Let's have a look at the Korg Volca FM, a neat little digital synthesiser module in a tiny box. It was launched back in 2016 as the fifth in Korg's Volca range - after the Beats, Bass, Keys, and Sample, in roughly that order - and it's still on sale brand new today, if you can find one still in stock.
What is the Volca FM? It's a three-voice digital synthesiser module that uses
Frequency Modulation synthesis, which was made famous by Yamaha's mid-80s DX
synthesisers, particularly the DX7. In fact the Volca FM uses the same FM
engine as the DX7, and it can even load and use DX7 patches, of which there
are
masses available online.
One caveat is that the Volca FM only has three-voice polyphony vs the
original DX7's sixteen voices. Why is this? I have no idea. Perhaps the
engineers who developed the other Volcas realised that the CPU had enough
horsepower to do a little bit of FM, so they went ahead and made up a
prototype, and it worked, and Korg put it into production. Who knows.
What is FM? It's a type of synthesis that generates sounds by
modulating the frequency of one waveform with another waveform. It's one of the
oldest forms of sound synthesis, because it's technically simple. A lot of
the clanging, dissonant electronic music of the 1940s and 1950s was made with
frequency modulation, using analogue oscillators linked in pairs. In
this image I've set up a pair of analogue oscillators into an FM configuration:
Notice how the output of oscillator one is controlling the pitch input of
oscillator two. The end result is a clangy, metallic sound that becomes more
or less dissonant when I tweak the pitch of the two oscillators.
In the 1960s a chap called John Chowning worked out a way to implement FM
synthesis with computer software. This caught the attention of Yamaha, who
realised that they could use digital FM to produce a range of instruments
that didn't need analogue oscillators and filters, so in the 1970s they
licensed Chowning's algorithms.
Yamaha's early FM synthesisers were either toys, or extremely expensive
performance instruments, but as the cost of computer chips came down Yamaha
managed to miniaturise their FM engine into a huge range of devices, including
computer sound chips, arcade machines, games consoles, and eventually mobile
phones. Whoever licensed the technology was very forward-thinking. The
company's most visible success was the DX7 of 1983, which was followed by an
extensive line of DX synthesisers.
Lots of classic arcade games had FM sound chips. This is R-Type. The Sega
Megadrive / Genesis also had an FM chip, which was used to impressive
effect by Yuzo Koshiro for the Streets of Rage games.
FM has a distinctive sound. Its clashing waveforms are particularly good at
clanging, percussive, glassy noises, per this early track from 1973:
If the DX7 had only been able to make metallic sounds it would have had a
niche appeal, but Yamaha had the good fortune to have some genius programmers.
They gave the machine a bunch of killer presets, particularly the electric
pianos and basses, but also brass and bell sounds as well. Furthermore the DX7
had a state-of-the-art specification - MIDI, 16-voice polyphony, expandable
memory, with a velocity-and-aftertouch-sensitive keyboard, even breath control
- wrapped up in a sleek metal case, and as a consequence it became a best-seller.
On the downside the DX7's implementation of FM had trouble generating sawtooth
waveforms, which meant that its strings in particular sounded very weak.
Furthermore it was difficult to program, and the sheer ubiquity of its pianos
and basses in pop music meant that the FM sound was very old-fashioned by the end of
the 1980s. There was a market for third-party patch cartridges, but even the
best DX programmers couldn't compete with the lush soundscapes of sample-based
synthesisers, so for a few years after the DX7's heyday it had an air of
naffness about it.
Ironically a lot of Warp Records' early classics were made with FM
synthesisers - FM is all over Aphex Twin's
Selected Ambient Works records, because the only instruments he
could afford were cheap second-hand FM synthesisers - but Mr Twin and his
colleagues masked it with masses of reverb, and in a world of sample-based
acts such as The Orb and Future Sound of London FM synthesis sounded very
old-hat. In response Yamaha scrapped its last pure FM flagship, the V80FD, in
favour of the SY-series, which used a mixture of FM and sample-based synthesis
instead.
FM has periodically come back into fashion. There was a 1980s retro wave in the early 2000s, fed by Yamaha's DX200 groovebox and Native Instruments' FM7 VST FM emulation, and about ten years later vapourwave made the sound of the 1980s hip again. As of 2022 FM7 has becme FM8, the hip kids have the Elektron Digitone, and FM now seems to have carved out a little niche, which is a lot better than being a naff joke.
FM will probably remain a niche, because it's hard to conceptualise and program effectively. Simple two-operator carrier-plus-modulator
FM isn't all that difficult. Mutable Instruments' Plaits has a simple two-operator
FM model that can be tweaked with just three knobs (timbre, morph, and
harmonics):
The idea is that the carrier produces the sound and the
modulator affects the carrier. If you apply an envelope to the
modulator the sound of the carrier changes over time, mimicking e.g a filter
sweep. If you go further and modulate the modulator with a second modulator you can produce a range of tonally complicated noises that mutate over time.
The DX7 had six oscillators, although Yamaha called
them operators, each with its own multi-stage
envelope.
The operators could be arranged in 32 different configurations - e.g. three carrier/modulator pairs, or a stack of modulators operating on each other, or a bank of carriers with no modulators, etc - with the output of some operators being fed back into
themselves. To make things even more tricky the DX7's interface was a
button-heavy select-one-parameter-then-alter-it affair that did nothing to
encourage experimentation.
The Volca FM can also be edited with the front panel. Remember the Volca FM? I
was talking about the Volca FM. The entire FM engine is buried away in the
menus, but Korg thoughtfully put the most useful controls on the front panel,
as above. The carrier envelope acts as a VCA, the modulator envelope acts as a
VCF-stroke-wavefolder, and the algorithm knob makes the sound more or less
clangy.
One of the DX7's limitations - not so much of the DX7, but of 1980s digital
synthesisers in general - was the lack of real-time parameter tweaking. In
particular you couldn't tweak two parameters at once. The Volca FM on the
other hand is in always-write mode, so you can tweak the panel controls while
a sequence is playing through it. This explains why there's a big velocity
slider on the front panel. The preset sounds are all designed so that if you
play a sequence with the built-in sequencer while tweaking the velocity slider
the end result mimics the effect of tweaking the VCF with an analogue synth. It helps compensate for the odd decision not to support MIDI key velocity.
You can still access all of the underlying parameters, but this involves menu
diving. In practice it's a lot easier to use
Dexed, which is
a freely-available emulation of the DX7. If you plug the Volca FM into your
computer's MIDI output you can use Dexed to transmit patches to the Volca FM,
although unfortunately you can't suck patches out of the FM with
Dexed:
You can see why the DX7 was so difficult to program. Each operator has a stack
of parameters, on top of which there are a set of global controls. Fortunately Dexed has an algorithm diagram that makes the flow of sound easier to fathom. In the screenshot above operators 1 and 3 are the
sound-producing carriers and operators 2 and 4 are the wibbly-wobbly
modulators. They're arranged in two parallel groups, as if they were two separate oscillators.
Dexed has a few limitations. It sticks to the DX7's specification, so there's
only one LFO. It also doesn't work with realtime parameter modulation, so you
can't (for example) use a MIDI LFO to tweak Dexed's parameters while you play
a sequence. Nonetheless after using it for a while I was struck by how
much potential the DX7 had lurking inside its metal case. It's particularly
good at making patches that evolve gradually over time, because the envelopes
have a wide range.
After writing this blog post I went back and made
a piece of music entirely with Dexed, plus a little bit of Plaits and the
analogue FM pictured above, the latter two making the swooping noises at the
beginning:
Yamaha's later FM synthesisers added more waveforms, although sadly Dexed only
emulates the original DX7 (and the cut-down DX9), not Yamaha's later FM
designs. During the 1980s the DX7's patches appeared in unaltered form on
several hit records, but ambient producer Brian Eno went to the trouble of
learning how to program his DX7 - he concentrated on simple sounds fed into a
chain of reverbs, but the unearthly tones of Eno's DX7 are all over
The Shutov Assembly and Thursday Afternoon. There's some
debate as to whether it's on Apollo as well; that album was
released in the same year as the DX7, and most concrete sources say that Eno
actually used analogue synthesisers instead.
If you're very busy the Volca FM has 32 presets, and they're pretty good, and
because this is the twenty-first century Korg didn't feel the need to make
two-thirds of the presets imitations of oboes etc. The presets are
essentially FM's greatest hits - several twangy basses, some
nice chimes, a slightly incongruous electric piano - but they're generic enough to be usable. For fun I
decided to make a piece of music entirely with the Volca FM's presets, albeit
put through lots of effects:
The Volca FM also has a sixteen-step, sixteen-pattern sequencer. You can chain
sequences together, although as far as I can tell you can't program a song -
e.g. the sequences play 1-2-3-4 in a loop, you can't set them to play
1-1-2-1-2-3-4 etc. I admit that I've barely touched the sequencer. It has
limited realtime control. You can turn off notes, and set it to
extend shortened patterns so that they fit into a 16-step timescale, but you
can't alter notes as you're playing. I prefer to plug my FM into an Arturia
BeatStep instead.
The Volca FM has a single MIDI input port, but no MIDI out. It has standard
Volca two-pulses-per-quarter-note audio sync ports that will drive Pocket
Operators as well as other Volcas. The sync out port will also send the FM's
internal memory to other Volca FMs. My hunch is that you could probably record
this as an audio file for backup purposes.
There's a single stereo 3.5" jack plug for audio output. It may be my
imagination but the FM sounds less noisy than the mostly-analogue Volca Beats,
with less aliasing than Yamaha's first wave of DX synthesisers. For the song
above I didn't feel the need to use a noise gate to get rid of the background
hiss. The FM's sound engine is mono, but it has a stereo chorus effect, which
is why it has a stereo output.
There's also an arpeggiator. As mentioned above I find it easier to use
software arpeggiators, but the arp will integrate with the built-in sequencer,
and I suppose if you were sufficiently dedicated you could make sequencers
longer than sixteen steps by turning the tempo down and filling the space with
arpeggiated notes.
Does the Volca FM make any sense at all, given that Dexed is free? If you're
purely a composer then no, the FM doesn't make any sense. Dexed can load the
Volca FM's
default patches
and play them in pristine digital clarity, with sixteen voice polyphony and
velocity sensitivity, without having to bother with cables. It's also a lot
easier to edit. The three-voice polyphony and lack of MIDI velocity limits its
value as a straightforward FM module, a la the FB-01.
For live performance however the Volca FM is a much better idea. It's
portable, it runs on batteries, it syncs to analogue drum machines, and it's
great fun as a dedicated FM bass box when paired with a hardware sequencer.
The front-panel controls are well-thought-out for live performance and the
presets are surprisingly good. I think of it as a TB-303-style device with an
FM engine that just happens to be able to load strings and piano patches as
well as basses and rhythm devices, rather than for example a DX7 replacement.
Cost-wise I bought mine for just over a hundred English pounds, but it has
gone up since then. It's still however cheaper than the most obvious physical
equivalents, the £600 Korg OpSix and the £400 Yamaha Reface DX, which only has
four-operator synthesis. It's also a lot cheaper than an actual second-hand DX
synthesiser, on account of the fact that eBay sellers are convinced that
vapourwave is still a thing.
And that's the Volca FM. It has some odd design choices and is a luxury if you don't intend to play live, but it's good
fun if you do. Think of it as a bass module that can play other sounds, goodbye.
EDIT: As if by magic Korg announced a Mark Two Version in mid-April 2022. The Volca FM 2 ups the polyphony to six notes and adds MIDI velocity response, as well as rejigging the MIDI - it uses a pair of 3.5" jacks for MIDI IN and OUT, instead of just having a single MIDI IN five-pin DIN socket. Beyond that the FM engine is apparently the same.
