Hello, I’m Jooyoung Kim, a sound engineer and music producer.
In my last post, I talked about my thesis, but here’s a funny update: the journal that desk-rejected my paper (Transactions on Consumer Electronics) sent me an email asking me to be a reviewer. It’s a bit of a niche SCIE journal, but still Q1-Q2 level, so I was pretty floored. I’m flattered, but since I haven’t even graduated with my master’s yet and my main paper isn’t published, I politely declined. Who am I to judge someone else’s work at this stage? 😅
Now, let’s get to today’s topic: picking up where my synthesizer series left off last month, we’re diving into modulation synthesis, focusing on the legendary FM (Frequency Modulation) synthesis, made famous by the Yamaha DX7.
Here we go!
Modulation
What is modulation? I touched on this in my Basics of Mixing series a while back:
In short, modulation involves using an external signal (the modulator) to alter specific parameters of another signal (the carrier), changing its sound. The external signal is often a Low Frequency Oscillator (LFO), but other sources can be used too.
Types of Modulation
| Type | Description |
|---|---|
| AM (Amplitude Modulation) | Modulates the amplitude of the carrier signal using a modulator. Think tremolo effects. |
| FM (Frequency Modulation) | Modulates the frequency of the carrier signal. Famous for metallic and bell-like sounds, as heard in the Yamaha DX7. |
| PWM (Pulse Width Modulation) | Modulates the pulse width of a square wave. Common in analog synths and compressors like the PYE Compressor. [photo] |
| RM (Ring Modulation) | Multiplies the carrier and modulator signals, producing only the sum and difference frequencies (a+b, a-b). |
| PM (Phase Modulation) | Modulates the phase of the carrier signal. Fun fact: the DX7 is technically PM-based but was marketed as FM for mass appeal. |
AM and FM might sound familiar from radio broadcasting. FM, in particular, shines in synths for creating those iconic metallic or bell-like tones. There are also other modulation types like Cross Modulation, Wavetable Modulation, and Granular Modulation, but I’ll cover those in their respective sections later. 😄
FM (Frequency Modulation)
Meet Dr. John Chowning, the mastermind behind FM synthesis, developed in the late 1960s at Stanford University. [photo] FM synthesis modulates the carrier’s frequency with a modulator, producing complex, irregular harmonics that are perfect for metallic and bell-like sounds.
FM synthesis was a staple in 1990s video games and software. Yamaha’s YM2612 chip (aka OPN2) powered sound cards like AdLib and Sound Blaster, as well as consoles like Sega’s Mega Drive and Fujitsu’s FM Towns Marty.
In 1971, Dr. Chowning saw the commercial potential of FM synthesis and pitched it to companies like Hammond and Wurlitzer, but they all passed. Yamaha, however, struck a deal, securing a one-year license and exclusive rights to the technology by 1975. Looking at its massive success, both Yamaha and Dr. Chowning had incredible foresight! 😊
In 1980, Yamaha released the GS-1, their first FM synthesizer, with only 16 units made for studio use. It was used by legends like Stevie Wonder, Chick Corea, Herbie Hancock, and Toto.
Priced at $16,000 back then—about $66,000 today, or roughly 1 billion KRW—it was a luxury item.
The GS-1’s unique sound was a hit, leading Yamaha to release the more portable and affordable GS-2, as well as the CE-20 and CE-25 Ensemble series for the home organ market.
Yamaha’s PAMS and DX Series
Yamaha later developed the PAMS (Programmable Algorithmic Music Synthesizer), which offered flexible programming but had too many parameters.
To simplify, Yamaha’s engineers made the modulator and carrier envelope generators share parameters, leading to the DX series: DX-1 (73-key flagship), DX-5 (76-key, budget version of DX-1), DX-7 (6-operator), and DX-9 (4-operator).
The Yamaha DX7 is arguably the most iconic FM synthesizer, selling 200,000 units worldwide at 248,000 yen each—a massive commercial success.
It featured six sine wave operators that could act as either carriers or modulators, with 32 selectable sound algorithms to switch their roles. In the diagrams, each vertical line represents a sound synthesis path, with parallel lines combining, the bottom being the carrier, and those above it modulators.
The DX7 also supported MIDI, often paired with sequencers like the Yamaha QX-1. Beyond bell-like sounds, it’s famous for electric piano (FM EP) and bass (FM Bass) patches—search for those terms, and you’ll find tons of resources. 😄
In one sentence: FM synthesizers excel at creating sounds with irregular harmonics.
Modern FM Synths
Some great virtual instruments carry the DX7’s FM legacy:
If you buy through these links, I earn a small commission, which helps me keep going—thank you! That said, I recommend waiting for bundle sales to grab these at a better price. I previously covered Arturia’s V Collection X bundle, which is worth checking out:
Don’t just take my word for it—try a free virtual synth, play around, and hear the sounds for yourself!
That’s it for today. See you in the next post! 😊
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