Mutable Instruments Marbles User Manual

Mutable Instruments | Marbles

Marbles requires a -12V/+12V power supply (2x5 pin connector). 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.

This device complies with part 15 of the FCC Rules. Operation is subject to the following
two conditions: (1) This device may not cause harmful interference, and (2) this device must
accept any interference received, including interference that may cause undesired
operation.

This device meets the requirements of the following standards: EN55032, EN55103-2,
EN61000-3-2, EN61000-3-3, EN62311.

Start with a clock – generated internally or divided/multiplied from an external clock signal.1.
If required, add some jitter to it, from slight humanization to complete chaos.2.
Split this randomized clock into two streams of random triggers to generate two contrasting rhythmic

3.

patterns complementing the main clock.

Generate three random voltages in sync with the rhythmic patterns obtained at the previous step.4.
Transform the random voltages to spread them further apart, or concentrate them around a specific

5.
voltage.

Add a pinch of lag-processing to obtain smooth random modulations… or quantization to get random tunes.6.

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 performed 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!

1 of 8

Mutable Instruments | Marbles

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 t1 and 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 - perfectly stable, then simulating an instrumentalist

lagging and catching up, then… complete chaos.

D. Bias. Controls whether gates are more likely to occur on t1 or t3. Several methods are available for

splitting the master clock into t1 and t3, selected by the button [E]:

A coin is tossed at every pulse of t2, to decide whether the pulse is passed to t1 or t3. BIAS controls the

1.
fairness of the coin toss.

t1 and t3 are generated by respectively multiplying and dividing t2 by a random ratio. Turn the BIAS knob fully

2.
clockwise or counter-clockwise to reach more extreme ratios.
the triggers alternate between t1 and t3, following the same kind of regularity as kick/snare drum patterns.3.

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).

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.

F. G. These buttons control whether the DEJA VU settings apply to the t or X section (or neither, or both).

For example, 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 ever-changing rhythm (t
disabled, X enabled).

H. Probability of re-cycling random decisions/voltages from the past:

2 of 8

Mutable Instruments | Marbles

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 [F] and [G] 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 permutations of the same set of decisions/voltages.

I. Loop length. Lengths of 5, 7, 10 and 14 can be obtained by setting the knob between the graduations

printed on the panel.

4. DEJA VU CV input.

The X generator generates three independent random voltages output on X1, X2 and X3. They are
clocked by the three outputs from the t section, or by a common external clock.

J. Output voltage range. 0 to +2V, 0 to +5V or -5 to +5V.

K. Probability distribution width and shape. Turning counter-clockwise from 12 o’clock, the voltages are

increasingly concentrated near the center of the range. Fully counter-clockwise, a constant voltage is
output. At 12 o’clock, they follow a bell curve - more likely to occur near the center 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, X2 and X3 into random gates.

L. 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.

In the illustration below, 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.

M. 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.

3 of 8