Practice and theory in 13-tET -- Hi, Mary

Hello, there, Mary, and thank you for your friendly response and
questions.

One thing I would say about 13-tET, which I suspect would also apply
to the almost identical scale you can get by dividing Phi into nine
equal parts and carrying the tuning to 13 steps (as John Chowning did
20 years ago in a composition named _Stria_), is that timbres can make
an immense difference. The effect can be one of a "misty" and
impressionistic consonance, or of tense dissonance; the timbre I'm
using leans toward the first kind of effect.

Anyway, as you suggest, we Phi-lovers may form a special category in
the xenharmonic community. Two of my favorite 24-note tunings based on
Pythagorean have intervals quite close to Phi, and the 13-tET
approximation of 9/13 octave is very close to a JI ratio of 21:13.
At least in a reasonably gentle timbre, Phi has a kind of mysterious
or foggy kind of relative concord -- a bit Debussyan, I might say.

Now for your MIDI question, to which my answer might seem a bit
"medievalistic," especially for someone like you who's doing
state-of-the-art audio production:

> Also thank you for diagramming out how you are using two keyboards.
> Do you play them together, or sequence them separately and then
> combine into one file?

Here I should explain that I have the two keyboards connected to the
synthesizer through a "MIDI merger" box, and typically play them
together, much like a conventional two-manual organ. However, they
aren't connected to any device or interface for recording or playing
MIDI files.

Your question suggests to me that there might be different approaches
for recording MIDI files using two or more keyboards, each with its
own advantages, and this could be a really interesting topic.

For example, I've heard about a 72-tET setup with six 12-note
keyboards for the complete tuning, and I'm not sure if people have
recorded MIDI files with this type of arrangement.

Maybe I should explain how I go about composing something and sharing
a MIDI file of it here.

First, typically, I try ideas out at the keyboard, come up with
something I like, and write it down in some notation -- basically,
maybe not too different from composing at a traditional organ or
harpsichord.

Then, at the computer keyboard, I use a text editor to write a Scala
MIDI example file with instructions defining the tuning to use, the
notes and durations in each part, and the General MIDI timbre. It's
rather like programming in some very user-friendly computer language.
Then I use Scala to translate this text file into a MIDI file with
pitchbend messages for the given tuning.

One of the problems of this approach for something like 13-tET is that
the effects are very highly timbre-sensitive. A piece using the
interval of 8/13 octave or about 738 cents as a consonant fifth in the
right synthesizer timbre might sound quite "strange" in a typical
General MIDI timbre.

Recently the tuning/timbre equation has been a big theme in TMA, and
I'm really impressed with the possibilities here, not least in your
music.

Peace and love,

Margo