to rapid technological advancements, these requirements were finally met in the late 1980s. During this period, ROM prices decreased significantly, allowing for the emergence of instruments installed with long-cycle samples, which offered a level of realism previously unattainable.

The Kurzweil K250 was the forerunner and the first PCM-based synthesizer.

These instruments utilized samples of each sound phase—attack, decay, and release. This approach allowed them to produce more realistic and dynamic sounds. Many people requested authentic sounds and in the 1990s, these kinds of instruments became mainstream.

The PCM method is now the standard for recording systems, DAWs, and virtual instruments. You might assume that modern virtual instruments are simply evolved versions of PCM-style synthesizers, and that is largely true. However, as many musicians today find themselves missing the characteristically thin and lo-fi sounds of vintage PCM hardware, many software companies now provide these classic instruments in digital formats.

The Korg M1

The Korg M1 was a famous PCM-style synthesizer in the late 1980s. It became one of the best-selling synthesizers in history. Its specific presets, such as the M1 Piano and Organ 2, defined the sound of 1990s house and dance music. These sounds were so distinct that they are still widely used in modern electronic music productions.

https://synthanatomy.com/2024/03/hypersynth-hcard-101-expands-your-korg-m1-ws-ds8-or-a1-with-more-external-memory.html

The M1 also featured external card slots, allowing users to expand its sound library by inserting PCM and Program cards, providing additional waveforms and presets beyond its internal memory.

The E-mu Proteus Series

The E-mu Proteus series were also famous PCM-style synthesizers in the late 1980s. Unlike the Korg M1, they were rack-mount module swithout a keyboard. they were designed to provide high-quality samples at a lower price point, making them standards in many project studios. Their presets were widely used in film and television scores, including the iconic whistling sound in The X-Files theme.

The later models of the Proteus series were also highly expandable; they featured internal slots where users could install additional ROM SIMMs, such as the Orbit or Mo Phatt cards, to instantly add hundreds of new sounds tailored to specific genres.

The Roland JV-1080 and JV Series

In this perspective, you should know about the Roland JV series. The JV-1080 and 2080 are legendary icons of the Rompler era. Released in the mid-1990s, these units became industry standards, found in almost every professional studio worldwide. Their massive success came from their ability to provide high-quality, ready-to-use PCM samples through various expansion boards, allowing musicians to access realistic orchestral, synth, and ethnic sounds instantly without the need for complex sampling.

This picture shows sound expansion slots of the JV-1080 synthesizer

You can hear the sounds of the official Roland Cloud recreation of the JV-1080 in this video, as demonstrated by ADL-MusicLab. It’s easy to associate these sounds with 1990s and 2000s classic pop, TV commercial soundtracks, and film scores.

The Korg Trinity and Korg Triton

The Korg Trinity and Triton were also iconic instruments of that era. Beyond hip-hop, these workstations defined the sound of mainstream pop. For instance, The Neptunes were among the most famous users of the Triton, while the instrument’s distinctive patches were also featured in many of Britney Spears’ hits. These units weren’t just for one genre; they were the great tools for producing the global hits of the early 2000s.

Similar to the JV series, the Triton also offered expandability through EXB-PCM boards and even allowed for the addition of the MOSS synthesis engine.

The Yamaha Motif

The Yamaha Motif was another famous instrument of the era. It produced more realistic sounds than its competitors, so its Acoustic Piano, Rhodes (E. Piano), and Acoustic Guitar presets were widely used in churches. In particular, it became a standard keyboard for global worship teams like Hillsong and Bethel, defining the sound of modern gospel music. The Motif stood out for its PLG expansion boards, which allowed users to add entirely new synthesis engines, such as FM synthesis, directly into the unit. (In South Korea, the Motif is still widely used in worship services.)

Interestingly, the thin and lo-fi quality of these sounds has become a source of classic pops. If you want to recreate an authentic vintage pop vibe, I highly recommend exploring these types of virtual instruments.

With this, I would like to conclude my ‘Basics of Synthesizers’ series. I have put a lot of effort into researching and explaining these concepts, and I hope you found them helpful.

Thank you for reading, and I will see you in the next article!

Basics of Synthesizers (8) – Phase Distortion Synthesis

Hello! This is Jooyoung Kim, a mixing engineer and music producer. Today, I’ll talk about the phase distortion synthesis method and synthesizers.

This post includes a few affiliate links. If you make a purchase through them, I may receive a small commission, which helps me keep writing…^^

In my last post, “Basics of Synthesizers (4) – Modulation Synthesis and FM,” I mentioned that Yamaha’s DX7 was called an FM synthesizer, but in reality, it uses phase modulation synthesis. Also, I already explained the phase modulation in short. Therefore, I will not discuss phase modulation further.

However, there is one more signal synthesis method, Phase Distortion (PD), invented by Casio, which uses the phase of the signal. Its principle is similar to that of Phase Modulation, which was invented by John Chowning.

https://en.wikipedia.org/wiki/Phase_distortion_synthesis#/media/File:Casio.CZ101.resonance.png

The picture illustrates how the PD method works. First, you can see that the basic frequency counter resets to zero after a certain period – (a).

There is also another frequency counter with a slightly higher frequency than (a), which resets to zero when the (a) signal resets to zero – (b).

(b) signal is used the phase value of the sine signal – (c).

The inverted base signal (a), which is used as a windowing function that goes to zero at the end of the period -(d).

The final output signal obtained by multiplying (c) by (d). This multiplication levels out the sudden jump in (c), resulting in a smooth, filtered PD waveform – (e).

https://commons.wikimedia.org/wiki/File:Casio_CZ-101.jpg

The Casio CZ series was the hardware synthesizer to which the PD method was applied.

https://commons.wikimedia.org/wiki/Category:Casio_XW-P1#/media/File:Casio_XW-P1_Synthesizer_(49916418603).jpg

The Casio XW series also featured the PD method in its synthesis engine.

Click the image to purchase Arturia’s CZ-V virtual instrument from Plugin Boutique

Phase Distortion (PD) method hardware synthesizers are not sold by other companies besides Casio. Therefore, if acquiring the real hardware is too expensive or inconvenient, using software emulations like Arturia’s CZ-V is a handy alternative.

That’s all for today. See you in the next post!

Basics of Synthesizers (7) – Granular Synthesis

g

Hi! This is Jooyoung Kim, a mixing engineer and music producer. Today, I’ll introduce granular synthesis, which is composed of “grain” units.

The principle of this type of sound synthesis is very similar to the concept of sampling. Granular synthesizers take small parts of a sample and store them as units. Those units are called “grains.” That is where the name “Granular Synthesis” comes from.

The grains have lengths ranging from approximately 1 to 100 ms, and these samples can be played at different times, phases, speeds, and frequencies in a granular synthesizer. Thus, cloudy sounds that resemble long reverberations and continuous tails are produced by these manipulations.

In 1947, Dennis Gabor introduced this concept, which was first implemented in a computer in 1974 by Curtis Roads, an electronic music composer specializing in granular and pulsar synthesis. The spans are quite long, aren’t they?

The emergence of granular synthesizer hardware was significantly delayed due to the large computational requirements and high CPU speed needed for the calculations. Thus, the real-time version of this synthesizer emerged 12 years after the use of granular synthesizers in Curtis Roads’ music.

DMX-1000 (https://120years.net/dmx-1000-signal-processing-computer-dean-wallraff-usa-1978/)

The real-time granular synthesis was invented by Barry Truax, a Canadian composer. This synthesis was processed by the DMX-1000 computer.

Naturally, you might wonder about the existence of physical hardware, as with other synthesizers. The upper photo shows the modern, dedicated granular synthesizer hardware, the GR-1, which was released in 2017.

This shows that this kind of synthesis processing requires a lot of computing resources. And this means that many virtual synthesizers using this method require significant computing power.

Granular effect “EFX Fragments” by Arturia (affiliate link—if you purchase this plugin through it, I will receive a small commission to support my work :)).

However, for implementation in DAWs (Digital Audio Workstations), no physical hardware is needed to use granular synthesis. Arturia’s EFX Fragments is a great example.

Granular effect “Portal” by Output (also affiliate link)

Output’s “Portal” plugin is another excellent granular effect.

This is the official video of the EFX Fragments. You might hear the “shimmering sound” from it.

This sound could be effective in ambient music that requires long tails on the sounds. I like these sounds, but I’ve never used them in my music… ^^;; However, someday I will…

OK, I’ll wrap this up today. See you in the next post!