I thought I knew what a modular synth was from my days in the Moog lab at school, but now all kinds of software synths call themselves modular — what does it really mean?
SOS contributor Len Sasso replies: The term modular does have a great deal of buzz value these days, which is why many stand-alone and plug-in software synthesizer designers are jumping on the bandwagon. While it seems unreasonable to insist that a software modular be a direct emulation of a classic modular synth, there are two basic criteria for distinguishing synths which are in the spirit of the classic hardware modulars.
One criterion is the routing flexibility of the audio and control signal paths — the whole concept of distinguishing audio from control signals may seem unnecessary in software, but it's actually quite useful. Control signals can be sampled at a much lower rate — thereby using less CPU power — and still do their job.
The other criterion is that there be modules of roughly the same function as in the hardware modulars. If the modules are too atomised, as in applications like Reaktor, Infinity or Max, you have more of a graphic computer language for constructing synths rather than a modular synth. At the other end, if the modules are full-on synths as in products like Reason and Storm, you have a rack of synths, not one modular synth.
In a modular synth, the modules have a specific function — oscillator, filter, envelope, LFO, and so on — and have their own control panel for setting them up. Furthermore, there has to be a sufficient variety of modules of each type to allow for interesting combinations.
What constitutes a sufficiently flexible routing scheme is a little more fluid. Certainly the use of virtual patch cords is not a requirement (though that can be fun). Many classic hardware modulars relied on a patching matrix rather than patch cords. It seems reasonable to require that in one way or another, most audio outputs can be routed to most audio inputs, that most audio outputs can be also used as modulation sources, and that most control outputs can be routed to most control inputs. In short, you shouldn't quickly run out of ways to reconfigure the system and have to rely mainly on different control settings to produce different sounds.
Software and hybrid synths that seem to me to fit that bill include Arturia's Modular System, Clavia's Nord Modular, Software Technology's VAZ and Virsyn's Tera.