Rev. 5 – Jun 2020 Page 32 of 91
Patch it to the 1V/oct input of your oscillator and then
push the Play button (B.13) to hear the sequence.
Now you may need gate signals in order to separate the
notes and add dynamics to your sequence. Push the Gate
A button (B.9) to access the Gate Channel and rotate the
Stage Encoder (A.1) as before.
You are now defining the individual gate-high time for
each of the 16 notes you entered. Patch the Gate A output
of Track 1 (E.3) e.g. to an envelope controlling the VCA,
or the filter.
What you just obtained is a sequence of 16 notes with
equal duration. Feel like something is missing? It actually
is. In order to learn how to work with full polyphony,
have faster or slower sequences at the same time, change
the length of the notes, make a single note vary every time
it is played, but still in the key you chose, have some ran-
dom ratcheting on a given stage, loop a section within a
song structure, and many other things, please take a deep
breath and keep reading.
2 PHILOSOPHY AND DESIGN
USTA is a 4×4 tracks, variable-stage-length sequencer
for voltages and gates.
Variable stage length means that every single stage dura-
tion can be individually set in relation to the clock, instead
of being constrained to a one-to-one ratio (i.e. one step
per every clock impulse).
4×4 tracks means that every stage can store and generate
up to four separate voltages (two CV and two gates) and
that up to four independent sequences can be arranged
as simultaneous tracks.
USTA’s user interface is based on a straightforward 16-
stage circular design with an array of multi-functional en-
coders with push switch and buttons. This allows users to
easily navigate within the sequencer’s flexible software
architecture and to quickly display and edit relationships
between the different stages.
Those main features are what makes USTA the Euro-
rack Voltage Score: its flexibility on the time, rhythm and
harmony domain, its large set of independent outputs
and its performance-oriented interface allow the user to
achieve nearly any musical result, from fine Baroque po-
lyphony to the most extreme polyrhythmic noise live per-
formance.
ARCHITECTURE
USTA’s architecture is designed to provide a wide set
of compositional tools without sacrificing the user-friend-
liness.
The smallest “brick” of the sequencer is the stage, which
contains two separate control voltage values, two separate
gate values and all the behavioral information
necessaryto generate four synchronous musical events,
including pitch, volume, timbre, repetition, probability…
A sequence of up to 16 stages (one per encoder) forms
a pattern, in the same way that a series of individual musi-
cal events forms a melody.
Up to 32 patterns are contained in a track, which can be
compared to a musical piece for solo instrument. Beside
all the melodic content stored in a pattern, a track con-
tains also the performance information, including: which
pattern is currently playing, which external control is
used as modulator, and so on. Four tracks are simultane-
ously available in USTA, and they can have different
tempos, number of stages and patterns.
Just like any musical piece, the track can be either im-
provised, when the musician decides all these perfor-
mance details on the go, or carefully composed first, and
then played back: in order to accomplish this last task,
USTA allows an alternative playing mode called song, in
which all the patterns can be arranged in a pre-deter-
mined set.
This information can be independently set per each of
USTA’s four tracks. All the four tracks along with their
data and information are contained in a project, which is
the general operational framework of the sequencer. A
project can be stored on the included micro SD and re-
called whenever is needed (one project at a time). On the
first startup an empty project is created (called NONAME),
then at every other startup USTA automatically will re-
call the last project opened how it was saved. Projects and
trimming settings can be backed up on your computer
from the micro SD.
TEMPO MANAGEMENT
Conventional step sequencers use the reference clock to
jump from one step to the other. This means that the step
duration, which is the time from one step to the other,
corresponds to the period between consecutive clock im-
pulses.
USTA, on the other hand, allows every stage to have a
different length that can be set in relation to the reference
clock (and this is one reason why the term stage is pre-
ferred over step).
Such relation is achieved through two deeply connected
concepts, time units and time ratio. The unit is the shortest
possible duration of a given stage, while the ratio defines
the unit length in respect of the clock tempo.
It is possible to have 16 different time ratios: 8 are clock
divisions, thus providing units that are longer than the
clock impulses; 7 are clock multiplications, thus providing
units that are shorter than the clock impulses; one is the
exact clock period, thus providing units that are as long
as the clock impulses.
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