Jul 012014

Xen-FMTS 2

An FM Synthesis VSTi for the Creation of Microtonal and Xenharmonic Music
Xen-FMTS 2 is a 4 Operator FM Synthesis VSTi with a specialized set of features for computer musicians interested in exploring the vast expressive possibilities of making music with alternative intonation systems. It is a freeware 32-bit plugin instrument for Windows that includes 115 patches, 55 microtunings and 56 partials files.

Microtuning Features
  • Internally loads and externally receives both MTS (MIDI Tuning Standard) Bulk Dump and Single Note Microtuning Files
  • Operator ratios can easily be set to values that are coincident with the microtuning being used, thereby producing intonation related sidebands in the timbre of the instrument
  • Microtonal pitch-bend ranges may be configured in cents, harmonics and superparticular ratios
  • Arbitrary microtonal pitch shifting makes it possible to easily pitch transpose the oscillators in both octave and non-octave increments
FM-RM Oscillator
  • 4 Operator FM Synthesis with Ring-Modulation
  • 57 Operator Algorithms
  • 11 different Operator Waveforms
  • Analog Pitch Drift Emulator
  • Transposition by cents offsets
  • Partials text files may be used to quantize the frequency ratios of the operators to user specified values
  • Velocity-to-Harmonics Modulation enables oscillators to dynamically sound harmonics of the fundamental pitch
  • Seven dedicated hybrid modulators for Operators A, B, C, D, Filters, Amplifier and Pitch
  • Each modulator includes an ADSR style envelope generator, and an LFO which can be switched to run at audio-rate
  • Each ADSR Envelope Generator features Per-Stage Keyboard Tracking
  • LFOs can either be synchronized to the host DAW tempo or set in Hertz. They include 24 Waveforms, a Slewer and can be switched to run at audio-rate
Filter Section
  • Pre-Filter Saturation Stage with 20 Saturation Types
  • Two Independent Filters with Six Filter Types: LP4, LP2, HPF, BPF, BRF, APF
  • One and Two Stage Filter Cascade
Performance ControlĀ 
  • Full controller MIDI Pitch Microtuning with MTS (MIDI Tuning Standard)
  • MTS Support for both Single Note and Bulk Dump
  • Loads MTS Microtuning Format Files Internally and Receives MTS Externally
  • Local (Per-Patch) and Global Microtuning (Static Microtuning for All Patches)
  • Microtunings can be loaded from any directory on hard drives or storage devices connected to the PC
  • 12 Note Polyphonic
  • Monophonic Legato Mode
  • Monophonic Portamento
  • Microtonal Pitch Bend
  • Vibrato
  • Effects include Chorus, Lowpass Filter Cascade (Warm Filter) with 6 dB to 48 dB per-octave filters and Stereo Ensemble

Download Xen-FMTS 2

Xen-FMTS 2 Development Notes:

This iteration of our popular Xenharmonic FMTS VSTi features many new and exciting enhancements over the original, some of which were suggested by our users and development group:

A common comment about version 1 was that the user interface was too large for small monitors and laptop screens. In response to this user feedback, the interface was completely redesigned making it much smaller than before, which is now at 943 x 652 pixels.

Among the many new features are the Modulators, which include an ADSR-style envelope generator, and an LFO which can be switched to run at audio-rate. There are seven of these dedicated hybrid modulators for Operators A, B, C, D, Filters, Amplifier and Pitch. With the LFOs running at audio-rate, the pitch is controlled by the MIDI-to-CV and the loaded MTS Microtuning file; transforming the LFO into a pitch-accurate microtonal-controlled oscillator, which is in turn capable of introducing microtuning related sideband spectra into the composite synthesizer signal.


In the instrument’s Performance Control section, numerous improvements have been made, which include new MIDI Pitch Bend modes that enable users to specify precise bend ranges in either Cents, Harmonics or Superparticular Ratios. A Chorus effect has also been added, as well as a more versatile LPF cascade on the Ensemble page (a kind of tone control, formerly called Warm Filter).

In the FM-RM Oscillator section of the synthesizer, randomization and reset features have been added to two of the partials selection pages, as well as the ability to either multiply or divide the pitch of an operator by the selected frequency ratio. The completely redesigned Iso-Index page now includes an Op Rotate feature for rerouting the frequency ratios to other operators.

The Pitch page of the FM-RM Oscillator now features Velocity-to-Harmonics Modulation, where playing force through MIDI velocity is able to break out harmonics of the fundamental pitch. Another very important enhancement in the Pitch section is the inclusion of a full-featured Pitch EG that shares many common features of the other Modulators.

This version of the instrument also features the same versatile filter section that is found in two of our other instruments: Ivor and XenFont.

Please feel free to share your comments, perceptions, experiences – and especially music made with this instrument – either in the comments of this post, or through email.
Music featuring the Xen-FMTS VSTi
Please note that Xen-Arts software never has been, and never will be, infected with computer viruses; this we promise. If your virus software ever indicates that our microtonal music software has a virus, this is what is known as a False Positive. Contacting the developer of your virus software to make them aware of the false positive is the best solution.
 Posted by at 2:22 am

  9 Responses to “Xen-FMTS 2”

  1. Sir,

    I downloaded FMTS. But don’t know how to install it.

    Could You give me a feedback?

    Kind Regards,

    Renato Ornaghi – Italy

    • Hi Renato,

      Apologies for the delay in reply.

      To install the plugin, extract the ZIP archive into the plugin directory that you use for other VST/i plugins. Then when you open your DAW, it will find it there. Sometimes it will be necessary to rescan the plugin directory with the DAW software you use, so it will find any new ones that have been added.

      One of the primary DAW hosts I use is REAPER. After extracting the ZIP archive into the VST/i plugin directory, it is possible to rescan that directory, then REAPER will find the new plugin, so that I can load it into a track.

      What DAW host program do you use?


  3. Any chance this will ever be ported to Mac OS X?

  4. Welcome Fred,

    It’s a frequently asked question, with a complicated answer.

    While there is reportedly some ongoing effort to make SynthEdit (the modular-synthesis environment within which all these instruments were built) cross-platform compatible for both PC and Mac, it is highly unlikely that it will ever manifest in the Xen-Arts instruments being available for Mac-based systems, due to that they all use proprietary and commercial 3rd party modules I either bought, or donated for, and all of the developers of these modules have now permanently left the scene. It’s also highly unlikely that the Xen-Arts instruments will ever be available in x64, although I’m using them all reliably with various kinds of bit-bridging applications.

    If, and when, a fully mature Mac version of SE does become available, it’s my hope, that at a minimum, the MTS functionality will be preserved, since this is one of the most powerful features of this program. Even without the proprietary modules used in the Xen-Arts line, being able to create any kind of MTS compatible virtual instruments for the Mac platform would be an epic breakthrough. Hopefully I won’t be a pensioner, or no longer alive, before this comes to fruition.

  5. Do any of your VSTI products offer the ability to send note frequency values instead of MIDI notes? I have a friend developing a software keyboard for microtonal experimentation/performance, and it already uses CSound for audio and doesn’t use MIDI at all. I couldn’t tell from a quick look whether the VSTi spec would allow for such an approach – seems like MIDI just gets in the way for something like this.


  6. Hi Chuck,

    Unfortunately no. All of the Xen-Arts instruments are MIDI driven and the intonation controlled by MTS.

    Although I wouldn’t be able to offer a solution, it might be possible to create some kind of device that could transmit MTS SYSEX to such an instrument in real-time; in particular MTS Single Notes Dump (Scala Tuning Model 1).

    There’s so much power a possibility with MTS. It’s a shame that it’s not caught on, because it would be the ultimate and most viable for real-time microtuning.

  7. i downloaded the xen fmts folder but i can’t find a zip file to extract

  8. Welcome Jack,

    Check out the installation notes on this page:


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