As the scl/tun dust settles...

Folks,

While it looks like some of the discussion revolved around some misunderstandings, we are still very much in a state of flux WRT support for a common, useable microtonal tuning format. Since it won't settle for some time (if ever!), it is good to mull over all aspects, pros, and cons.

I saved something last fall by my good friend Jacky Ligon, and am posting it here for thought. As always, it is just one opinion, but a reasoned one. I don't have the time to get involved in the discussion, but possibly some might find it usefull...

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Microtuning Soft-Synths - The Case for the TUN Microtuning Format
Jacky Ligon

With the rapid advances in the development of soft-synthesis, it is indeed a great and excitingly unprecedented time for the electronic sound explorer to investigate the sonic delights of microtuning.

Perhaps never before in the history of 'specific-pitch' intonation systems, have musicians had such a golden opportunity to make music with these microtunings, and to be able to do it with the very fine precision that one has available in today's software-synthesizers.

The whole exciting history of intonation, as well as an empowering and never-before-heard 'future music' becomes available to the musician and composer with these new tools.

At this early and formative stage in the development of microtunable soft-synthesizers, we may observe a few interesting developments and trends amongst the various software developers with regard to providing microtuning functionality:

1. The use of microtunings which only allow the user to retune 12 pitches within a fixed 2/1 octave.

Synapse Audio, developers of the fine Orion Platinum VSTi/DXi (Virtual Studio Technology Instruments/Direct-X Instruments) host, have opted to implement 12-Pitch Octave Microtuning in Orion using the Scala native SCL format.

2. MPBM - Midi Pitch-Bend Microtuning .

Synthesizers without any ability to use microtuning table formats, can often be retuned in real-time with midi pitch-bends, using 'relay' software for this purpose. Scala and Fractal Tune Smithy provide MPBM capabilities with midi-relay functionality.

3. MTS (Midi Tuning Standard).

MTS has been implemented in the Native Instruments FM7, a quite fine FM-synthesis plugin.

4. Scala SCL.

RGC:Audio, developers of the Z3TA+ software-synthesizer have opted to implement microtuning functionality using the Scala SCL format, which in this case enables full arbitrary retuning.

5. TUN.

The TUN microtuning format has been implemented by Software Technology in the VAZ line, by Big Tick in the Rhino, Angelina and Rainbow synthesizers, by LinPlug in the CronoX soft-synth, and in the Anamark VSTi.

6. Support of multiple microtuning formats in software synthesizers.

The TobyBear Helios VSTi has the very interesting capability of working with both TUN and SCL.

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Let's examine these various microtuning formats from the musician's standpoint, for their strengths and weaknesses:

1. Microtuning restricted to only a 12 pitch set with a fixed 2/1 octave.

This represents possibly the most constraining and musically limiting scenario of all the above. At first a beginner might find it useful for some kinds of tunings, and truthfully this kind of tuning implementation can be useful at the beginning of exploring microtonality, but very quickly the musician will wish for the capability to retune the instrument to any desired pitches, but will be confounded in doing so because this kind of paradigm will not allow one to work with microtunings which may have less, or more than 12 pitches to the fixed 2/1 octave. Obviously exploring microtunings with a stretched or compressed octave would be out of the question with this kind of implementation.

2. Midi Pitch-Bend Microtuning.

MPBM can be quite powerful and useful for basic microtuning and playback of General Midi (GM) midi-files. To use MPBM, one must set up the synthesizer to play the same sound on a number of midi-channels (determined by how many notes one wishes to play polyphonically).

This is easier to do with a dedicated hardware or sound-card synthesizer, whereas trying to do this kind of microtuning can be quite challenging on the CPU requirements of a basic computer system.

One severe drawback to MPBM is that strange sounding artifacts can be introduced into the music if the sustain-stage of the synth sounds are set too long, because as the midi-relay software cycles quickly between the different midi-channels to play the required pitches, one will invariably detect subtle glissandi-like effects in the sustain-stage of the sounds, which can often obscure the subtle nuances of microtuned music.

3. MTS.

MTS has many powerful possibilities, amongst them the capability of sending tuning data to a soft-synth in real-time, however, as of this writing, there exists no instrument hosts which have the functionality of sending MTS to a soft-synth, which makes this a very curious choice of microtuning implementation for the NI FM7. Perhaps developments in host software will make MTS a more viable possibility, but as it stands, this isn't an optimal, practical or even functional way to microtune soft-synths.

4. Scala SCL. The Scala SCL format is commonly used as a way to create, store and analyze microtunings. In the case of using hardware synthesizers with microtuning functionality, one may use the Scala program to convert an SCL file into SYSX data, and send this via midi to the instrument. For soft-synths, Scala can create SCL, TUN and MTS format microtuning files for the instruments. One important drawback of choosing to implement the SCL format in a microtunable soft-synth, is that the SCL format itself does not contain data for tuning the base frequency of a microtuning. In the case of the fine RGC:Audio Z3TA+ soft-synth, to set the root frequency of a microtuning, one must use the global tuning page to set the root for every patch that shares a common tuning within a given composition.

5. TUN.

The TUN microtuning format enables one work with full arbitrary microtuning, and be able to specify the root frequency and middle midi key for the microtuning in use, all within the tuning file itself.

Every key across the midi range is instantly retuned to the desired pitches, and in this scenario it is unnecessary to have to change any global settings for the oscillators in order to make the tuning play in the correct root frequency. Currently there are two applications which can create the TUN microtuning format - Scala (for PC, MAC and Linux), and LMSO (MAC). A recent development in this format has been the implementation of an 'enhanced' TUN format, where microtunings may be specified with an unprecedented six decimal places of accuracy (in cents)!

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Considering the possibilities available to the electronic musician seeking to empower their music with the sounds and capabilities offered by instruments which have implementation of full arbitrary tuning (FAT), it would appear that currently the best two options are the Scala SCL and TUN formats.

When the choice is made to implement microtuning functionality using the SCL format, it becomes necessary to provide the user with some easy way to set the root frequency, and the middle key (the physical key which the tuning begins on) of the microtuning. Perhaps ideally, this could be achieved by being able to type in the desired pitch (in Hz), and with the middle key, a drop-down list or something of the like. Since the Scala SCL format doesn't contain data for telling the soft-synth what to do with regard to the root frequency and middle key, the ability for the user to specify these settings within the synth itself becomes a crucial matter with regard to being able to map any desired pitches, to any desired or required configuration of physical keys on a midi-keyboard or other controller.

However, with the TUN format, all of the settings for the full-keyboard microtuning, root-frequency and middle-key are fully configurable within one simple text file, which the soft-synth can open, obviating any need to make other settings within the synthesizer with regard to the root-frequency and middle-key.

Hopefully this short examination of some of the currently available microtuning formats for software-synthesizers will have made a powerful case for developers to consider implementing a minimum of the TUN format for their virtual instruments. The capability for the musician to be able to fully retune every pitch across to range to any desired specific-pitch intonation system, and be able to easily set root-frequencies and middle-keys for mapping the microtunings to the midi-controllers of their choice, is simply one of the most powerful tools currently available in electronic music today.

Jacky Ligon 09/09/03

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Scala
http://www.xs4all.nl/~huygensf/scala/

LMSO
http://www.nonoctave.com/tuning/LilMissScaleOven/

Synapse Audio
http://www.synapse-audio.com/

Fractal Tune Smithy
http://tunesmithy.co.uk/

Native Instruments
http://www.native-instruments.com/

RGC:Audio
http://www.rgcaudio.com/

Software-Technology
http://www.software-technology.com/

Big Tick
http://bigtick.pastnotecut.org/index.php

LinPlug
http://www.linplug.com/

Anamark
http://www.anamark.de/