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Writer's pictureArch Delaro

Perfectly Tuned FM Synthesis with Thru-Zero

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Searching for a way to achieve perfectly in-tune music with frequency modulation (FM)? Look no further! Thru-zero frequency modulation (TZFM) offers a unique and captivating approach to modulating oscillator frequencies, ensuring your sounds remain perfectly in tune, regardless of modulation depth.


Let's dive into the fascinating world of thru-zero FM synthesis and explore the differences it brings compared to linear and exponential frequency modulation.


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The Limitations of Traditional FM

Imagine patching one oscillator's output (the modulator) to another oscillator's frequency control voltage input (the carrier). With linear or exponential FM, when the modulator's waveform rises above zero volts, it adds to the carrier's pitch control voltage, causing an increase in pitch. Conversely, when the modulator's waveform goes below zero, it subtracts from the pitch control voltage, resulting in a decrease in pitch.


This traditional method of FM synthesis can lead to confusion and frustration when it comes to creating melodies that stay in tune. The modulation often results in pitches that drift, making it difficult to maintain musical coherence.


If you feel adventurous and want to tame the beast that is FM to create great melodies, we have a series of patch notes that cover a vast array of FM possibilities.


Here's an example:


Patch note

The Magic of Thru-Zero FM Synthesis

Thru-zero FM offers a groundbreaking solution to the aforementioned problem. Unlike typical oscillators that only respond to positive control voltages, certain special oscillators can handle negative FM control voltages, allowing for the generation of inverted waveforms. These special oscillators achieve this through a TZFM input.


By using thru-zero FM, you unlock a new world of captivating sonic possibilities. This remarkable characteristic ensures your music stays perfectly on pitch, no matter the modulation depth. Thru-zero FM essentially allows the carrier oscillator's frequency to cross through zero Hz and into negative frequency territory, which maintains the overall pitch stability.


Digital oscillators excel at implementing thru-zero FM due to their inherent flexibility and precision. However, analog oscillators are quickly catching up, with an increasing number of modules now supporting this powerful feature.


Seven Outstanding TZFM Oscillators

Several noteworthy Eurorack modules embrace thru-zero FM, expanding your sonic horizons. Here are a few that showcase the versatility of this technique, covering a wide price range from $119 USD to $779 USD:



These modules demonstrate the versatility and potential of thru-zero FM, offering musicians tools to create precise and innovative soundscapes.


ALGO by RYK Modular

ALGO is a new module that excels at tackling FM synthesis. For those looking to dive even deeper into the world of FM synthesis with an extreme simplicity, this module by RYK Modular provides an exceptional platform. Learn more about how ALGO can transform your music by reading our detailed article.


Conclusion

Thru-zero frequency modulation offers a compelling solution to achieve perfectly in-tune music with FM synthesis. By utilizing this unique approach, TZFM ensures that oscillator frequencies remain stable, regardless of modulation depth. This opens up a world of captivating sonic possibilities and eliminates the frustration of creating melodies that drift out of tune.


With an increasing number of modules supporting thru-zero FM, musicians can explore this powerful feature regardless of their budget. Dive into the world of TZFM and elevate your music to new heights of creativity and precision.

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