Jan 022011
Xenharmonic FMTS 
An FM Synthesis VSTi For The Creation Of Microtonal and Xenharmonic Music
Xenharmonic FMTS is a 4 Operator FM Synthesis VSTi with a specialized set of features for musicians interested in exploring the expressive possibilities of microtonal and xenharmonic music making.

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 tuning related FM sidebands in the timbre of the instrument.
  • Isoharmonic spacing of the operator ratios.
  • Precise values may be set for microtonal pitch-bends.
  • Arbitrary microtonal period shifting makes it possible to pitch transpose in both octave and non-octave increments.

FM-RM Oscillator

  • 4 Operator FM Synthesis with Ring-Modulation.
  • 57 Operator Algorithms.
  • 11 different Operator Waveforms.

Phase & Pulse-Width Oscillator

  • 22 Waveforms.
  • Phase & Pulse-Width LFO Modulation.

Envelope Generators

  • 6 independent Envelope Generators dedicated to modulating Operators A-D, Filters and VCA.
  • Velocity sensitive.
  • Keyboard tracking.


  • 2 State Variable Filters with 12 and 24 dB response.
  • Cutoff frequencies modulated by Velocity, Envelope Generator, LFO and Keyboard Tracking.
  • Low Frequency Oscillators can be set to modulate the cutoff frequencies of the filters at audio rates, thereby producing sidebands in the signal.


  • Saturator for subtle to extreme distortion.

  • 6 dB LPF Warm Filter.
  • 4-Voice Stereo Ensemble Detuner. 

This VSTi is a gift to the xenharmonic and microtonal community, as well as to musicians and composers who are interested in exploring the exciting possibilities of microtuning in their music. It is being offered as freeware and can be downloaded here:

 Posted by at 5:16 pm

  25 Responses to “New Release: Xenharmonic FMTS VSTi”

  1. Thank you very much for making this very useful tool available. I’m sure it will be taking me into some new areas this year, beautifully designed, very intuitive…love it already! Cheers.

  2. THIS is a pleasure to dig into. I do not know much about the mechanics of Microtonal sound, but I know a small bit about FM. This synth goes deeeep. Anyway, it doesn’t matter because I’ve still managed to sit here for over an hour now tweaking this thing in crazy useable/unusable knots. Thank you so much for this thoughtful gift. Thanks to ALL the developers who had a hand in it and thank you for the fantastic manual as well. Cheers

  3. Hi djemptyx,

    Very glad to hear that you are enjoying working with the synth. Let me know if you use it in your music – I’d really love to check out anything you have to offer.

  4. Nice, will do Jacky. Btw, I am noticing that there are not many parameters that are available for the “Configure” option when one would like to use MIDI automation in Ableton Live 8. I will copy a portion of text from the Ableton Community forums that could help in your next update. I don’t know because I have no idea how to program. Here is the text: “- It is essential for the plugins to correctly support parameter gestures (BeginEdit, EndEdit for VST) according to the plugin standards to let the configure modus work. If you find a plugin not working with configure mode in Live, please report to the plugin developer.”

    Can you make sense of it? Thanks for any help!

  5. Hi djemptyx,

    It is possible to expose more automation parameters to the host DAW than are currently available. This is something that I could do in the next incremental update. Perhaps we can have a more detailed discussion in a dedicated thread.

    Worth mentioning though, is that pretty much all of the synth’s parameters can be automated/mapped to any MIDI continuous controllers desired, by right-clicking on the control, choosing Learn, then sending the CC (detailed in the manual BTW). It is also possible for those CCs to come from track automation within the host, but it will be a matter of figuring out how to route them in Ableton.

    In REAPER for instance, I can send track automation to any parameter with the Learn feature. Also, I use a MIDI LFO in my music, which I can route to the synths from its own track.

    I would like to understand if these kinds of routing options are not possible in Ableton Live though, and then we could discuss what does need to be exposed to the host and I could do this for our next update.

    Later today I’ll begin a new post seeking everyone’s input on the automation question.

  6. Hi Jacky,

    Great to find you still creating and thriving – quite an interesting looking plug-in there.



  7. sounds good and look good but i will not use it very much because the gui is way to big for me…

  8. Hello,

    Your download link is no longer active, something about your file having violated the TOS of Megaupload.com. Do you have an alternate download location?

  9. Hi Anonymous ,

    This past week I noticed that it appeared the Xen-FMTS file had been deleted but I couldn’t figure out why since everything on both this site and MU is 100% legit and legal. Anyhow, I’ve re-uploaded the file just now. Let me know if you have any further problems.

    I wonder if it might be because of the number of downloads. Before I noticed the file was gone, the stats showed about that the synth had been downloaded about 4,000 times. It has been quite popular. 🙂



  10. The DL link appears to be dead again. I’ve read good things about the synth and would like to review it and make a vid. Would be happy to host it as well on my site http://www.loopartists.com/free-vst.php

  11. hi timbreman,

    Apparently the recent system updates that Google/Blogger have made make it impossible for me to use my regular browser to post replies to comments on this blog, so this morning I’m trying Firefox, which appears to allow me to post anonymously here. Sorry for the slow reply.

    Please try the download link again if you have not already. When I checked it after receiving your message, it was working properly. Thanks very much for the offer of review and video – I’ll be very eager to see what you have to share about the instrument.

    There are some other microtonal tools in progress, and I’m working on these as time allows along with other music commitments.



  12. Hi/bonjour,

    First, thanks for your synth!
    I like it clear sound with subtle, weird but controlled modulations. Nice work.
    In my host, Usine, i can’t access to parameter automation by midi control change, yet… Maybe make those parameters visibles from the host in a next version?

    Salutations, Cyrille.

  13. Hi Cyrille,

    Thanks very much for the feedback.

    Yes – the plan is to expose more modulation targets to the host with the next update, which will have other significant enhancements as well.

    In this thread we have been discussing the evolution of the next version of Xen-FMTS:


    Feel free to let us know what you would like to see.


  14. I have been able to get this running on a Mac (OS 10.6.7) using only the free emulator Wine + a free simple VST host. Finally, the world is mine!

  15. Hi Jacob,

    I’m completely amazed and thrilled that you’ve got it working on the Mac – bravo!

    Please let me know how you get on with the synth and I’d especially be interested in hearing any music you create with it.



  16. Looks interesting. But why no support for Scala .scl (or .tun) files? Those are pretty standard in software synths. I’ve been doing microtonal music off and on for years, and I have yet to use a MIDI tuning dump.

    –Jim Aikin

  17. Hi Jim,

    Thanks for dropping by.

    While I also use VSTi that work with SCL (such as Pianoteq) and many that use TUN (Albino, Alchemy, VAZ Modular, etc.), there are some distinct advantages to MTS, such as the ability to retune entire ensembles of MTS-enabled VSTi from a single track in a DAW, whereas with these other formats, musicians must open each VSTi one-at-a-time and manually load different microtunings. If more soft-synths used MTS, it could massively streamline the whole process of working with microtunings in computer music, because all of the tuning in a composition could be centrally controlled for all instruments. The unfortunate thing is that so few VSTi support MTS although the plan is to release more tools here that use it.

    One issue with SCL is that any implementation of it must include the use of the KBM (keyboard mapping) files. Otherwise microtunings are always mapped with the reference frequency and 1/1 on middle C-60. Some devs have got it right, such as Modartt Pianoteq, while Cakewalk, as far as I know, did not implement the use of KBM files in their Rapture and Dimension VSTi. This should really not to be regarded as full-keyboard microtuning functionality, but some extremely crippled version of it, and for all practical purposes the Cakewalk implementation of SCL is useless for any serious work with alternative intonations. There is a new version of Z3TA out now though, and I’m unsure about whether or not it supports KBM.

    I suppose one advantage of TUN/SCL/KBM over MTS is that these formats are human-readable, but as far as the ability to retune instruments in real-time, MTS is still the best option we have. It’s a strange twist of fate that it has rarely been implemented in software synths, being that it’s been a part of the MIDI standard for so long.

    I do agree though that the introduction of more formats is a big and troubling question in the development of new microtonal softsynths. If it weren’t that MTS has been around for so long, then it might have been out of the question for Xen-FMTS and all that will follow. I suppose like lots of other xen-micro musicians, I’ve had to resign myself to a future of microtuning format diversity, although I personally see MTS as a badly needed evolution for the future of microtonal software synthesis.

    BTW – Having you drop by here makes me recall an article you wrote about 19 ED2 in Keyboard Magazine – if memory serves – sometime back I the late 1980s. So I’ve been aware of you and your interest in microtones for quite some time now. Write sometime if you like, and if you have a chance to check out Xen-FMTS I’d love to hear what you think.

    Kind Regards,


  18. I’d love to try it… first heard of your work from Jeff Scott. The download link seems to be not working again.

  19. Hi Anonymous,

    Thanks for dropping by. Give it another try now; I just checked the link and it seems to be working. Might’ve been a temporary problem with MU.

    Let me know how you get on with it and please feel free to share any tunes you make.


  20. not work in winxp sp3 in aodix / rax n trax /savihost

    not work both versions of Xenharmonic FMTS VSTi 1.0 and 1.1 –

    screen shots of error


  21. Hi beebka,

    Very sorry you are having these troubles. Our beta testing group was testing primarily with DAWs: Reaper, Cubase and Ableton Live. I found out a few days ago that Xen-FMTS also works well in Sonar. I will keep your bug reports for the next update cycle. Thanks for letting us know. My main regret is that you will be unable to check out the synth, but if you want to hear it, please try it in Reaper and see how it goes. I’m also on XP Pro SP3 here – BTW.



  22. FWIW I have it working on (the evil) Vista 64 and Sonar X1.

    I’ll probably try it with Win 7 64 later today.

  23. Hi Chris,

    Thanks for letting us know about your success with running the synth in Sonar and on these 64 bit OS. This is what I was referring to above in the reply to beebka.

    FYI and FWIW – It appears that the Xen-FMTS VSTi, and future Xen-Arts microtonal synthesis tools as well, will remain at 32 bit for quite some time.

  24. I would love to try it, but every time I click on the download link on 4shared, nothing happens. I have tried over 10 times.

  25. Hi Anonymous,

    Sorry for the dl hassles. I might suggest checking to insure that you have javascript activated in your browser. This would certainly prevent dl’ing from 4shared, as their site is pretty thick with js.

    If you can’t get it to work, you can email me privately, and I’ll be happy to email the ZIP archive to you. Just let me know.

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