Before we go any further, let's define these terms a little. They're more slippery than they first appear. (Ask Marc Doty, whose epic series on polyphony is linked at the bottom of this article.) We can get a basic understanding if we put on our philologist (word-knower) hats. From the Greek, mono means one; poly means many. Phony means voice. So, polyphony is many voices, while monophony is just one voice. A choir or a soloist.

But what is a "voice" when discussing synthesizers? Attempting to define a voice is where things get slippery. Some people describe the difference between monophonic and polyphonic synths as the ability to play chords. Except, many monophonic synths have multiple oscillators, which can be tuned to the intervals of a chord. Then, they might clarify that it's about being able to play different notes on a keyboard simultaneously.

However, if we look at a eurorack module like Mutable Instruments' Rings, it can play multiple notes at once, just not at the same time. So is it not polyphonic? You can see how this seemingly simple question has a lot of complicated answers.

While debates about those complicated answers will continue to rage on despite our best efforts, I'd like to present the difference between monophonic and polyphonic in the way that I have come to think of it. And that is in terms of expression. To make this even more precise, let's do away with notes and chords for a moment and speak only of sound (after all, some synthesizers strive for the atonal).

A monophonic synth allows you to express one sound at a time, while a polyphonic synth can will enable you to express more than one sound simultaneously.

Suppose we return to our example of the mighty multi-oscillator synth, one not so different in my imagination from the vaunted Moog Model D. In that case, we see that while it can form chords from its arrangement of oscillators, it can only express one chord at a time. Resoundingly monophonic. Meanwhile, the Mutable Instruments' Rings is restored to an untroubled position in the pantheon of polyphonic instruments. While only one of its voices can be triggered at a time, those voices can overlap and express different sounds simultaneously.

We return to our conundrum with definitions in place: do we choose a monophonic synth or a polyphonic one? At first glance, it might appear the choice is simple. More is always better, right?

Context is critical here. Polyphonic synths and monophonic synths can serve different purposes, and it is often the case that the limitations of one are advantages of the other. I used the example of a choir and a soloist before. The choir can make beautiful harmonies, but it can't take the lead like a soloist can. So, while polyphonic synths excel at pads that fill the sonic spectrum, they can be less suited to leads that cut through that space.

I used to play bass in an R&B band, and figuring out where I sat in the mix with our keyboardist was a constant struggle. He liked to play a lot of chords with an anchor in the low end, and the bass would get lost at times. I would counter by adding fuzz or a synth pedal, but the added harmonics could crowd out our guitarist. (Our singer, meanwhile, continued to do what he did, blissfully unaware of the ongoing war for the mid-low frequencies. Ah, the life of a singer.) So my point is that there are times when filling space is useful. But there are also times when it is decidedly not.

The style of play also matters. The limitation of one voice becomes an advantage when you consider things like legato passages, where you want to smoothly glide from note to note. The same can be true of staccato passages, where too many voices at once can sound busy and confused.

More is often better, but there's a reason I'm perfectly happy with two legs instead of three. So, it really does come down to context. Every lock has a key, and sometimes a polyphonic key is the wrong fit for that particular musical lock.

Music has a lot of locks, so to speak, so sometimes the answer is a skeleton key, like ZOIA. A ZOIA patch can be a monophonic synth, a polyphonic synth, or even a combination.

Over MIDI, ZOIA can be a versatile polysynth. For example, the MIDI note in module supports up to eight notes at a time, each with its own pitch, gate, and, optionally, velocity output. However, it should be noted that while it is possible to make a patch that utilizes all eight of these outputs, there is often a compromise between the number of voices and their complexity.

If you want to use FM, for instance, then the number of oscillators you need doubles (or more), or if you're going to employ ZOIA's effects, each of these additions may mean compromising on the number of voices at your disposal. On the other hand, if you are designing a monophonic patch, you may run out of ideas long before you run out of CPU.

When used as a guitar synth or employing the CV inputs of Euroburo to control a synth, it may seem like you are limited to monophony. After all, the pitch detection on ZOIA is monophonic; there are only so many CV inputs to utilize. But suppose you use triggers, rather than gates, to control the envelopes of your voices. In that case, you can trigger overlapping voices to play simultaneously, much like how Mutable Instruments' Rings employs polyphony.

Of course, ZOIA has many internal methods of producing sound, from sequencers to generative approaches, and these can also have monophonic or polyphonic applications. Moreover, these can be combined with the previous methods to create patches that are more than just monophonic or polyphonic; they are multi-timbral. (Multi-timbral is just synth-speak for producing two different types of sound at once, like clapping while you play the kazoo. Or, arguably, something more aurally pleasing than that.)

This isn't to say ZOIA is the best answer to our initial question. There are many options for synthesizers and synth pedals out there, and plenty of them do things that ZOIA can't. (I've opened up the enclosure before, and there is no fold-out keyboard tucked inside.) Variety is the spice of life. But it may be that ZOIA is an answer that you've overlooked and is more versatile than you first imagined.