Time to revisit the power of modulation and FM synthesis


Frequency modulation is not a new thing and it has certainly been a major force in many classic synth tracks over the years. Most notably of course was Yamaha´s introduction of the DX7. Now in 2016 we are seeing a revived interest in FM synthesis and one of the most recent contributions in this area is KORG´s ‘volca fm’ – a really sweet digital representation of FM synthesis in a portable package. While the Volca FM is a Korg device, the specifications (and colour scheme) are actually closer to that of Yamaha’s iconic DX7 synth. With six FM operators inside, it actually has two more than Yamaha’s recent Reface DXupdate of the DX7 – though the Volca FM only has three-voice polyphony compared to the Reface’s eight voices.


Yamaha had patented its hardware implementation of FM in the 1980s, allowing it and New England Digital Corporation (under license from Yamaha) to nearly monopolize the market for that technology until the mid-1990s. Casio developed a related form of synthesis calledphase distortion synthesis, used in its CZ range of synthesizers. It had a similar (but slightly differently derived) sound quality to the DX series. Don Buchla implemented FM on his instruments in the mid-1960s, prior to Yamaha’s patent. His 158, 258 and 259 dual oscillator modules had a specific FM control voltage input,and the model 208 (Music Easel) had a modulation oscillator hard-wired to allow FM as well as AM of the primary oscillator. These early applications used analog oscillators, and this capability was also followed by other modular synthesizers and portable synthesizers including Minimoog and ARP Odyssey. With the expiration of the Stanford University FM patent in 1995, digital FM synthesis can now be implemented freely by other manufacturers.

KORG introduced FM synthesis in products like the KRONOS synthesizer and the Oasys, much like Clavia did with the Nord Lead. Native Instruments’ FM8 – loosely based on the Yamaha DX – has become the instrument of choice for conjuring up cutting-edge bass growls by the likes of Skrillex, and Logic’s EFM1 can be heard providing the bass tones for dozens of deep house tracks. Also in the Propellerhead Reason Rack Extension there is also a nice DX7 replica.


Modulation means using one signal to affect another signal. A simple example of Frequency Modulationsynthesis (FM) consists of one oscillator (the MODULATOR), modulating the frequency of another oscillator (the CARRIER). This procedure produces additional frequencies called SIDEBANDS which form symmetrically around the original frequency of the CARRIER. For example, here is a simple SYD FM patch:

The volca fm is a natural progression of this. The volca fm is a three-voice digital FM synthesizer that completely reproduces the sound engine of a classic FM synthesizer, and provides compatibility with it as well. The volca interface makes it easy to manipulate distinctive FM sounds even if you’re not familiar with the complexities of FM synthesis. The 16-step sequencer that’s one of volca’s features provides new functions such as WARP ACTIVE STEP and PATTERN CHAIN that let you make even more powerful rhythm patterns. In addition to the active step function that lets you skip steps during a sequence, the volca fm provides new functions that enable you to generate more irregular rhythms. If the active step is fewer than 16 steps, you can use the warp active step function to compensate to occupy the same playback time as 16 steps; then by synchronizing the playback with another volca series unit, you can deliberately skew the step timing to generate truly unconventional performances. In a first for the volca series, the volca fm is also equipped with an arpeggiator. By using this in conjunction with a motion sequence you can create extremely eccentric rhythm patterns. Furthermore, the pattern chain function lets you connect multiple sequence patterns for successive playback, making it possible to construct large-scale developments of 32, 64, or even 256 steps by joining up to 16 sequences.


A polyphonic digital synthesizer that completely reproduces a classic FM sound engine. More about volca fm at:http://www.korg.com/volca_fm/