Xx Tutorial 3: Using the Canon Tool By Len Sasso and Eric Wenger
Xx provides interactive tools for composing Canons. A Canon consists of several voices playing the same theme which is offset in time and in pitch. Typically, the first voice enters at the fundamental, and the second voice enters a fifth or an octave higher and a half or whole measure later.
In our example, we are going to compose a canon starting with two voices and ending with three.
Step 1: Set up the scale, instruments and tempo.
XX provides key and mode constraints for entering and manipulating
notes. So, before we start, we need to decide upon a key. Use
the Mode menu to choose the MinorNatural scale in the key of E.
Set the tempo to 88 BPM.
For generalizability, we have used the Beatnik software synthesizer General MIDI instrument. If you have better sounding MIDI instruments, please select the corresponding devices and program changes in the Track Set-up dialog.
The layout should be as follows:
Step 2: Set up the Canon tools
The time offset (delay between each voice) is set to 480 which
corresponds to a half note at 240 ticks per quarter. The dialog
should look like the following picture:
The "avoid dissonances" check box is turned off to prevent Xx
from automatically “fixing” notes.
In the main window, turn on the Display Octaves toggle so you can see the piece's notes 'shadowed' in each octave. This makes detection of dissonance easier.
The grid is set to 120 (i.e. 8th notes).
Now we are ready to start.
Step 3: Composing section A
The first part will be a slow movement using only two voices,
tracks 1 and 2.
We will start the piece with the fundamental, E. Click and drag
on the E3 line to enter a whole note. Observe how notes on track
2 are automatically echoed with the proper pitch shift and time
delay.
In the provided example, I started with whole notes (960 ticks) up until measure 5 then alternated half notes (480 ticks) and whole notes to create an offset rhythm. Beginning at measure 11, I mixed quarter notes (240 ticks), half notes and whole notes. The 480 tick offset makes interesting rhythmic juxtapositions when the 240, 240, 480 overlay the 480, 240, 240 on the other track.
Tips: if a note is not pleasing, you can use the arrow keys to transpose
it before entering any more notes. The corresponding note(s) in
the other track(s) will follow. You can also modify notes you
entered earlier by clicking and dragging them. (Make sure the
cursor has changed to a four-way arrow before doing this. This
cursor indicates that you are exactly over the note.) To maintain
consistency in the canon, only notes in voice 1 should be modified
in this way. (Note: To modify an individual note without changing the corresponding
note in the other voice, use the pen tool.)
The first section will end up on the fifth, B. The end of voice
2 was fixed manually to conclude both voices at the same time.
Step 4: Composing section B
The second section will employ faster melodic movement using 3
voices. The difficulty is increased when composing canons with
3 voices since the overlapping of delayed and transposed melodies
does not necessarily yield harmonious juxtapositions. Xx shows
all voices as they are entered. This allows you to see harmonic
relationships and tweak the canon accordingly.
Step 5: Fine Tuning