Taylor Livingston
Commercial User
The Dubterranea/Xerograph combo and the FMeron represent different methods of synthesis.
FMeron implements frequency modulation synthesis. Most people think of the Yamaha DX7 and other keyboards from this family when FM is discussed, although technically those are all phase modulation synths and the FMeron is not specifically inspired by those keyboards or necessarily attempting to emulate them. It's really more inspired by modular synth dual oscillators like the Harvestman Hertz Donut and Buchla 158. These are tactile, playable, and to me very inspiring music tools that invite creativity, which were some of the main goals with the design of the FMeron.
So the version of FM synthesis in the FMeron starts with sine waves, which naturally have no harmonics, and by modulating the frequency of one with the other, all kinds of strange new harmonic sounds are generated. No filter is needed with FM, although you can definitely extend the palette of the FMeron by combining it with a filter like the Xerograph Deluxe. To my ears, FM is more "futuristic" sounding, or maybe retro-futuristic. It can be both harmonic and inharmonic, and very distinctive or it can just do a very pure octave down sine wave if that's how you set it.
The Dubterranea/Xerograph Deluxe combo are all about subtractive synthesis, which is kind of a backwards approach: start with a very buzzy, harmonically rich waveform, and then selectively remove some frequencies and accentuate others with a resonant filter to create new timbres. This type of synthesis is commonly associated with Moog, among others, and is probably a more recognizable, "classic" sound that you'll hear in lots of hit records from the last 5 decades. The typical subtractive synthesizer has one or more oscillators, a filter, and a voltage-controlled amplifier (VCA) that gives the sound dynamics (otherwise the oscillator will sound constantly, even when you aren't pressing a key). The Dubterranea isn't an all-in-one synthesizer - it contains multiple oscillators and the VCA, as well as all the stuff involved in tracking the pitch and dynamics of what you play to control the oscillators and VCA. So you need to pair it with a filter to get the full subtractive synth sound.
Both pedals can do octave up or octave down, but FMeron can only do one at a time. Dubterranea can have octave down, unison, and octave up all simultaneously, so three stacked octaves plus the clean signal.
