Hi Shakuman and others,
Microtuning is possible with VSL, but you will need a specific setup.
1. First of all you'll have to use a sequencer with a "modular" approach: Tracktion and EnergyXT (the cost of this program is a no brainer, plus: it acts also as a plugin itself with its special VST-version, not AU btw) will do the job, or a decent VST-host like Cantabile, which is an outstanding piece of software anyway. Most sequencers or hosts like Vienna Ensemble (PRO) can't do this, because there isn't any possibility to manipulate the MIDI signal before it gets into an instrument like Vienna (or whatever synth you like): there is ususally only a routing involved between the MIDI instrument and the audio output (a..o. Sonar has some MFX though).
2. Then download the Midibag made by 'Toby Bear' (freeware). You will find here a set of very useful miditools (amongst them a nice humanizing tool). What you need here is of course the MicroTuner. Just put this into you VST folder and install the two 'registry installers' (it's safe). This MicroTuner tool needs specific tuning files. You can make them yourself, using Scala software, this is a freeware tool BTW (see for further instructions on this website). If this is too much trouble download here a huge set of tuning models, I can't remember where I downloaded it myself so I just uploaded this folder to my own server for you.
3. Open one of the programs mentioned under 1. For example in EnergyXT the setup would be as follows. Midi In > MicroTuner (load the tuning file of your choice) > Vienna Instrument (in which of course the Pitch is correlated to the pitchwheel, so make sure that you have done this in the performance window) > Audio Out.
In Tracktion and Cantabile put the Midi manipulating tool (MicroTuner in this case) of course before the synth/instrument, and the result will be the same.
If you have some spare time left I advise everyone to experiment also with the Humanizer tool form this Midibag. It will randomize timing, pitch and CC1 for example. With a CC router plugin you will be able to randomize with customized ranges every parameter you have setup in your Vienna Instrument. Also on ThePiz there are interesting free plugins (a.o. a X-Y CC controller, nice for cell combining patches in VI), but again: you will need the software like I mentioned hereabove, with the same kind of setup.
Personally I use the Humanizer tool also sometimes with an EQ-plugin that has a MIDI learn function, so with this you can even randomize the color of the sound as much as you want yourself, just like a real musician would or must do in real life. But this issue is not so much at stake here.
I hope that this little piece of information will help you out for the moment concerning the microtuning issue.If you need a quartertone instrument with 24 intervals per octave I would suggest using two patches with different quartertone settings. As simple as that.
Perhaps this thread could be renamed now in 'Microtuning possible however!' 😊
Please let me know if you need more assistance in this anyway.
regards,
Erik