1/19/2018
Mutable Instruments | Yarns
https://mutable-instruments.net/modules/yarns/manual/
6/10
TUNING SYSTEMS
Yarns uses highly accurate 16-bit DACs for CV conversion, and is capable of very precise control over tuning.
TT (TRANSPOSE) applies a coarse transposition to the input note, expressed in semitones. Note that this is
equivalent to a keyboard transposition, rather than an offset on the output voltage - this might not matter
much when using equal temperament, but matters when other tuning systems are used.
TF (FINE TUNING) applies a fine transposition to the output CV, expressed in 1/128th of a semitone (0.65mV
increments).
TS (TUNING SYSTEM) selects alternative scales and tuning systems. EQ(UAL TEMPERAMENT) is the
default choice. JU(ST INTONATION) uses a simple algorithm to adjust each note by a few cents within its
equal temperament value to increase consonance with the notes played on the other channels, or the most
recently played notes. PY(THAGOREAN) uses a pythagorean scale, in which all notes’ frequency ratios are
expressed as rational numbers (as opposed to powers of 2\^-
1
⁄
2
for equal temperament). EB, E, and EA have
these respective notes shifted down by one quartertone. The settings numbered from 01 to 27 are ragas from
the
Maihar Gharana
- these settings not only affect tuning but also eliminate some notes from the scale to
leave only the shrutis belonging to the raga. The last setting, CU(STOM) uses an octave pitch table which
can be sent by SysEx using the
MIDI Tuning Scale/Octave Extensions (CA-021/RP-020)
of the MIDI
standard. This
web app
can be used to create tunings using the very popular Scala scale description
language.
TR (TUNING ROOT) acts in the same way as a transposition control, but instead of shifting notes up/down, it
rotates up or down the tuning table (whether it is one of the preset tables or the one received by MIDI). For
example, if a tuning table with a quarter-tone E has been programmed, setting TR (TUNING ROOT) to C# will
rotate the tuning table one semitone up, and the quarter-tone will be on the note F instead. This setting has
no effect in equal temperament tuning. For the ragas settings, this is equivalent to moving the “Sa” up or
down on the keyboard.
CLOCK AND TEMPO
Before diving into the sequencer and arpeggiator, a presentation of Yarns’ clocking system… All the timing
information for the sequencers, arpeggiators, and euclidean pattern generators derive from the same clock -
though each part can be tuned to its own subdivision of this clock.
Yarns can use either its own internal clock, or an external MIDI clock source. The tempo is adjusted by
modifying the TE(MPO) setting. Below 40 BPM, the display shows EX(TERNAL) - which means that the
internal clock will not be used and that external MIDI clock messages are expected. Note that the display only
shows the last 2 digits of the tempo; but rhythmically blinks - so there’s no confusion between 60 and 160, or
120 and 220! The tempo can also be set by tapping on the tap tempo button on the front panel.
Some swing might be applied to the internal clock - its amount is controlled by the SW(ING) setting.
A divider is applied to this tempo. Its ratio can be controlled by the I/ (INPUT CLK DIV) setting. This can be
used to create drastic tempo changes in a sequence.
With single and dual voice layouts (1M, 2M, 2P, 2>, 4>), or with the quad-trigger layout (4T), a clock and
bar/reset output is available on gate outputs 3 and 4. The clock output emits a pulse signal at a division of the
main clock. The rhythmic subdivision is selected by the O/ (OUTPUT CLK DIV) setting - the default value
being 16 (1/16th note). The start/bar trigger output emits a trigger whenever the sequencer is started, but
can also be configured to re-emit a trigger every Nth quarter note. This value is defined by the B- (BAR
DURATION) setting. Set it to oo and a pulse will only be emitted when the sequence start. Set it to, for
example, 4, and a pulse will be emitted at the beginning of each 4-beats bar. Set it to 0 and the output will
stay high while the sequence is running.
In the quad voice layouts (4M, 4P, 8>), gate outputs 3 and 4 are reserved for controlling the gate of
voice/channel 3 and voice/channel 4. However, these outputs can be replaced by clock and bar/reset outputs,
