Editing Frequency modulation synthesis (section)

==== Additional improvements: Variable Phase Modulation, FM-X Synthesis, Altered FM, etc. ====
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In 2016, [[Korg]] released the Korg Volca FM, a, 3-voice, 6 operators FM iteration of the Korg [[Volca]] series of compact, affordable desktop modules.<ref>[https://www.korg.com/us/products/dj/volca_fm/ Volca FM product page]</ref> Korg has also released the [https://www.korg.com/us/products/synthesizers/opsix/ opsix] (2020) and opsix SE (2023), integrating 6 operators FM synthesis with subtractive, analogue modeling, additive, semi-modular and Waveshaping.

Yamaha released the [[List of Yamaha products#Synthesizers|Montage]] in 2016, which combines a 128-voice sample-based engine with a 128-voice FM engine. This iteration of FM is called FM-X, and features 8 operators; each operator has a choice of several basic wave forms, but each wave form has several parameters to adjust its spectrum.<ref>[https://usa.yamaha.com/products/music_production/synthesizers/montage/features.html#product-tabs Yamaha Montage Product Features Page]</ref> It was then followed by the more affordable Yamaha [[List of Yamaha products#Synthesizers|MODX]] in 2018, with 64-voice, 8 operators FM-X architecture in addition to a 128-voice sample-based engine.<ref>[https://usa.yamaha.com/products/music_production/synthesizers/modx/features.html#product-tabs Yamaha MODX Product Features Page]</ref> The MODX+ released in 2022 increased the number of voices of the FM-X engine to 128, the same as with the Montage.<ref>[https://usa.yamaha.com/products/music_production/synthesizers/modxplus/features.html#product-tabs MODX8+, MODX7+, and MODX6+ Features]</ref> The Montage was succeeded by the Montage M in 2023, which uses the same 128-voice, 8 operators FM-X engine alongside a 128-voice sample-based engine and a newly-introduced 16-voice 3 oscillator analog-based engine known as AN-X.<ref>[https://usa.yamaha.com/products/music_production/synthesizers/montagem/index.html#d2153572 MONTAGE M Synthesizer]</ref>

Elektron launched the [[Elektron (company)#Music Hardware|Digitone]] in 2018, which is an 8-voice, 4 operators FM synth featuring Elektron's renowned sequence engine.<ref>[https://www.elektron.se/products/digitone/ Digitone product page]</ref>

FM-X synthesis was first introduced with the [[List of Yamaha products#Synthesizers|Yamaha Montage]] synthesizers in 2016. FM-X uses 8 operators. Each FM-X operator has a set of multi-spectral wave forms to choose from, which means each FM-X operator can be equivalent to a stack of 3 or 4 DX7 FM operators. The list of selectable wave forms includes sine waves, the All1 and All2 wave forms, the Odd1 and Odd2 wave forms, and the Res1 and Res2 wave forms. The sine wave selection works the same as the DX7 wave forms. The All1 and All2 wave forms are a saw-tooth wave form. The Odd1 and Odd2 wave forms are pulse or square waves. These two types of wave forms can be used to model the basic harmonic peaks in the bottom of the harmonic spectrum of most instruments.  The Res1 and Res2 wave forms move the spectral peak to a specific harmonic and can be used to model either triangular or rounded groups of harmonics further up in the spectrum of an instrument. Combining an All1 or Odd1 wave form with multiple Res1 (or Res2) wave forms (and adjusting their amplitudes) can model the harmonic spectrum of an instrument or sound.<ref name="zollinger2016">{{Cite web|url=http://javelinart.com/FM_Synthesis_of_Real_Instruments.pdf |archive-url=https://web.archive.org/web/20170925230705/http://javelinart.com/FM_Synthesis_of_Real_Instruments.pdf |archive-date=2017-09-25 |url-status=live|title=FM_Synthesis_of_Real_Instruments|last=Zollinger|first=W. Thor|date=Dec 2017}}</ref>  {{citation needed|date=August 2017}}

Combining sets of 8 FM operators with multi-spectral wave forms was first introduced in the FS1R, released in 1999 by Yamaha. It was able to achieve similar results to that of FM-X using 8 noise operators.