Mutable Instruments Marbles User manual

Marbles
Random sampler

About Marbles
Marbles is all about randomness – generation of random
events, or randomization of external CV/Gate signals. The
module is organized as three sections: the tsection gen-
erates and processes clocks and triggers, the Xsection
generates and processes voltages, and the DEJA VU section
imposes structure, in the form of repetition, upon all the
events generated by the two other sections.
Installation
Marbles requires a -12V/+12V power supply (2x5 pin con-
nector). The red stripe of the ribbon cable (-12V side) must
be oriented on the same side as the “Red stripe” marking on
the module and on your power distribution board.
The module draws 80mA from the +12V rail, and 20mA from
the -12V rail.
Online manual and help
The full manual can be found online at
mutable-instruments.net/modules/marbles/manual
For help and discussions, head to
mutable-instruments.net/forum
Please refer to the online manual for detailed infor-
mation regarding compliance with EMC directives

Marbles’ recipe for random music
1. Start with a clock – generated internally or divided/mul-
tiplied from an external clock signal.
2. If required, add some jitter to it, from slight humaniza-
tion to complete chaos.
3. Split this randomized clock into two streams of random
triggers to generate two contrasting rhythmic patterns
complementing the main clock.
4. Generate three random voltages in sync with the rhyth-
mic patterns obtained at the previous step.
5. Transform the random voltages to spread them further
apart, or concentrate them around a specific voltage.
6. Add a pinch of lag-processing to obtain smooth random
modulations... or quantization to get random tunes.
Steps 1 to 3 are handled by the left half of the module, the
random rhythms being generated on the outputs labelledt.
In your Eurorack system such duties might have been per-
formed by modules like Grids and Branches.
Steps 4 to 6 are handled by the right half of the module, the
random voltages being generated on the outputs labelledX.
A large number of modules would be necessary to patch
this functionality: a triple noise source and sample&hold,
waveshapers, quantizers, and lag processors.
And now let’s take it further: what if everything the module
did could be controlled by a slowly evolving or lockable loop,
like with Music Thing’s Turing Machine? That’s what the
DEJA VU section is for.
Time to dive into the details!

A
B
2
1
3
C
E
D

tGenerator
The t generator produces random gates by generating a
jittery master clock (which is output on t2) and deriving from
it two streams of random gates which are output on t1and t3.
A. Clock rate. 120 BPM at 12 o’clock.
B. Clock range. Divides or multiplies the clock rate by 4.
C. Amount of randomness in the clock timing - perfect-
ly stable, then simulating an instrumentalist lagging and
catching up, then... complete chaos.
D. Controls whether gates are more likely to occur on t1or
t3. Several methods are available for splitting the master
clock into t1and t3, selected by the button [E].
A coin is tossed at every pulse of t2, to decide whether
the pulse is passed to t1or t3. BIAS controls the fairness of
the coin toss.
t1and tare generated by respectively multiplying and
dividing t2by a random ratio. Turn the BIAS knob fully clock-
wise or counter-clockwise to reach more extreme ratios.
the triggers alternate between t1and t3, following the
same kind of regularity as kick/snare drum patterns.
1. BIAS, RATE (with V/O scaling) and JITTER CV inputs.
2. External clock input. The clock signal patched in this
input replaces the internal clock. In this case, the RATE knob
and CV input are re-purposed as a division/multiplication
control, and the jitter setting is applied to the external clock.
3. Gate outputs. Hold the button [E] and turn BIAS to adjust
the gate length from 1% to 99%, or JITTER to adjust the
gate length randomization (from deterministic to completely
random).

EF
4
G
H

DEJA VU section
Whenever the module needs to make a random choice (for
instance, to decide on the amount of jitter to apply on the
next tick of its clock, or to generate a random voltage for one
of its outputs), it queries the DEJA VU section. The DEJA VU
section either recyles a previously generated random choice,
or samples fresh random data from a hardware random
source.
E. F. These buttons control whether the DEJA VU settings
apply to the t or X section (or neither, or both). For exam-
ple, the module can generate a non-repeating sequence of
voltages locked to a looping rhythm (t enabled, X disabled);
or cycle through the same sequence of voltages on an ev-
er-changing rhythm (t disabled, X enabled).
G. Probability of re-cycling random decisions/voltages
from the past.
• From 7 o’clock to 12 o’clock, this probability goes from
0 (completely random) to 1 (locked loop).
• At 12 o’clock, the module is thus stuck in a loop,
because it never generates fresh random data. In this
case, the illuminated pushbuttons [E] and [F] blink.
• From 12 o’clock to 5 o’clock, the probability of randomly
jumping within the loop goes from 0 to 1.
• At 5 o’clock, the module thus plays random permuta-
tions of the same set of decisions/voltages.
H. Loop length.
4. DEJA VU CV input.

I
J
L
K
M

XGenerator
The X generator generates three independent random volt-
ages output on X1, X2and X3. They are clocked by the three
outputs from the t section, or by a common external clock.
I. Output voltage range. 0 to +2V, 0 to +5V or -5 to +5V.
J. Probability distribution width and shape. Turning count-
er-clockwise from 12 o’clock, the voltages are increasingly
concentrated near the center of the range. Fully count-
er-clockwise, a constant voltage is output. At 12 o’clock,
they follow a bell curve - more likely to occur near the cen-
ter but able to reach the extremes. At 2 o’clock, they occupy
the entire voltage range with equal probability. Past this
point, extreme values become more likely. Fully clockwise,
only the minimum and maximum voltages are possible,
turning X1, X2and X3into random gates.
K. Distribution bias. Skews the distribution towards low or
high voltages. Think of this as the probabilistic equivalent of
an offset: it does not shift the voltage down or up, but biases
the decision towards the bottom or top of the voltage range.
L. Horizontal and vertical “steppiness” of the generated
voltages. At 12 o’clock, generates the typical S&H steps.
Turn CCW to generate smoother edges, then random linear
segments, then smooth random curves. Turn CW to quantize
the generated voltages to a scale, then to progressively strip
the scale of its notes until only the root note remains.
M. Controls how the outputs X1, X2and X3react to the
settings dialed on the knobs [J], [K] and [L] – allowing you
to obtain different flavors of random voltages from the 3
outputs (>continues on next page).

N
6
5
7
M

All channels follow the settings on the control panel.
X2follows the control panel, while X1and X3take opposite
values. For example, if STEPS is turned fully CW, X1and X3
will be smooth while X2is quantized to the root note and its
octaves.
X1follows the control panel, X3reacts in the opposite di-
rection, and X2always stays in the middle (steppy, unbiased,
bell-curve).
N. External processing mode (>see the next section).
5. STEPS, SPREAD and BIAS CV inputs.
6. External clock input. When patched, all three outputs
follow the same external clock, as opposed to being clocked
by the three outputs from the tsection.
7. CV outputs.
Sampling external CVs with the X generator
Press the button [N] to enable the external processing
mode. In this mode, the module samples the voltage present
on the SPREAD CV input (5) whenever a random value is
needed for one of the X outputs. This allows the artist to
sample, loop, quantize, shuffle, or transpose external CVs.
YGenerator
The Y generator, by default, is a smooth, full-range (-5V to
+5V), random source that is clocked at 1/16 the rate of X2.
These settings can be modified by holding the button [M]
and adjusting RATE (division factor relative to X2, from 1/64
to 1), SPREAD, BIAS and STEPS while the button is held. The
Youtput is never affected by the DEJA VU section.

Shaping voltage distributions with
SPREAD and BIAS
BIAS
SPREAD

BIAS
SPREAD
BIAS
SPREAD
The pink histogram represents the distribution of possible
output voltages: the tallest bar corresponds to the most
likely outcome. The teal oscillogram is an example of
output voltage sequence.

Selecting a scale
Hold the voltage range button [I] for 2 seconds and re-
peatedly press it to select a scale. The color of the blinking
LED and the rate of blinking indicates the active scale. Six
memory slots are available for recording scales. They are
pre-programmed with scales rooted in C.
STEPS Quantizer
The STEPS knob progressively eliminates notes from a chro-
matic scale: first to reveal an interesting scale, then to mask
all notes except the most salient ones in this scale. The
example below is for a C-major scale (first factory preset).
STEPS
Chromatic scale
Unquantized

Programming a scale
1. Connect the CV and Gate outputs of a keyboard or
MIDI interface to the SPREAD (5) and CLOCK (6) inputs
respectively.
2. Hold the external processing mode button [N] for 2
seconds. The LED above the scale selection button [I]
blinks and indicates the active scale.
3. Play a little jam in the scale you want to program. Fifty
notes, or more, is the recommended length.
4. Press the button [N] when done.
The module analyzes your jam to measure how frequently
each note occurs. The least frequently played notes will be
the first to be eliminated when STEPS is turned clockwise
from 12 o’clock. The most frequently played note will be the
last one to remain when STEPS is at 5 o’clock.
Note: it is also possible, at step 3, to play the scale in
ascending order, instead of a long melody. In this case, the
module will not know the relative importance of each note
of the scale, and the gradual scale “carving” will not be per-
formed: turning the STEPS button from 12 o’clock to 5’clock
will not modify the scale.
Preset scales
Major
Minor
Pentatonic
Gamelan (Pelog)
Raag Bhairav
Raag Shree
Slow blink Fast blink

Tips and tricks
• If DEJA VU is past 12 o’clock and the loop length
is set to 1, the outputs remain frozen in the same
state.
• If DEJA VU is around 11 o’clock, the loop will
slowly mutate.
• The DEJA VU knob has a “virtual notch” at 12
o’clock - even if it is not exactly at 12 o’clock, you
will still get a perfectly non-random loop.
• Once a sequence is looping, it is still possible to
alter it with SPREAD/BIAS to map it to a differ-
ent range of voltages.
• Once a sequence is looping, a rapid double press
on the DEJA VU buttons reseeds it.
• When the X section is not externally clocked,
X1, X2and X3are rhythmically independent from
each other, each output changing its voltage at
its own pace. Setting the loop LENGTH to 3 (for
example), will cause each output to go through a
3-note sequence independently from the other,
creating polyrythmic effects.
• Self-patching is a rewarding technique with
Marbles! In particular, the Youtput provides a
useful slow modulation source for randomizing
the other parameters of the module.